diff --git a/langserver/java/import-resolver.js b/langserver/java/import-resolver.js
new file mode 100644
index 0000000..7974ec2
--- /dev/null
+++ b/langserver/java/import-resolver.js
@@ -0,0 +1,116 @@
+/**
+ * @typedef {import('./parsetypes/import')} ImportDeclaration
+ */
+const ResolvedImport = require('./parsetypes/resolved-import');
+
+/**
+ * Search a space-separated list of type names for values that match a dotted import.
+ * 
+ * @param {string} typenames newline-separated list of fully qualified type names
+ * @param {string} dotted_import fully-qualified import name (e.g "java.util")
+ * @param {boolean} demandload true if this is a demand-load import
+ */
+function fetchImportedTypes(typenames, dotted_import, demandload) {
+    const matcher = demandload
+        // for demand-load, we search for any types that begin with the specified import name
+        // - note that after the import text, only words and $ are allowed (because additional dots would imply a subpackage)
+        ? new RegExp(`^${dotted_import.replace(/\./g, '[.$]')}[.$][\\w$]+$`, 'gm')
+        // for exact-load, we search for any types that precisely matches the specified import name
+        : new RegExp(`^${dotted_import.replace(/\./g, '[.$]')}$`, 'gm');
+
+    // run the regex against the list of type names
+    const matching_names = typenames.match(matcher);
+    return matching_names;
+}
+
+/**
+ * @param {string} typenames newline-separated list of fully qualified type names
+ * @param {import('./parsetypes/import')} import_decl import declaration
+ */
+function resolveImportTypes(typenames, import_decl) {
+    const dotted = import_decl.getDottedName();
+    return fetchImportedTypes(typenames, dotted, !!import_decl.asterisk);
+}
+
+/**
+ * Resolve a set of imports for a module.
+ * 
+ * Note that the order of the resolved imports is important for correct type resolution:
+ *   - same-package imports are first,
+ *   - followed by import declarations (in order of declaration),
+ *   - followed by implicit packages
+ * 
+ * @param {*} androidLibrary imported types from the Android platform library
+ * @param {import('./parsetypes/import')[]} imports list of declared imports in the module
+ * @param {string} package_name package name of the module
+ * @param {import('./mti').Type[]} source_mtis MTIs representing types declared in the source
+ * @param {string[]} [implicitPackages] list of implicit demand-load packages
+ */
+function resolveImports(androidLibrary, imports, package_name, source_mtis, implicitPackages = ['java.lang']) {
+    /**
+     * create a new Map that maps JRE type names to MTI instances
+     * @type {Map<string, import('./mti').Type>}
+     */
+    const typemap = new Map(
+        androidLibrary.types.map(mti => [`${mti.package}.${mti.name}`, mti])
+    );
+    // add the source MTIs
+    // todo - should we overwrite entries when source MTIs match types in the library?
+    source_mtis.forEach(mti => typemap.set(`${mti.package}.${mti.name}`, mti))
+
+    // construct the list of typenames
+    const typenames = [...typemap.keys()].join('\n');
+
+    /**
+     * The list of explicit import declarations we are unable to resolve
+     * @type {ImportDeclaration[]}
+     */
+    const unresolved = [];
+
+    /** @type {ResolvedImport[]} */
+    const resolved = [];
+
+    // import types matching the current package
+    if (package_name) {
+        const matches = fetchImportedTypes(typenames, package_name, true);
+        if (matches)
+            resolved.push(new ResolvedImport(null, matches, typemap, 'owner-package'));
+    }
+
+    // import types from each import declaration
+    imports.forEach(import_decl => {
+        const matches = resolveImportTypes(typenames, import_decl);
+        if (matches) {
+            resolved.push(new ResolvedImport(import_decl, matches, typemap, 'import'));
+        } else {
+            // if we cannot match the import to any types, add it to the unresolved list so
+            // we can flag it as a warning later.
+            // Note that empty packages (packages with no types) will appear here - they
+            // are technically valid, but represent useless imports
+            unresolved.push(import_decl);
+        }
+    });
+
+    // import types from the implicit packages
+    implicitPackages.forEach(package_name => {
+        const matches = fetchImportedTypes(typenames, package_name, true);
+        if (matches)
+            resolved.push(new ResolvedImport(null, matches, typemap, 'implicit-import'));
+    })
+
+    /**
+     * return the resolved and unresolved imports.
+     * The typemap is also included to support fully qualified type names that, by virtue of 
+     * being fully-qualified, don't require importing.
+     */
+    return {
+        resolved,
+        unresolved,
+        typemap,
+    }
+}
+
+module.exports = {
+    resolveImports,
+    ResolvedImport,
+}
diff --git a/langserver/java/mti.js b/langserver/java/mti.js
index 1869763..a749d0c 100644
--- a/langserver/java/mti.js
+++ b/langserver/java/mti.js
@@ -16,22 +16,27 @@ function packageNameFromRef(ref, mti) {
 
 /**
  * @param {number} ref 
- * @param {MTI} mti
+ * @param {MTI} unit
  */
-function typeFromRef(ref, mti) {
+function typeFromRef(ref, unit) {
     if (typeof ref !== 'number') {
         return null;
     }
     if (ref < 16) {
         return KnownTypes[ref];
     }
-    return mti.referenced.types[ref - 16];
+    return unit.referenced.types[ref - 16];
 }
 
 function indent(s) {
     return '\n' + s.split('\n').map(s => `    ${s}`).join('\n');
 }
 
+/**
+ * @typedef {MTIType|MTIArrayType|MTIPrimitiveType} Type
+ * @typedef {'class'|'interface'|'enum'|'@interface'|'primitive'|'array'} MTITypeKind
+ */
+
 class MinifiableInfo {
 
     constructor(minified) {
@@ -75,11 +80,132 @@ class MinifiableInfo {
     ```
  */
 class MTI extends MinifiableInfo {
+    /**
+     * @param {string} package_name
+     * @param {string} docs
+     * @param {string[]} modifiers 
+     * @param {'class'|'enum'|'interface'|'@interface'} typeKind 
+     * @param {string} name 
+     */
+  addType(package_name, docs, modifiers, typeKind, name) {
+      const t = {
+          d: docs,
+          p: this.addPackage(package_name),
+          m: getTypeMods(modifiers, typeKind),
+          n: name.replace(/\./g,'$'),
+          v: [],
+          e: /interface/.test(typeKind) ? [] 
+            : typeKind === 'enum' ? this.addRefType('java.lang', 'Enum')
+            : this.addRefType('java.lang', 'Object'),
+          i: [],
+          f: [],
+          c: [],
+          g: [],
+      }
+      this.minified.it.push(t);
+      const mtitype = new MTIType(this, t);
+      this.types.push(mtitype);
+      return mtitype;
+  }
+
+  /**
+   * @param {number} base_typeref 
+   * @param {number[]} type_args 
+   */
+    addGenericRefType(base_typeref, type_args) {
+        const targs_key = type_args.join(',');
+        let idx = this.minified.rt.findIndex(t => (t.n === base_typeref) && !t.a && t.g && (t.g.join(',') === targs_key));
+        if (idx < 0) {
+            const rt_mti = {
+                n: base_typeref,
+                g: type_args,
+            };
+            idx = this.minified.rt.push(rt_mti) - 1;
+            this.referenced.types.push(new ReferencedType(this, rt_mti));
+        }
+        return idx + 16;
+    }
+
+    addArrayRefType(element_typeref, dimensions) {
+        let idx = this.minified.rt.findIndex(t => (t.n === element_typeref) && !t.g && (t.a === dimensions));
+        if (idx < 0) {
+            const rt_mti = {
+                n: element_typeref,
+                a: dimensions,
+            };
+            idx = this.minified.rt.push(rt_mti) - 1;
+            this.referenced.types.push(new ReferencedType(this, rt_mti));
+        }
+        return idx + 16;
+    }
 
     /**
-     * @param {{rp:[], rt:[], it:[]}} mti 
+     * @param {string} package_name 
+     * @param {string} type_name 
      */
-    constructor(mti) {
+    addRefType(package_name, type_name) {
+        let idx;
+        if (!package_name || package_name === 'java.lang') {
+            idx = KnownTypes.findIndex(t => t.name === type_name);
+            if (idx >= 0) {
+                return idx;
+            }
+        }
+        const pkgref = this.addPackage(package_name);
+        const jre_type_name = type_name.replace(/\./g, '$');
+        idx = this.minified.rt.findIndex(t => t.p === pkgref && t.n === jre_type_name);
+        if (idx < 0) {
+            const rt_mti = {
+                p: pkgref,
+                n: jre_type_name,
+            };
+            idx = this.minified.rt.push(rt_mti) - 1;
+            this.referenced.types.push(new ReferencedType(this, rt_mti))
+        }
+        return idx + 16;
+    }
+
+    /**
+     * @param {string} packagename 
+     */
+    addPackage(packagename) {
+        let idx = KnownPackages.indexOf(packagename);
+        if (idx >= 0) {
+            return idx;
+        }
+        idx = this.minified.rp.indexOf(packagename);
+        if (idx < 0) {
+            idx = this.minified.rp.push(packagename) - 1;
+        }
+        return idx + 16;
+    }
+
+    static get defaultPackageRef() {
+        return KnownPackages.indexOf("");
+    }
+
+    /**
+     * @param {string} name 
+     */
+    static fromPrimitive(name) {
+        return MTIPrimitiveType.fromName(name);
+    }
+
+    /**
+     * @param {Type} element 
+     */
+    static makeArrayType(element, dimensions) {
+        let res = element;
+        for (let i = 0; i < dimensions; i++) {
+            res = new MTIArrayType(res);
+        }
+        return res;
+    }
+
+    /**
+     * @param {{rp:string[], rt:*[], it:*[]}} mti 
+     */
+    constructor(mti = {rp:[],rt:[],it:[]}) {
         super(mti);
         // initialise the lists of referenced packages and types
         this.referenced = {
@@ -162,7 +288,7 @@ class ReferencedType extends MinifiableInfo {
             baseType,
 
             /** @type {ReferencedType[]} */
-            typeParams: mti.g && mti.g.map(t => typeFromRef(t, unit)),
+            typeArgs: mti.g && mti.g.map(t => typeFromRef(t, unit)),
 
             /** @type {string} */
             arr: '[]'.repeat(mti.a | 0),
@@ -177,10 +303,10 @@ class ReferencedType extends MinifiableInfo {
     get name() {
         // note: names in enclosed types are in x$y format
         const n = this.parsed.baseType ? this.parsed.baseType.name : this.minified.n;
-        const type_params = this.parsed.typeParams
-            ? `<${this.parsed.typeParams.map(tp => tp.name).join(',')}>`
+        const type_args = this.parsed.typeArgs
+            ? `<${this.parsed.typeArgs.map(tp => tp.name).join(',')}>`
             : ''
-        return `${n}${type_params}${this.parsed.arr}`;
+        return `${n}${type_args}${this.parsed.arr}`;
     }
 
     get dottedName() {
@@ -188,6 +314,97 @@ class ReferencedType extends MinifiableInfo {
     }
 }
 
+class MTITypeBase extends MinifiableInfo {
+    /**
+     * type docs
+     * @type {string}
+     */
+    get docs() { return this.minified.d }
+    
+    /**
+     * type modifiers
+     * @type {number}
+     */
+    get modifiers() { return this.minified.m }
+
+    /**
+     * type name (in x$y format for enclosed types)
+     * @type {string}
+     */
+    get name() { return this.minified.n }
+
+    /**
+     * package this type belongs to
+     */
+    get package() { return null }
+
+    /**
+     * @type {MTIConstructor[]}
+     */
+    get constructors() { return [] }
+
+    /**
+     * @type {MTIField[]}
+     */
+    get fields() { return [] }
+
+    /**
+     * @type {MTIMethod[]}
+     */
+    get methods() { return [] }
+
+    /**
+     * @param {string} name 
+     */
+    hasModifier(name) {
+        return ((this.minified.m | 0) & getModifierBit(name)) !== 0;
+    }
+
+    toSource() {
+        return this.name;
+    }
+}
+
+class MTIArrayType extends MTITypeBase {
+    /**
+     * @param {Type} element_type 
+     */
+    constructor(element_type) {
+        super({
+            n: element_type.name + '[]',
+            d: '',
+            m: 0,   // should array types be implicitly final?
+        });
+        this.element_type = element_type;
+    }
+
+    get fullyDottedRawName() { return `${this.element_type.fullyDottedRawName}[]` }
+
+    /** @type {MTITypeKind} */
+    get typeKind() { return 'array' }
+}
+
+class MTIPrimitiveType extends MTITypeBase {
+
+    static _cached = new Map();
+    static fromName(name) {
+        let value = MTIPrimitiveType._cached.get(name);
+        if (!value) {
+            value = new MTIPrimitiveType({
+                n: name,
+                d: '',
+                m: 0,
+            });
+            MTIPrimitiveType._cached.set(name, value);
+        }
+        return value;
+    }
+    
+    get fullyDottedRawName() { return this.name }
+
+    /** @type {MTITypeKind} */
+    get typeKind() { return 'primitive' }
+}
 
 /**
  * MTIType encodes a complete type (class, interface or enum)
@@ -205,7 +422,7 @@ class ReferencedType extends MinifiableInfo {
  * }
  * ```
  */
-class MTIType extends MinifiableInfo {
+class MTIType extends MTITypeBase {
 
     /**
      * @param {MTI} unit 
@@ -241,26 +458,13 @@ class MTIType extends MinifiableInfo {
         }
     }
 
-    /**
-     * type docs
-     * @type {string}
-     */
-    get docs() { return this.minified.d }
-
-    /**
-     * type modifiers
-     * @type {number}
-     */
-    get modifiers() { return this.minified.m }
-    
-    /**
-     * type name (in x$y format for enclosed types)
-     * @type {string}
-     */
-    get name() { return this.minified.n }
-
     get dottedRawName() { return this.minified.n.replace(/[$]/g, '.') };
 
+    get fullyDottedRawName() {
+        const pkg = this.package;
+        return pkg ? `${pkg}.${this.dottedRawName}` : this.dottedRawName;
+    };
+
     get dottedName() {
         const t = this.typevars.map(t => t.name).join(',');
         return t ? `${this.dottedRawName}<${t}>` : this.dottedRawName;
@@ -277,6 +481,7 @@ class MTIType extends MinifiableInfo {
      */
     get package() { return this.parsed.package }
 
+    /** @type {MTITypeKind} */
     get typeKind() {
         const m = this.minified.m;
         return (m & TypeModifiers.enum)
@@ -332,7 +537,9 @@ class MTIType extends MinifiableInfo {
             // only add extends if it's not derived from java.lang.Object
             if (this.extends !== KnownTypes[3]) {
                 const x = Array.isArray(this.extends) ? this.extends : [this.extends];
-                ex = `extends ${x.map(type => type.dottedName).join(', ')} `;
+                if (x.length) {
+                    ex = `extends ${x.map(type => type.dottedName).join(', ')} `;
+                }
             }
         }
 
@@ -348,6 +555,85 @@ class MTIType extends MinifiableInfo {
             `}`
         ].join('\n');
     }
+
+    /**
+     * @param {MTI} unit
+     * @param {number} typeref 
+     */
+    setExtends(unit, typeref) {
+        if (Array.isArray(this.minified.e)) {
+            this.minified.e.push(typeref);
+            // @ts-ignore
+            this.parsed.extends.push(typeFromRef(typeref, unit));
+        } else {
+            this.minified.e = typeref;
+            this.parsed.extends = typeFromRef(typeref, unit);
+        }
+    }
+
+    /**
+     * @param {MTI} unit 
+     * @param {string} docs 
+     * @param {string[]} modifiers 
+     * @param {number} typeref 
+     * @param {string} name 
+     */
+    addField(unit, docs, modifiers, typeref, name) {
+        const o = {
+            d: docs,
+            m: getAccessMods(modifiers),
+            n: name,
+            t: typeref,
+        }
+        this.minified.f.push(o);
+        this.parsed.fields.push(new MTIField(unit, o));
+    }
+
+    /**
+     * @param {MTI} unit 
+     * @param {string} docs 
+     * @param {string[]} modifiers 
+     */
+    addConstructor(unit, docs, modifiers) {
+        const o = {
+            d: docs,
+            m: getAccessMods(modifiers),
+            p: [],
+        }
+        this.minified.c.push(o);
+        const c = new MTIConstructor(unit, o);
+        this.parsed.constructors.push(c);
+        return c;
+    }
+
+    /**
+     * @param {MTI} unit 
+     * @param {MTIType} owner 
+     * @param {string} docs 
+     * @param {string[]} modifiers 
+     * @param {number} typeref 
+     * @param {string} name 
+     */
+    addMethod(unit, owner, docs, modifiers, typeref, name) {
+        let g = this.minified.g.find(m => m.name === name);
+        if (!g) {
+            g = {
+                n:name,
+                s: [],
+            }
+            this.minified.g.push(g);
+        }
+        const o = {
+            d: docs,
+            m: getAccessMods(modifiers),
+            t: typeref,
+            p: [],
+        };
+        g.s.push(o);
+        const method = new MTIMethod(unit, owner, name, o);
+        this.parsed.methods.push(method);
+        return method;
+    }
 }
 
 /**
@@ -442,6 +728,22 @@ class MTIConstructor extends MTIMethodBase {
         const typename = this.parsed.typename.split('$').pop();
         return `${this.fmtdocs()}${access(this.modifiers)}${typename}(${this.parameters.map(p => p.toSource()).join(', ')}) {}`
     }
+
+    /**
+     * @param {MTI} unit 
+     * @param {string[]} modifiers 
+     * @param {number} typeref 
+     * @param {string} name 
+     */
+    addParameter(unit, modifiers, typeref, name) {
+        const o = {
+            m: getAccessMods(modifiers),
+            t: typeref,
+            n: name,
+        }
+        this.minified.p.push(o);
+        this.parsed.parameters.push(new MTIParameter(unit, o));
+    }
 }
 
 /**
@@ -518,6 +820,10 @@ class MTIConstructor extends MTIMethodBase {
      */
     get parameters() { return this.parsed.parameters }
 
+    toDeclSource() {
+        return `${this.return_type.dottedName} ${this.name}(${this.parameters.map(p => p.toSource()).join(', ')})`;
+    }    
+
     toSource() {
         let m = this.modifiers, body = ' {}';
         if (m & 0x400) {
@@ -530,6 +836,22 @@ class MTIConstructor extends MTIMethodBase {
         }
         return `${this.fmtdocs()}${access(m)}${this.return_type.dottedName} ${this.name}(${this.parameters.map(p => p.toSource()).join(', ')})${body}`
     }
+
+    /**
+     * @param {MTI} unit 
+     * @param {string[]} modifiers 
+     * @param {number} typeref 
+     * @param {string} name 
+     */
+    addParameter(unit, modifiers, typeref, name) {
+        const o = {
+            m: getAccessMods(modifiers),
+            t: typeref,
+            n: name,
+        }
+        this.minified.p.push(o);
+        this.parsed.parameters.push(new MTIParameter(unit, o));
+    }
 }
 
 /**
@@ -589,6 +911,27 @@ function access(modifier_bits) {
     return decls.join(' ');
 }
 
+/**
+ * @param {string} modifier 
+ */
+function getModifierBit(modifier) {
+    const i = access_keywords.indexOf(modifier);
+    return i < 0 ? 0 : (1 << i);
+}
+
+/**
+ * @param {string[]} modifiers 
+ * @param {boolean} [varargs] 
+ */
+function getAccessMods(modifiers, varargs = false) {
+    let m = 0;
+    modifiers.forEach(modifier => m |= getModifierBit(modifier));
+    if (varargs) {
+        m |= getModifierBit('transient');
+    }
+    return m;
+}
+
 const TypeModifiers = {
     public:       0b0000_0000_0000_0001,    // 0x1
     final:        0b0000_0000_0001_0000,    // 0x10
@@ -620,6 +963,29 @@ function typemods(modifier_bits) {
     return modifiers.join(' ');
 }
 
+/**
+ * @param {string[]} modifiers 
+ * @param {MTITypeKind} typeKind 
+ */
+function getTypeMods(modifiers, typeKind) {
+    let m = 0;
+    if (modifiers.includes('public')) m |= TypeModifiers.public;
+    if (modifiers.includes('final')) m |= TypeModifiers.final;
+    if (modifiers.includes('abstract')) m |= TypeModifiers.abstract;
+    switch (typeKind) {
+        case "interface": 
+            m |= TypeModifiers.interface | TypeModifiers.abstract;
+            break;
+        case "@interface": 
+            m |= TypeModifiers['@interface'] | TypeModifiers.abstract;
+            break;
+        case "enum": 
+            m |= TypeModifiers.enum | TypeModifiers.final;
+            break;
+    }
+    return m;
+}
+
 /**
  * List of known/common packages.
  * These are used/encoded as pkgrefs between 0 and 15.
diff --git a/langserver/java/parser.js b/langserver/java/parser.js
new file mode 100644
index 0000000..3eae70d
--- /dev/null
+++ b/langserver/java/parser.js
@@ -0,0 +1,498 @@
+const Annotation = require('./parsetypes/annotation');
+const Declaration = require('./parsetypes/declaration');
+const FMCDeclaration = require('./parsetypes/fmc');
+const ImportDeclaration = require('./parsetypes/import');
+const PackageDeclaration = require('./parsetypes/package');
+const ParameterDeclaration = require('./parsetypes/parameter');
+const ParseProblem = require('./parsetypes/parse-problem');
+const ParseResult = require('./parsetypes/parse-result');
+const ParseSyntaxError = require('./parsetypes/parse-error');
+const ProblemSeverity = require('./parsetypes/problem-severity');
+const Token = require('./parsetypes/token');
+const TypeDeclaration = require('./parsetypes/type');
+const TypeIdent = require('./parsetypes/typeident');
+const TypeParameters = require('./parsetypes/type-parameters');
+/**
+ * @typedef {import('./parsetypes/modifier')} Modifier
+ */
+
+
+ /**
+  * @param {Token[]} tokens 
+  * @param {number} idx 
+  */
+function findToken(tokens, idx) {
+    return tokens.find(t => t.simplified_text_idx === idx);
+}
+
+/**
+ * @param {string} simplified 
+ * @param {number} lastIndex 
+ */
+function parseToBracketEnd(simplified, lastIndex) {
+    // parse until close bracket
+    let re = /[()]/g, balance = 1;
+    const start = re.lastIndex = lastIndex;
+    for (let m; m = re.exec(simplified);) {
+        if (m[0] === '(') balance++;
+        else if (--balance === 0) {
+            re.lastIndex++;
+            break;
+        }
+    }
+    return {
+        start,
+        end: re.lastIndex,
+    }
+}
+
+/**
+ * @param {string} simplified 
+ * @param {Token[]} tokens 
+ * @param {{start: number, end: number}} simplified_range 
+ * @param {*[]} invalids
+ */
+function parseParameters(simplified, tokens, simplified_range, invalids) {
+    const decls = [
+        /[ X]+/g,
+        /@ *W( *\. *W)*( *\()?/g,
+        /M/g,
+        /W(?: *\. *W)*(?: *<.*?>)?(?: *\[ *\])*(?: +|( *\.\.\. *))W(?: *\[ *\])*( *,)?/g,  // parameter decl
+        /(\)|$)/g, // end of params
+    ];
+    const parameters = [];
+    /** @type {Modifier[]} */
+    const modifiers = [];
+    let lastIndex = simplified_range.start;
+    for(;;) {
+        /** @type {{idx:number, d: RegExp, m:RegExpMatchArray}} */
+        let best_match = null, next_best = null;
+        decls.find((d,idx) => {
+            d.lastIndex = lastIndex;
+            const m = d.exec(simplified);
+            if (!m) return;
+            if (m.index === lastIndex) {
+                best_match = {idx, d, m};
+                return true;
+            }
+            if (idx === 0) {
+                return;
+            }
+            if (!next_best || m.index < next_best.m.index) {
+                next_best = {idx, d, m};
+            }
+        });
+        if (!best_match) {
+            const errorToken = findToken(tokens, lastIndex);
+            const error = new ParseSyntaxError(null, modifiers.splice(0), errorToken);
+            invalids.push(error);
+            best_match = next_best;
+            if (!next_best) {
+                break;
+            }
+        }
+
+        lastIndex = best_match.d.lastIndex;
+
+        if (best_match.idx === 1) {
+            // annotation
+            const at = findToken(tokens, best_match.m.index);
+            const name = findToken(tokens, best_match.m.index + best_match.m[0].indexOf('W'));
+            const annotation = new Annotation(at, name);
+            modifiers.push(annotation);
+            if (best_match.m[0].endsWith('(')) {
+                lastIndex = parseToBracketEnd(simplified, lastIndex).end;
+            }
+        }
+        else if (best_match.idx === 2) {
+            // modifier
+            const modifier = findToken(tokens, best_match.m.index);
+            modifiers.push(modifier);
+        }
+        else if (best_match.idx === 3) {
+            // parameter
+            const name = findToken(tokens, best_match.m.index + best_match.m[0].lastIndexOf('W'));
+            const varargs = best_match.m[1] ? findToken(tokens, best_match.m.index + best_match.m[0].indexOf('...')) : null;
+            const comma = best_match.m[2] ? findToken(tokens, best_match.m.index + best_match.m[0].lastIndexOf(',')) : null;
+            const typetokens = [];
+            const first_type_token = findToken(tokens, best_match.m.index + best_match.m[0].indexOf('W'));
+            for (let t = first_type_token, i = tokens.indexOf(t); t !== name; t = tokens[++i]) {
+                if (t.simplified_text !== ' ')
+                    typetokens.push(t);
+            }
+            const param = new ParameterDeclaration(modifiers.splice(0), new TypeIdent(typetokens), varargs, name, comma);
+            parameters.push(param);
+        } else if (best_match.idx === 4) {
+            // end of parameters
+            break;
+        }
+    }
+
+    return parameters;
+}
+
+/**
+ * @param {Token[]} typelist_tokens 
+ */
+function parseTypeIdentList(typelist_tokens) {
+    // split the typelist into typetoken chunks, separated by commas
+    let typeargs_balance = 0, array_balance = 0;
+    /** @type {Token[][]} */
+    let types = [[]];
+    typelist_tokens.forEach(t => {
+        switch(t.text) {
+            case ' ':
+                if (types[0].length === 0) {
+                    return;
+                }
+                break;
+            case ',':
+                if (typeargs_balance <= 0 && array_balance <= 0) {
+                    while (types[0][types[0].length - 1].text === ' ') {
+                        types[0].pop();
+                    }
+                    typeargs_balance = array_balance = 0;
+                    types.unshift([]);
+                    return;
+                }
+                break;
+            case '<':
+                typeargs_balance++;
+                break;
+            case '>':
+                typeargs_balance--;
+                break;
+            case ']':
+                array_balance++;
+                break;
+            case '[':
+                array_balance--;
+                break;
+        }
+        types[0].push(t);
+    });
+
+    // remove any blank entries (start comma or sequential commas)
+    return types.filter(t => t.length).reverse().map(tokens => new TypeIdent(tokens));
+}
+
+/**
+ * @param {string} source 
+ */
+function parse(source) {
+    const re = /(\/\*[\d\D]*?\*\/)|(\/\*)|(\*\/)|((?:\/\/.*)|(?:\s+))|(".*?")|('.'?)|\b(package|import|class|enum|interface|extends|implements|throws)\b|\b(public|private|protected|static|final|abstract|native|volatile|transient|synchronized|strictfp)\b|(\.{3}|[@{}()<>,;?*\[\].])|\b(super|new)\b|\b([A-Za-z_]\w*)|(\d[\w.]*)/g;
+
+    let source_idx = 0, simplified_text_idx = 0;
+    /** @type {Token[]} */
+    let tokens = [];
+    function mapSimplified(
+        _,
+        mlc,
+        unterminated_mlc,
+        mlc_end,
+        slc_ws,
+        string,
+        char,
+        decl_keyword,
+        modifier,
+        symbol,
+        kw,
+        word
+        /* number, */
+    ) {
+        if (mlc) return 'X';//mlc.replace(/[^\n]+/g, '') || ' ';
+        if (unterminated_mlc) return ' ';
+        if (mlc_end) return ' ';
+        if (slc_ws) return ' '; //slc_ws.replace(/[^\n]+/g, '').replace(/  +/,' ') || ' ';
+        if (string) return 'S';
+        if (char) return 'C';
+        if (decl_keyword) return decl_keyword;
+        if (modifier) return 'M';
+        if (symbol) return symbol;
+        if (kw) return kw;
+        if (word) return 'W';
+        return 'N';
+
+    }
+    const simplified = source.replace(re, (...args) => {
+        let text = args[0];
+        let next_idx = source.indexOf(text, source_idx);
+
+        simplified_text_idx += (next_idx - source_idx);
+        source_idx = next_idx;
+
+        const simplified_text = mapSimplified.apply(null, args);
+        tokens.push(new Token(source_idx, text, simplified_text, simplified_text_idx));
+
+        source_idx += text.length;
+        simplified_text_idx += simplified_text.length;
+
+        return simplified_text;
+    });
+
+    // console.log(simplified);
+
+     const decls = [
+        / +/g,
+        /package +W(?: *\. *W)*( *;)?/g,
+        /import +(M +)?W(?: *\. *W)*( *\.\*)?( *;)?/g,
+        /@ *W( *\. *W)*( *\()?/g,
+        /M/g,
+        /(class|enum|interface|@ *interface) +W(.+?(?= *[a-z{]))/g, // type declaration
+        /(implements|extends|throws) +W(.+?(?= *[a-z{]))/g, // decl
+        /W(?: *\. *W)*(?: *<.*?>)?(?: *\[ *\])* +W(?: *\[ *\])*( *[=;(,])?/g,  // field/method
+        /W *\(/g,  // constructor
+        /[{}]/g,  // scope
+        /X/g,   // multi-line comment
+        /<.*?>(?= *[WM@])/g,   // type variables
+        /$/g, // end of file
+    ]
+    let lastIndex = 0;
+    let loc = ['base'];
+    let package_decl = null;
+    let imports = [];
+    let modifiers = [];
+    let types = [];
+    let invalids = [];
+    let lastMLC = null;
+    /** @type {TypeDeclaration[]} */
+    let type_stack = [null];
+
+    for(;;) {
+        /** @type {{idx:number, d: RegExp, m:RegExpMatchArray}} */
+        let best_match = null, next_best = null;
+        decls.find((d,idx) => {
+            d.lastIndex = lastIndex;
+            const m = d.exec(simplified);
+            if (!m) return;
+            if (m.index === lastIndex) {
+                best_match = {idx, d, m};
+                return true;
+            }
+            if (idx === 0) {
+                return;
+            }
+            if (!next_best || m.index < next_best.m.index) {
+                next_best = {idx, d, m};
+            }
+        });
+        if (!best_match) {
+            const errorToken = findToken(tokens, lastIndex);
+            const error = new ParseSyntaxError(lastMLC, modifiers.splice(0), errorToken);
+            invalids.push(error);
+            lastMLC = null;
+            console.log(simplified.slice(lastIndex, lastIndex + 100));
+            best_match = next_best;
+            if (!next_best) {
+                break;
+            }
+        }
+
+        lastIndex = best_match.d.lastIndex;
+
+        function parseToExpressionEnd() {
+            // parse expression
+            let re = /[(){};]/g, balance = [0,0];
+            re.lastIndex = lastIndex;
+            for (let m; m = re.exec(simplified);) {
+                if (m[0] === '{') balance[0]++;
+                else if (m[0] === '(') balance[1]++;
+                else if (m[0] === '}') balance[0]--;
+                else if (m[0] === ')') balance[1]--;
+                else if (balance[0] <= 0 && balance[1] <= 0) {
+                    break;
+                }
+            }
+            // console.log(simplified.slice(lastIndex, re.lastIndex));
+            lastIndex = re.lastIndex;
+        }
+
+        if (best_match.idx === 1) {
+            // package - map all the name parts
+            const nameparts = [];
+            for (let m, re=/W/g; m = re.exec(best_match.m[0]); ) {
+                const ident = findToken(tokens, best_match.m.index + m.index);
+                nameparts.push(ident);
+            }
+            const semicolon = best_match.m[1] ? findToken(tokens, best_match.m.index + best_match.m[0].length - 1) : null;
+            if (!package_decl) {
+                package_decl = new PackageDeclaration(lastMLC, modifiers.splice(0), nameparts, semicolon);
+            }
+            lastMLC = null;
+        }
+        if (best_match.idx === 2) {
+            // import - map all the name parts
+            const nameparts = [];
+            for (let m, re=/W/g; m = re.exec(best_match.m[0]); ) {
+                const ident = findToken(tokens, best_match.m.index + m.index);
+                nameparts.push(ident);
+            }
+            const static = best_match.m[1] ? findToken(tokens, best_match.m.index + best_match.m[0].indexOf('M')) : null;
+            const asterisk = best_match.m[2] ? findToken(tokens, best_match.m.index + best_match.m[0].lastIndexOf('*')) : null
+            const semicolon = best_match.m[3] ? findToken(tokens, best_match.m.index + best_match.m[0].lastIndexOf(';')) : null;
+            let import_decl = new ImportDeclaration(lastMLC, modifiers.splice(0), nameparts, static, asterisk, semicolon);
+            imports.push(import_decl);
+            lastMLC = null;
+        }
+        if (best_match.idx === 3) {
+            // annotation
+            const at = findToken(tokens, best_match.m.index);
+            const name = findToken(tokens, best_match.m.index + best_match.m[0].indexOf('W'));
+            const annotation = new Annotation(at, name);
+            modifiers.push(annotation);
+            if (best_match.m[0].endsWith('(')) {
+                lastIndex = parseToBracketEnd(simplified, lastIndex).end;
+            }
+        }
+        if (best_match.idx === 4) {
+            // modifier
+            const modifier = findToken(tokens, best_match.m.index);
+            modifiers.push(modifier);
+        }
+
+        if (best_match.idx === 5) {
+            // type declaration
+            const name = findToken(tokens, best_match.m.index + best_match.m[0].lastIndexOf('W'));
+            /** @type {'class'|'interface'|'enum'|'@interface'} */
+            // @ts-ignore
+            const kind = best_match.m[1].replace(/ /g, '');
+            const type = new TypeDeclaration(type_stack[0], lastMLC, modifiers.splice(0), kind, name);
+            lastMLC = null;
+            types.push(type);
+            type_stack.unshift(type);
+            loc.unshift('typedecl');
+        }
+
+        if (best_match.idx === 6) {
+            // extends/implements/throws
+            const decl_kw = findToken(tokens, best_match.m.index);
+            const startidx = tokens.indexOf(findToken(tokens, best_match.m.index + best_match.m[0].indexOf('W')));
+            const endidx = tokens.indexOf(findToken(tokens,best_match.m.index + best_match.m[0].length - 1));
+            const typelist = parseTypeIdentList(tokens.slice(startidx, endidx + 1));
+            switch(decl_kw.text) {
+                case 'throws':
+                    break;
+                case 'extends':
+                case 'implements':
+                    if (loc[0] === 'typedecl') {
+                        type_stack[0].super_declarations.push({ decl_kw, typelist });
+                    }
+            }
+        }
+
+        if (best_match.idx === 7) {
+            // field or method
+            const name = findToken(tokens, best_match.m.index + best_match.m[0].lastIndexOf('W'));
+            const typetokens = [];
+            for (let t = findToken(tokens, best_match.m.index), i = tokens.indexOf(t); t !== name; t = tokens[++i]) {
+                if (t.simplified_text !== ' ')
+                    typetokens.push(t);
+            }
+            let parameters, equals_comma_sc = null;
+            switch (best_match.m[0].slice(-1)) {
+                case '(':
+                    // method
+                    let params_source_range = parseToBracketEnd(simplified, lastIndex);
+                    lastIndex = params_source_range.end;
+                    parameters = parseParameters(simplified, tokens, params_source_range, invalids);
+                    break;
+                case '=':
+                    // initialised field
+                    equals_comma_sc = findToken(tokens, best_match.m.index + best_match.m[0].length);
+                    parseToExpressionEnd();
+                    break;
+                case ',':
+                    // multi-declaration field
+                    equals_comma_sc = findToken(tokens, best_match.m.index + best_match.m[0].length);
+                    throw new Error('not implemented');
+                case ';':
+                    // single field
+                    equals_comma_sc = findToken(tokens, best_match.m.index + best_match.m[0].length);
+                    break;
+                default:
+                    // invalid - but treat as a single field
+                    break;
+            }
+            if (type_stack[0]) {
+                const fmc = new FMCDeclaration(type_stack[0], lastMLC, modifiers.splice(0), best_match.m[0].endsWith('(') ? 'method' : 'field', name, new TypeIdent(typetokens), equals_comma_sc, parameters);
+                type_stack[0].declarations.push(fmc);
+            }
+            lastMLC = null;
+        }
+
+        if (best_match.idx === 8) {
+            // constructor (if the name matches the type)
+            let params_source_range = parseToBracketEnd(simplified, lastIndex);
+            lastIndex = params_source_range.end;
+            const parameters = parseParameters(simplified, tokens, params_source_range, invalids);
+            const name = findToken(tokens, best_match.m.index);
+            if (type_stack[0] && name.text === type_stack[0].name.text) {
+                const fmc = new FMCDeclaration(type_stack[0], lastMLC, modifiers.splice(0), 'constructor', name, null, null, parameters);
+                type_stack[0].declarations.push(fmc);
+            } else {
+                invalids.push(new ParseSyntaxError(lastMLC, modifiers.splice(0), name));
+            }
+            lastMLC = null;
+        }
+
+        if (best_match.idx === 9) {
+            // open/close scope
+            if (best_match.m[0] === '{') {
+                if (loc[0] === 'typedecl') loc[0] = 'typebody';
+                else if (loc[0] === 'typebody') {
+                    // static initer / method body
+                    let re = /[{}]/g, balance = 1;
+                    re.lastIndex = lastIndex;
+                    for (let m; m = re.exec(simplified);) {
+                        if (m[0] === '{') balance++;
+                        else if (--balance === 0) {
+                            re.lastIndex++;
+                            break;
+                        }
+                    }
+                    lastIndex = re.lastIndex;
+                }
+            } else {
+                // end scope
+                if (/^type/.test(loc[0])) {
+                    loc.shift();
+                    type_stack.shift();
+                }
+            }
+        }
+
+        if (best_match.idx === 10) {
+            // mlc
+            lastMLC = findToken(tokens, best_match.m.index);
+        }
+
+        if (best_match.idx === 11) {
+            // type parameters
+            const open = findToken(tokens, best_match.m.index);
+            const close = findToken(tokens, best_match.m.index + best_match.m[0].length - 1);
+            modifiers.push(new TypeParameters(open, close));
+        }
+
+        if (best_match.idx === 12) {
+            // end of file
+            break;
+        }
+    }
+
+    return new ParseResult(package_decl, imports, types, invalids);
+}
+
+module.exports = {
+    Annotation,
+    Declaration,
+    FMCDeclaration,
+    ImportDeclaration,
+    PackageDeclaration,
+    parse,
+    ParseProblem,
+    ParseResult,
+    ProblemSeverity,
+    Token,
+    TypeDeclaration,
+    TypeParameters,
+}
diff --git a/langserver/java/parsetypes/annotation.js b/langserver/java/parsetypes/annotation.js
new file mode 100644
index 0000000..5087c2d
--- /dev/null
+++ b/langserver/java/parsetypes/annotation.js
@@ -0,0 +1,16 @@
+/**
+ * @typedef {import('./token')} Token
+ */
+
+ class Annotation {
+    /**
+     * @param {Token} at 
+     * @param {Token} name 
+     */
+    constructor(at, name) {
+        this.at = at;
+        this.name = name;
+    }
+}
+
+module.exports = Annotation;
diff --git a/langserver/java/parsetypes/declaration.js b/langserver/java/parsetypes/declaration.js
new file mode 100644
index 0000000..0ad50ae
--- /dev/null
+++ b/langserver/java/parsetypes/declaration.js
@@ -0,0 +1,49 @@
+const Token = require('./token');
+/**
+ * @typedef {import('./modifier')} Modifier
+ * @typedef {import('./type')} TypeDeclaration
+ */
+
+/**
+ * Base class for Java declarations.
+ */
+class Declaration {
+    /**
+     * @param {TypeDeclaration} owner_type the type this declaration belongs to (if any)
+     * @param {Token} docs JavaDocs associated with the declaration
+     * @param {Modifier[]} modifiers annotations, modifier keywords and type parameters
+     */
+    constructor(owner_type, docs, modifiers) {
+        this.owner_type = owner_type;
+        this.docs = docs;
+        this.modifiers = modifiers;
+    }
+
+    /**
+     * returns the raw JavaDoc string or an empty string if no doc is present
+     */
+    getDocString() {
+        return this.docs ? this.docs.text : '';
+    }
+
+    /**
+     * Returns the raw access modifier text values
+     * @returns {string[]}
+     */
+    getAccessModifierValues() {
+        // @ts-ignore
+        return this.modifiers.filter(m => m instanceof Token).map(t => t.text);
+    }
+
+    /**
+     * Finds the token matching the specified modifier
+     * @param {string} name 
+     * @returns {Token}
+     */
+    findModifier(name) {
+        // @ts-ignore
+        return this.modifiers.find(m => (m instanceof Token) && (m.text === name));
+    }
+}
+
+module.exports = Declaration;
diff --git a/langserver/java/parsetypes/fmc.js b/langserver/java/parsetypes/fmc.js
new file mode 100644
index 0000000..f977e3f
--- /dev/null
+++ b/langserver/java/parsetypes/fmc.js
@@ -0,0 +1,90 @@
+/**
+ * @typedef {import('./modifier')} Modifier
+ * @typedef {import('./parameter')} ParameterDeclaration
+ * @typedef {import('./token')} Token
+ * @typedef {import('./type')} TypeDeclaration
+ * @typedef {import('./typeident')} TypeIdent
+ */
+const Declaration = require('./declaration');
+const ParseProblem = require('./parse-problem');
+const ProblemSeverity = require('./problem-severity');
+
+/**
+ * Field, method or constructor declaration
+ */
+class FMCDeclaration extends Declaration {
+    /**
+     * 
+     * @param {TypeDeclaration} owner_type 
+     * @param {Token} docs 
+     * @param {Modifier[]} modifiers 
+     * @param {'field'|'method'|'constructor'} kind 
+     * @param {Token} name 
+     * @param {TypeIdent} type 
+     * @param {Token} equals_comma_sc 
+     * @param {ParameterDeclaration[]} parameters 
+     */
+    constructor(owner_type, docs, modifiers, kind, name, type, equals_comma_sc, parameters) {
+        super(owner_type, docs, modifiers);
+        this.kind = kind;
+        this.name = name;
+        this.type = type;
+        this.equals_comma_sc = equals_comma_sc;
+        this.parameters = parameters || [];
+    }
+
+    validate() {
+        const checkDuplicateParameterNames = () => {
+            const done = new Set();
+            return this.parameters
+                .filter(p => {
+                    if (done.has(p.name.text)) {
+                        return true;
+                    }
+                    done.add(p.name.text);
+                })
+                .map(p =>
+                    new ParseProblem(p.name, `Duplicate parameter name: '${p.name.text}'`, ProblemSeverity.Error)
+                );
+        };
+        const checkParameterCommas = () => {
+            const last_param_idx = this.parameters.length - 1;
+            return this.parameters.map((p, idx) => {
+                if ((idx < last_param_idx) && !p.comma) {
+                    return new ParseProblem(p.lastToken(), 'Missing comma', ProblemSeverity.Error);
+                }
+                else if ((idx === last_param_idx) && p.comma) {
+                    return ParseProblem.syntaxError(p.comma);
+                }
+            });
+        }
+        const checkFieldSemicolon = () => {
+            if (this.kind === 'field') {
+                if (!this.equals_comma_sc) {
+                    return new ParseProblem(this.name, `Missing operator or semicolon`, ProblemSeverity.Error);
+                }
+            }
+            return null;
+        }
+        const checkVarargsIsLastParameter = () => {
+            return this.parameters
+                .slice(0, -1)
+                .filter(p => p.varargs)
+                .map(p =>
+                    new ParseProblem(p.varargs, 'A variable arity parameter must be declared last', ProblemSeverity.Error)
+                );
+        };
+        const problems = [
+            ...ParseProblem.checkAccessModifiers(this.modifiers, this.kind),
+            ...ParseProblem.checkDuplicateModifiers(this.modifiers),
+            ...ParseProblem.checkConflictingModifiers(this.modifiers),
+            ...checkParameterCommas(),
+            ...checkDuplicateParameterNames(),
+            ...checkVarargsIsLastParameter(),
+            checkFieldSemicolon(),
+        ];
+        return problems;
+    }
+}
+
+module.exports = FMCDeclaration;
diff --git a/langserver/java/parsetypes/import.js b/langserver/java/parsetypes/import.js
new file mode 100644
index 0000000..eb301a9
--- /dev/null
+++ b/langserver/java/parsetypes/import.js
@@ -0,0 +1,68 @@
+const Declaration = require('./declaration');
+const ParseProblem = require('./parse-problem');
+const Token = require('./token');
+const TypeParameters = require('./type-parameters');
+
+/**
+ * @typedef {import('./modifier')} Modifier
+ */
+
+class ImportDeclaration extends Declaration {
+    /**
+     * @param {Token} docs 
+     * @param {Modifier[]} modifiers 
+     * @param {Token[]} nameparts 
+     * @param {Token} static_
+     * @param {Token} asterisk
+     * @param {Token} semicolon
+     */
+    constructor(docs, modifiers, nameparts, static_, asterisk, semicolon) {
+        super(null, docs, modifiers);
+        this.nameparts = nameparts;
+        this.static_ = static_;
+        this.asterisk = asterisk;
+        this.semicolon = semicolon;
+    }
+
+    /**
+     * Returns the dotted portion of the import declaration (excluding any demand-load part)
+     */
+    getDottedName() {
+        return this.nameparts.map(x => x.text).join('.');
+    }
+
+    lastToken() {
+        return this.semicolon || this.asterisk || this.nameparts.slice(-1)[0];
+    }
+
+    validate() {
+        const checkModifierIsStatic = () => {
+            if (this.static_ && this.static_.text !== 'static') {
+                return ParseProblem.syntaxError(this.static_);
+            }
+        }
+
+        const checkNoInvalidModifiers = () => {
+            return this.modifiers.map(modifier => {
+                if (modifier instanceof Token) {
+                    return ParseProblem.syntaxError(modifier);
+                }
+                if (modifier instanceof TypeParameters) {
+                    return ParseProblem.syntaxError(modifier.open);
+                }
+            })
+        }
+
+        /** @type {ParseProblem[]} */
+        const problems = [
+            checkModifierIsStatic(),
+            ...ParseProblem.checkNonKeywordIdents(this.nameparts),
+            ParseProblem.checkSemicolon(this),
+            ...checkNoInvalidModifiers(),
+        ];
+
+        return problems;
+    }
+}
+
+module.exports = ImportDeclaration;
diff --git a/langserver/java/parsetypes/modifier.js b/langserver/java/parsetypes/modifier.js
new file mode 100644
index 0000000..f11b850
--- /dev/null
+++ b/langserver/java/parsetypes/modifier.js
@@ -0,0 +1,15 @@
+/**
+ * @typedef {import('./annotation')} Annotation
+ * @typedef {import('./type-parameters')} TypeParameters
+ * @typedef {import('./token')} Token
+ * 
+ * Each Modifier is one of
+ *   - a token representing a modifier keyword (e.g public, static, etc)
+ *   - an Annotation (eg. @Override)
+ *   - or a TypeParameters section (eg <T extends Object>)
+ * These can typically appear in any order before a declaration
+ *
+ * @typedef {Token|Annotation|TypeParameters} Modifier
+ */
+
+ module.exports = {}
diff --git a/langserver/java/parsetypes/package.js b/langserver/java/parsetypes/package.js
new file mode 100644
index 0000000..126802a
--- /dev/null
+++ b/langserver/java/parsetypes/package.js
@@ -0,0 +1,39 @@
+const Declaration = require('./declaration');
+const ParseProblem = require('./parse-problem');
+/**
+ * @typedef {import('./modifier')} Modifier
+ * @typedef {import('./token')} Token
+ */
+
+class PackageDeclaration extends Declaration {
+    /**
+     * @param {Token} docs 
+     * @param {Modifier[]} modifiers 
+     * @param {Token[]} nameparts 
+     * @param {Token} semicolon
+     */
+    constructor(docs, modifiers, nameparts, semicolon) {
+        super(null, docs, modifiers);
+        this.nameparts = nameparts;
+        this.semicolon = semicolon;
+    }
+
+    dottedName() {
+        return this.nameparts.map(t => t.text).join('.');
+    }
+
+    lastToken() {
+        return this.semicolon || this.nameparts.slice(-1)[0];
+    }
+
+    validate() {
+        /** @type {ParseProblem[]} */
+        const problems = [
+            ParseProblem.checkSemicolon(this),
+            ...ParseProblem.checkNonKeywordIdents(this.nameparts),
+        ];
+        return problems;
+    }
+}
+
+module.exports = PackageDeclaration;
diff --git a/langserver/java/parsetypes/parameter.js b/langserver/java/parsetypes/parameter.js
new file mode 100644
index 0000000..6cb911d
--- /dev/null
+++ b/langserver/java/parsetypes/parameter.js
@@ -0,0 +1,33 @@
+const Declaration = require('./declaration');
+
+/**
+ * @typedef {import('./modifier')} Modifier
+ * @typedef {import('./typeident')} TypeIdent
+ * @typedef {import('./token')} Token
+ */
+
+ /**
+  * A single parameter declaration
+  */
+ class ParameterDeclaration extends Declaration {
+    /**
+     * @param {Modifier[]} modifiers 
+     * @param {TypeIdent} type 
+     * @param {Token} varargs 
+     * @param {Token} name 
+     * @param {Token} comma
+     */
+    constructor(modifiers, type, varargs, name, comma) {
+        super(null, null, modifiers);
+        this.name = name;
+        this.type = type;
+        this.varargs = varargs;
+        this.comma = comma;
+    }
+
+    lastToken() {
+        return this.comma || this.name;
+    }
+}
+
+module.exports = ParameterDeclaration;
diff --git a/langserver/java/parsetypes/parse-error.js b/langserver/java/parsetypes/parse-error.js
new file mode 100644
index 0000000..892511e
--- /dev/null
+++ b/langserver/java/parsetypes/parse-error.js
@@ -0,0 +1,29 @@
+const Declaration = require('./declaration');
+const ParseProblem = require('./parse-problem');
+/**
+ * @typedef {import('./modifier')} Modifier
+ * @typedef {import('./token')} Token
+ */
+
+class ParseSyntaxError extends Declaration {
+    /**
+     * @param {Token} docs 
+     * @param {Modifier[]} modifiers 
+     * @param {Token} errorToken 
+     */
+    constructor(docs, modifiers, errorToken) {
+        super(null, docs, modifiers);
+        this.errorToken = errorToken;
+    }
+
+    validate() {
+        if (!this.errorToken) {
+            return [];
+        }
+        return [
+            ParseProblem.syntaxError(this.errorToken),
+        ]
+    }
+}
+
+module.exports = ParseSyntaxError;
diff --git a/langserver/java/parsetypes/parse-problem.js b/langserver/java/parsetypes/parse-problem.js
new file mode 100644
index 0000000..481260c
--- /dev/null
+++ b/langserver/java/parsetypes/parse-problem.js
@@ -0,0 +1,134 @@
+const ProblemSeverity = require('./problem-severity');
+const Token = require('./token');
+
+/**
+ * @typedef {import('./import')} ImportDeclaration
+ * @typedef {import('./modifier')} Modifier
+ * @typedef {import('./package')} PackageDeclaration
+ * @typedef {import('./problem-severity').Severity} Severity
+ */
+
+
+class ParseProblem {
+    /**
+     * @param {Token|Token[]} token 
+     * @param {string} message 
+     * @param {Severity} severity 
+     */
+    constructor(token, message, severity) {
+        this.startIdx = (Array.isArray(token) ? token[0] : token).source_idx;
+        const lastToken = (Array.isArray(token) ? token[token.length - 1] : token);
+        this.endIdx = lastToken.source_idx + lastToken.text.length;
+        this.message = message;
+        this.severity = severity;
+    }
+
+    /**
+     * @param {Modifier[]} mods 
+     */
+    static checkDuplicateModifiers(mods) {
+        const done = new Set();
+        const res = [];
+        for (let mod of mods) {
+            if (mod instanceof Token) {
+                if (done.has(mod.text)) {
+                    res.push(new ParseProblem(mod, `Duplicate modifier: ${mod.text}`, ProblemSeverity.Error));
+                }
+                done.add(mod.text);
+            }
+        }
+        return res;
+    }
+
+    static checkConflictingModifiers(mods) {
+        const modmap = new Map();
+        let res = [];
+        mods.filter(m => m instanceof Token).forEach(m => modmap.set(m.text, m));
+        const names = [...modmap.keys()];
+        const visibilities = names.filter(m => /^(public|private|protected)$/.test(m));
+        if (visibilities.length > 1) {
+            const visnames = visibilities.map(m => `'${m}'`).join(', ').replace(/, (?='\w+'$)/, ' and ');
+            res = visibilities.map(m => new ParseProblem(modmap.get(m), `Conflicting modifiers: ${visnames}`, ProblemSeverity.Error));
+        }
+        if (names.includes('abstract')) {
+            if (names.includes('final')) {
+                res.push(new ParseProblem(modmap.get('final'), `Declarations cannot be both 'abstract' and 'final`, ProblemSeverity.Error));
+            }
+            if (names.includes('native')) {
+                res.push(new ParseProblem(modmap.get('native'), `Declarations cannot be both 'abstract' and 'native`, ProblemSeverity.Error));
+            }
+        }
+        return res;
+    }
+
+    /**
+     * @param {Modifier[]} mods 
+     * @param {'class'|'interface'|'enum'|'@interface'|'field'|'method'|'constructor'|'initializer'} decl_kind
+     */
+    static checkAccessModifiers(mods, decl_kind) {
+        let valid_mods = /^$/;
+        switch (decl_kind) {
+            case 'class': valid_mods = /^(public|final|abstract|strictfp)$/; break;
+            case 'interface': valid_mods = /^(public|abstract|strictfp)$/; break;
+            case '@interface': valid_mods = /^(public)$/; break;
+            case 'enum': valid_mods = /^(public|final)$/; break;
+            case 'field': valid_mods = /^(public|private|protected|static|final|volatile|transient)$/; break;
+            case 'method': valid_mods = /^(public|private|protected|static|final|abstract|native|strictfp|synchronized)$/; break;
+            case 'constructor': valid_mods = /^(public|protected|native)$/; break;
+            case 'initializer': valid_mods = /^(static)$/; break;
+        }
+        const problems = [];
+        for (let mod of mods) {
+            if (mod instanceof Token) {
+                if (!valid_mods.test(mod.text)) {
+                    problems.push(new ParseProblem(mod, `'${mod.text}' is not a valid modifier for ${decl_kind} type declarations`, ProblemSeverity.Warning));
+                }
+                const redundant = (mod.text === 'abstract' && decl_kind === 'interface')
+                    || (mod.text === 'final' && decl_kind === 'enum');
+                if (redundant) {
+                    problems.push(new ParseProblem(mod, `'${mod.text}' is redundant for a ${decl_kind} declaration`, ProblemSeverity.Hint));
+                }
+            }
+        }
+        return problems;
+    }
+
+    /**
+     * @param {PackageDeclaration|ImportDeclaration} o 
+     */
+    static checkSemicolon(o) {
+        if (!o.semicolon) {
+            const lastToken = o.lastToken();
+            return new ParseProblem(lastToken, 'Missing operator or semicolon',  ProblemSeverity.Error);
+        }
+    }
+
+    /**
+     * @param {Token[]} tokens 
+     */
+    static checkNonKeywordIdents(tokens) {
+        const res = [];
+        const KEYWORDS = /^(abstract|assert|break|case|catch|class|const|continue|default|do|else|enum|extends|final|finally|for|goto|if|implements|import|interface|native|new|package|private|protected|public|return|static|strictfp|super|switch|synchronized|throw|throws|transient|try|volatile|while)$/;
+        const PRIMITIVE_TYPE_KEYWORDS = /^(int|boolean|byte|char|double|float|long|short|void)$/
+        const LITERAL_VALUE_KEYWORDS = /^(this|true|false|null)$/;
+        const OPERATOR_KEYWORDS = /^(instanceof)$/;
+        for (let token of tokens) {
+            let iskw = KEYWORDS.test(token.text) || PRIMITIVE_TYPE_KEYWORDS.test(token.text) || LITERAL_VALUE_KEYWORDS.test(token.text) || OPERATOR_KEYWORDS.test(token.text);
+            if (iskw) {
+                const problem = new ParseProblem(token, `'${token.text}' is a keyword and cannot be used as an identifier`,  ProblemSeverity.Error);
+                res.push(problem);
+            }
+        }
+        return res;
+    }
+
+    /**
+     * @param {Token} token
+     */
+    static syntaxError(token) {
+        if (!token) return null;
+        return new ParseProblem(token, 'Unsupported, invalid or incomplete declaration', ProblemSeverity.Error);
+    }
+}
+
+module.exports = ParseProblem;
diff --git a/langserver/java/parsetypes/parse-result.js b/langserver/java/parsetypes/parse-result.js
new file mode 100644
index 0000000..d3ad84a
--- /dev/null
+++ b/langserver/java/parsetypes/parse-result.js
@@ -0,0 +1,24 @@
+/**
+ * @typedef {import('./import')} ImportDeclaration
+ * @typedef {import('./package')} PackageDeclaration
+ * @typedef {import('./parse-error')} ParseSyntaxError
+ * @typedef {import('./type')} TypeDeclaration
+ */
+
+ class ParseResult {
+    /**
+     * 
+     * @param {PackageDeclaration} package_decl 
+     * @param {ImportDeclaration[]} imports 
+     * @param {TypeDeclaration[]} types 
+     * @param {ParseSyntaxError[]} invalids
+     */
+    constructor(package_decl, imports, types, invalids) {
+        this.package = package_decl;
+        this.imports = imports;
+        this.types = types;
+        this.invalids = invalids;
+    }
+}
+
+module.exports = ParseResult;
diff --git a/langserver/java/parsetypes/problem-severity.js b/langserver/java/parsetypes/problem-severity.js
new file mode 100644
index 0000000..2e6b7ab
--- /dev/null
+++ b/langserver/java/parsetypes/problem-severity.js
@@ -0,0 +1,8 @@
+/**
+ * @typedef {1|2|3|4} Severity
+ * @type {{ Error:1, Warning:2, Information:3, Hint:4 }} 
+ * these match the vscode DiagnosticSeverity values
+*/
+const ProblemSeverity = { Error:1, Warning:2, Information:3, Hint:4 };
+
+module.exports = ProblemSeverity;
diff --git a/langserver/java/parsetypes/resolved-import.js b/langserver/java/parsetypes/resolved-import.js
new file mode 100644
index 0000000..fc11177
--- /dev/null
+++ b/langserver/java/parsetypes/resolved-import.js
@@ -0,0 +1,45 @@
+/**
+ * @typedef {import('./import')} ImportDeclaration
+ */
+
+ /**
+  * Class representing a resolved import.
+  * 
+  * Each instance holds an array of types that would be resolved by the specified import.
+  * Each type is mapped to an MTI which lists the implementation details of the type (fields, methods, etc).
+  * 
+  */
+ class ResolvedImport {
+    /**
+     * @param {ImportDeclaration} import_decl 
+     * @param {RegExpMatchArray} matches 
+     * @param {'owner-package'|'import'|'implicit-import'} import_kind;
+     */
+    constructor(import_decl, matches, typemap, import_kind) {
+        /**
+         * The associated import declaration.
+         * - this value is null for owner-package and implicit-imports
+         */
+        this.import = import_decl;
+
+        /**
+         * Array of fully qualified type names in JRE format resolved in this import
+         */
+        this.fullyQualifiedNames = Array.from(matches);
+
+        /**
+         * THe map of fully-qualified type names to MTIs
+         */
+        this.types = new Map(matches.map(name => [name, typemap.get(name)]));
+
+        /**
+         * What kind of import this is:
+         *   - `"owner-package"`: types that are implicitly imported from the same package as the declared module
+         *   - `"import"`: types that are inclduded via an import declaration specified in the module
+         *   - `"implicit-import"`: types that are included without any explicit import (`java.lang.*` for example)
+         */
+        this.import_kind = import_kind;
+    }
+}
+
+module.exports = ResolvedImport;
diff --git a/langserver/java/parsetypes/resolved-type.js b/langserver/java/parsetypes/resolved-type.js
new file mode 100644
index 0000000..799cfda
--- /dev/null
+++ b/langserver/java/parsetypes/resolved-type.js
@@ -0,0 +1,105 @@
+/**
+ * @typedef {import('./token')} Token
+ * @typedef {import('./type')} TypeDeclaration
+ */
+
+/**
+ * Class representing a parsed and resolved type
+ * 
+ * Each `ResolvedType` consists of a linked set of parsed `TypeParts` and an array dimensions count.
+ * Each `TypePart` is a single dotted type with optional type arguments.
+ * 
+ * When parsing, the first type part matches all dotted idents up to the first type with arguments - after
+ * that, there is a single type part for each further enclosed type.
+ * 
+ * Examples:
+ * 
+ *   int -> one TypePart, arrdims = 0
+ *   int[][] -> one TypePart, arrdims = 2
+ *   List<String> -> one type part with one typeargs entry
+ *   List<String>.InnerType -> two type parts (List<String> / InnerType)
+ *   List<String>.InnerType.AnotherInner -> three type parts (List<String> / InnerType / AnotherInner)
+ *   java.util.List<String>.InnerType<Object>.AnotherInner -> three type parts (java.util.List<String> / InnerType<Object> / AnotherInner)
+ *   java.util.List.InnerType.AnotherInner -> one type part
+ * 
+ * The reason for the non-obvious splitting is that the first part of the type could incorporate a package name - we
+ * cannot tell which parts of the name are packages and which are types/enclosed types until we try to resolve it.
+ * But type arguments are only allowed on types, so any qualifiers that appear after type arguments can only be a type and
+ * so we split on each single identifier.
+ *
+ */
+class ResolvedType {
+
+    static TypePart = class TypePart {
+        /**
+         * The list of type arguments
+         * @type {ResolvedType[]}
+         */
+        typeargs = null;
+
+        /**
+         * The outer type if this is an enclosed generic type
+         * @type {ResolvedType.TypePart}
+         */
+        outer = null;
+        inner = null;
+
+        /**
+         * @param {ResolvedType} owner
+         * @param {string} name
+         * @param {ResolvedType.TypePart} outer
+         */
+        constructor(owner, name, outer) {
+            this.owner = owner;
+            this.name = name;
+            this.outer = outer;
+        }
+
+        get label() {
+            return this.name + (this.typeargs ? `<${this.typeargs.map(arg => arg.label).join(',')}>` : '');
+        }
+    }
+
+    /** @type {ResolvedType.TypePart[]} */
+    parts = [];
+
+    /**
+     * number of array dimensions for this type
+     */
+    arrdims = 0;
+
+    /**
+     * Error reason if parsing failed.
+     */
+    error = '';
+
+    /**
+     * The resolved MTIs that match this type. This will be an empty array if the type cannot be found.
+     * @type {import('../mti').Type[]}
+     */
+    mtis = [];
+
+    /**
+     * During parsing, add a new type part
+     * @param {string} [name] 
+     * @param {ResolvedType.TypePart} [outer] 
+     */
+    addTypePart(name = '', outer = null) {
+        const p = new ResolvedType.TypePart(this, name, outer);
+        this.parts.push(p);
+        return p;
+    }
+
+    getDottedRawType() {
+        // most types will only have one part
+        if (this.parts.length === 1)
+            return this.parts[0].name;
+        return this.parts.map(p => p.name).join('.');
+    }
+
+    get label() {
+        return this.parts.map(p => p.label).join('.') + '[]'.repeat(this.arrdims);
+    }
+};
+
+module.exports = ResolvedType;
diff --git a/langserver/java/parsetypes/token.js b/langserver/java/parsetypes/token.js
new file mode 100644
index 0000000..e3d3c9c
--- /dev/null
+++ b/langserver/java/parsetypes/token.js
@@ -0,0 +1,17 @@
+class Token {
+    /**
+     * 
+     * @param {number} source_idx 
+     * @param {string} text 
+     * @param {string} simplified_text 
+     * @param {number} simplified_text_idx 
+     */
+    constructor(source_idx, text, simplified_text, simplified_text_idx) {
+        this.source_idx = source_idx;
+        this.text = text;
+        this.simplified_text = simplified_text;
+        this.simplified_text_idx = simplified_text_idx;
+    }
+}
+
+module.exports = Token;
diff --git a/langserver/java/parsetypes/type-parameters.js b/langserver/java/parsetypes/type-parameters.js
new file mode 100644
index 0000000..c558923
--- /dev/null
+++ b/langserver/java/parsetypes/type-parameters.js
@@ -0,0 +1,17 @@
+/**
+ * @typedef {import('./token')} Token
+ */
+
+class TypeParameters {
+    /**
+     * 
+     * @param {Token} open 
+     * @param {Token} close 
+     */
+    constructor(open, close) {
+        this.open = open;
+        this.close = close;
+    }
+}
+
+module.exports = TypeParameters;
diff --git a/langserver/java/parsetypes/type.js b/langserver/java/parsetypes/type.js
new file mode 100644
index 0000000..d24fba2
--- /dev/null
+++ b/langserver/java/parsetypes/type.js
@@ -0,0 +1,229 @@
+const Declaration = require('./declaration');
+const ParseProblem = require('./parse-problem');
+const ProblemSeverity = require('./problem-severity');
+const ResolvedImport = require('../import-resolver').ResolvedImport;
+const { resolveTypeIdents } = require('../type-resolver');
+const Token = require('./token');
+
+/**
+ * @typedef {import('./import')} ImportDeclaration
+ * @typedef {import('./fmc')} FMCDeclaration
+ * @typedef {import('./modifier')} Modifier
+ * @typedef {import('./parameter')} ParameterDeclaration
+ * @typedef {import('./typeident')} TypeIdent
+ */
+
+/**
+ * Represents a single Java type (class, interface, enum or @-interface) declaration
+ */
+class TypeDeclaration extends Declaration {
+    /**
+     *
+     * @param {TypeDeclaration} owner_type
+     * @param {Token} docs
+     * @param {Modifier[]} modifiers
+     * @param {'class'|'interface'|'enum'|'@interface'} kind
+     * @param {Token} name
+     */
+    constructor(owner_type, docs, modifiers, kind, name) {
+        super(owner_type, docs, modifiers);
+        this.kind = kind;
+        this.name = name;
+        /** @type {FMCDeclaration[]} */
+        this.declarations = [];
+        /** @type {{decl_kw:Token, typelist:TypeIdent[]}[]} */
+        this.super_declarations = [];
+    }
+
+    /**
+     * returns the $-qualified name of this type (excluding package)
+     */
+    qualifiedName() {
+        if (!this.owner_type) {
+            // top-level type
+            return this.name.text;
+        }
+        const parts = [];
+        for (let t = this; t;) {
+            parts.unshift(t.name.text);
+            // @ts-ignore
+            t = t.owner_type;
+        }
+        return parts.join('$');
+    }
+
+    qualifiedDottedName() {
+        return this.qualifiedName().replace(/[$]/g, '.');
+    }
+
+    validate() {
+        const checkSuperDeclarations = () => {
+            const res = {
+                extends: [],
+                implements: [],
+                first: this.super_declarations[0],
+            };
+            const problems = [];
+            this.super_declarations.forEach((sd) => res[sd.decl_kw.text].push(sd));
+            for (let i = 1; i < res.extends.length; i++) {
+                problems.push(new ParseProblem(res.extends[i].decl_kw, `Types cannot have multiple 'extends' declarations`, ProblemSeverity.Error));
+            }
+            for (let i = 1; i < res.implements.length; i++) {
+                problems.push(new ParseProblem(res.extends[i].decl_kw, `Types cannot have multiple 'implements' declarations`, ProblemSeverity.Error));
+            }
+            if (res.extends.length > 0 && res.implements.length > 0 && res.first.decl_kw.text !== 'extends') {
+                problems.push(new ParseProblem(res.extends[0].decl_kw, `'extends' declaration must appear before 'implements'`, ProblemSeverity.Error));
+            }
+            if (this.kind === 'class' && res.extends.length === 1 && res.extends[0].typelist.length > 1) {
+                problems.push(new ParseProblem(res.extends[0].decl_kw, `Class types cannot extend from multiple super types`, ProblemSeverity.Error));
+            }
+            return problems;
+        };
+        const checkDuplicateFieldNames = () => {
+            // get list of fields, sorted by name
+            const fields = this.declarations
+                .filter((d) => d.kind === 'field')
+                .slice()
+                .sort((a, b) => a.name.text.localeCompare(b.name.text));
+            const probs = [];
+            let name = '';
+            fields.forEach((decl, idx, arr) => {
+                const next = arr[idx + 1];
+                if ((next && decl.name.text === next.name.text) || decl.name.text === name) {
+                    probs.push(new ParseProblem(decl.name, `Duplicate field name: '${decl.name.text}'`, ProblemSeverity.Error));
+                }
+                name = decl.name.text;
+            });
+            return probs;
+        };
+        let problems = [
+            ...ParseProblem.checkDuplicateModifiers(this.modifiers),
+            ...ParseProblem.checkConflictingModifiers(this.modifiers),
+            ...ParseProblem.checkAccessModifiers(this.modifiers, this.kind),
+            ...ParseProblem.checkNonKeywordIdents([this.name]),
+            ...ParseProblem.checkNonKeywordIdents(this.declarations.map((d) => d.name)),
+            ...checkDuplicateFieldNames(),
+            ...checkSuperDeclarations(),
+            ...this.declarations.reduce((probs, d) => {
+                return [...probs, ...d.validate()];
+            }, []),
+        ];
+        return problems;
+    }
+
+    /**
+     * @param {string} package_name 
+     * @param {ResolvedImport[]} imports 
+     * @param {Map<string,*>} typemap 
+     */
+    validateTypes(package_name, imports, typemap) {
+        const problems = [];
+        const fqtypename = package_name ? `${package_name}.${this.qualifiedName()}` : this.qualifiedName();
+
+        /** @type {TypeIdent[]} */
+        let typeidents = [];
+
+        // check extends
+        this.super_declarations.filter(sd => sd.decl_kw.text === 'extends').forEach(sd => {
+            sd.typelist.forEach(typeident => typeidents.push(typeident));
+        })
+        const resolved_extends = resolveTypeIdents(typeidents, package_name, imports, typemap);
+        resolved_extends.forEach((rt,i) => {
+            checkResolvedType(rt, typeidents[i]);
+            if (this.kind === 'class' && rt.mtis.length === 1) {
+                // class extend type must be a class
+                if (rt.mtis[0].typeKind !== 'class') {
+                    problems.push(new ParseProblem(typeidents[i].tokens, `Class '${this.name.text}' cannot extend from ${rt.mtis[0].typeKind} '${rt.label}'; the specified type must be a non-final class.`, ProblemSeverity.Error));
+                }
+                // class extend type cannot be final
+                else if (rt.mtis[0].hasModifier('final')) {
+                    problems.push(new ParseProblem(typeidents[i].tokens, `Class '${this.name.text}' cannot extend from final class '${rt.mtis[0].fullyDottedRawName}'.`, ProblemSeverity.Error));
+                }
+            }
+        });
+
+        // check implements
+        typeidents = [];
+        this.super_declarations.filter(sd => sd.decl_kw.text === 'implements').forEach(sd => {
+            sd.typelist.forEach(typeident => typeidents.push(typeident));
+            if (this.kind !== 'class' && this.kind !== 'enum') {
+                problems.push(new ParseProblem(sd.decl_kw, `implements declarations are not permitted for ${this.kind} types`, ProblemSeverity.Error));
+            }
+        })
+        const resolved_implements = resolveTypeIdents(typeidents, package_name, imports, typemap);
+        resolved_implements.forEach((rt,i) => {
+            checkResolvedType(rt, typeidents[i]);
+            if (/class|enum/.test(this.kind) && rt.mtis.length === 1) {
+                // class implements types must be interfaces
+                if (rt.mtis[0].typeKind !== 'interface') {
+                    problems.push(new ParseProblem(typeidents[i].tokens, `Type '${this.name.text}' cannot implement ${rt.mtis[0].typeKind} type '${rt.mtis[0].fullyDottedRawName}'; the specified type must be an interface.`, ProblemSeverity.Error));
+                }
+                else if (!this.findModifier('abstract')) {
+                    // if the class is not abstract, it must implement all the methods in the interface
+                    // - we can't check this until the MTI for the class is complete
+                    const unimplemented_methods = rt.mtis[0].methods.filter(m => true);
+                    unimplemented_methods.forEach(method => {
+                        problems.push(new ParseProblem(typeidents[i].tokens, `Type '${this.name.text}' is not abstract and does not implement method '${method.toDeclSource()}' declared in interface '${rt.mtis[0].fullyDottedRawName}'.`, ProblemSeverity.Error));
+                    })
+                }
+            }
+        });
+
+        // check field, method-return and parameter types
+        typeidents = [];
+        this.declarations.forEach((d) => {
+            if (d.kind !== 'constructor') {
+                typeidents.push(d.type);
+            }
+            if (d.parameters) {
+                d.parameters.forEach((p) => {
+                    typeidents.push(p.type);
+                });
+            }
+        });
+
+        const resolved_types = resolveTypeIdents(typeidents, fqtypename, imports, typemap);
+        // warn about missing and ambiguous types
+        function checkResolvedType(rt, typeident) {
+            if (rt.error) {
+                problems.push(new ParseProblem(typeident.tokens, rt.error, ProblemSeverity.Error));
+                return;
+            }
+            if (rt.mtis.length === 0) {
+                problems.push(new ParseProblem(typeident.tokens, `Type not found: ${rt.label}`, ProblemSeverity.Error));
+                return;
+            }
+            if (rt.mtis.length > 1) {
+                const names = rt.mtis.map(mti => mti.fullyDottedRawName).join(`' or '`);
+                problems.push(new ParseProblem(typeident.tokens, `Ambiguous type: ${rt.label} - could be '${names}'.`, ProblemSeverity.Error));
+                return;
+            }
+            rt.mtis.forEach(mti => {
+                // void arrays are illegal
+                if (mti.name.startsWith('void[')) {
+                    problems.push(new ParseProblem(typeident.tokens, `primitive void arrays are not a valid type.`, ProblemSeverity.Error));
+                }
+            })
+        }
+        resolved_types.forEach((rt,i) => {
+            checkResolvedType(rt, typeidents[i]);
+
+            // check any type arguments
+            rt.parts.filter(p => p.typeargs).forEach(p => {
+                p.typeargs.forEach(typearg => {
+                    checkResolvedType(typearg, typeidents[i]);
+                    // check type arguments are not primitives (primitive arrays are ok)
+                    if (typearg.mtis.length === 1) {
+                        if (typearg.mtis[0].typeKind === 'primitive') {
+                            problems.push(new ParseProblem(typeidents[i].tokens, `Type arguments cannot be primitive types.`, ProblemSeverity.Error));
+                        }
+                    }
+                })
+            });
+
+        });
+        return problems;
+    }
+}
+
+module.exports = TypeDeclaration;
diff --git a/langserver/java/parsetypes/typeident.js b/langserver/java/parsetypes/typeident.js
new file mode 100644
index 0000000..a24a6de
--- /dev/null
+++ b/langserver/java/parsetypes/typeident.js
@@ -0,0 +1,24 @@
+/**
+ * @typedef {import('./token')} Token
+ * @typedef {import('./resolved-type')} ResolvedType
+ */
+
+/**
+ * Class to represent a declared type in methods, fields, parameters and variables
+ */
+class TypeIdent {
+    /**
+     * @param {Token[]} tokens 
+     */
+    constructor(tokens) {
+        this.tokens = tokens;
+        /** @type {ResolvedType} */
+        this.resolved = null;
+    }
+
+    lastToken() {
+        return this.tokens[this.tokens.length - 1];
+    }
+}
+
+module.exports = TypeIdent;
diff --git a/langserver/java/type-resolver.js b/langserver/java/type-resolver.js
new file mode 100644
index 0000000..0c18ea7
--- /dev/null
+++ b/langserver/java/type-resolver.js
@@ -0,0 +1,264 @@
+const { ResolvedImport } = require('./import-resolver');
+const MTI = require('./mti');
+const ResolvedType = require('./parsetypes/resolved-type');
+
+/**
+ * Parse a type into its various components
+ * @param {string} label 
+ * @returns {{type:ResolvedType, error:string}}
+ */
+function parse_type(label) {
+    const type = new ResolvedType();
+    let re = /([a-zA-Z_]\w*(?:\.[a-zA-Z_]\w*)*)|(\.[a-zA-Z_]\w*)|[<,>]|((?:\[\])+)|( +)|./g;
+    let parts = [type.addTypePart()];
+    for (let m; m = re.exec(label);) {
+        if (m[4]) {
+            // ignore ws
+            continue;
+        }
+        if (!parts[0].name) {
+            if (m[1]) {
+                parts[0].name = m[1];
+                continue;
+            }
+            return { type, error: 'Missing type identifier' };
+        }
+        if (m[0] === '<') {
+            if (!parts[0].typeargs && !parts[0].owner.arrdims) {
+                // start of type arguments - start a new type
+                const t = new ResolvedType();
+                parts[0].typeargs = [t];
+                parts.unshift(t.addTypePart());
+                continue;
+            }
+            return { type, error: `Unexpected '<' character` };
+        }
+        if (m[0] === ',') {
+            if (parts[1] && parts[1].typeargs) {
+                // type argument separator - replace the type on the stack
+                const t = new ResolvedType();
+                parts[1].typeargs.push(t);
+                parts[0] = t.addTypePart();
+                continue;
+            }
+            return { type, error: `Unexpected ',' character` };
+        }
+        if (m[0] === '>') {
+            if (parts[1] && parts[1].typeargs) {
+                // end of type arguments
+                parts.shift();
+                continue;
+            }
+            return { type, error: `Unexpected '>' character` };
+        }
+        if (m[2]) {
+            if (parts[0].typeargs || parts[0].outer) {
+                // post-type-args enclosed type
+                parts[0] = parts[0].inner = parts[0].owner.addTypePart(m[2].slice(1), parts[0]);
+                continue;
+            }
+            return { type, error: `Unexpected '.' character` };
+        }
+        if (m[3]) {
+            parts[0].owner.arrdims = m[3].length / 2;
+            continue;
+        }
+        return { type, error: `Invalid type` };
+    }
+
+    if (parts.length !== 1) {
+        // one or more missing >
+        return { type, error: `Missing >` };
+    }
+
+    return { type, error: '' };
+}
+
+
+/**
+ * Construct a regex to search for an enclosed type in the current and outer scopes of a given type
+ * 
+ * @param {string} fully_qualified_scope the JRE name (a.b.X$Y) of the current type scope
+ * @param {string} dotted_raw_typename the dotted name of the type we are searching for
+ */
+function createTypeScopeRegex(fully_qualified_scope, dotted_raw_typename) {
+    // split the type name across enclosed type boundaries
+    const scopes = fully_qualified_scope.split('$');
+
+    // the first scope is the dotted package name and top-level type - we need to escape the package-qualifier dots for regex
+    scopes[0] = scopes[0].replace(/\./g,'[.]');
+
+    // if the typename we are searching represents an enclosed type, the type-qualifier dots must be replaced with $
+    const enclosed_raw_typename = dotted_raw_typename.replace(/\./g,'[$]');
+
+    // bulld up the list of possible type matches based upon each outer scope of the type
+    const enclosed_type_regexes = [];
+    while (scopes.length) {
+        enclosed_type_regexes.push(`${scopes.join('[$]')}[$]${enclosed_raw_typename}`);
+        scopes.pop();
+    }
+    // the final regex is an exact match of possible type names, sorted from inner scope to outer (top-level) scope
+    return new RegExp(`^(${enclosed_type_regexes.join('|')})$`);
+}
+
+/**
+  * Locate MTIs that match a type.
+  * @param {string} typename The type to resolve
+  * @param {string} fully_qualified_scope The fully-qualified JRE name of the current type scope.
+  * @param {ResolvedImport[]} resolved_imports The list of types resolved from the imports
+  * @param {Map<string,MTI.Type>} typemap the global list of types
+  */
+function resolveType(typename, fully_qualified_scope, resolved_imports, typemap) {
+    const { type, error } = parse_type(typename);
+    if (error) {
+        // don't try to find the type if the parsing failed
+        type.error = error;
+        return type;
+    }
+
+    // locate the MTIs for the type and type arguments
+    resolveCompleteType(type, fully_qualified_scope, resolved_imports, typemap);
+    return type;
+}
+
+/**
+ * 
+ * @param {ResolvedType} type 
+ * @param {string} fully_qualified_scope 
+ * @param {ResolvedImport[]} resolved_imports 
+ * @param {Map<string,MTI.Type>} typemap 
+ */
+function resolveCompleteType(type, fully_qualified_scope, resolved_imports, typemap) {
+
+    type.mtis = findTypeMTIs(type.getDottedRawType(), type.arrdims, fully_qualified_scope, resolved_imports, typemap);
+
+    // resolve type arguments
+    type.parts.filter(p => p.typeargs).forEach(p => {
+        p.typeargs.forEach(typearg => {
+            resolveCompleteType(typearg, fully_qualified_scope, resolved_imports, typemap);
+        })
+    })
+}
+
+
+/**
+ * @param {string} dotted_raw_typename
+ * @param {number} arraydims
+ * @param {string} fully_qualified_scope The fully-qualified JRE name of the current type scope.
+ * @param {ResolvedImport[]} resolved_imports The list of types resolved from the imports
+ * @param {Map<string,MTI.Type>} typemap 
+ */
+function findTypeMTIs(dotted_raw_typename, arraydims, fully_qualified_scope, resolved_imports, typemap) {
+    let mtis = findRawTypeMTIs(dotted_raw_typename, fully_qualified_scope, resolved_imports, typemap);
+
+    if (arraydims > 0) {
+        // convert matches to array MTIs
+        mtis.forEach((mti,idx,arr) => {
+            arr[idx] = MTI.makeArrayType(mti, arraydims);
+        })
+    }
+
+    return mtis;
+}
+
+/**
+ * Match a dotted type name to one or more MTIs
+ * @param {string} dotted_raw_typename
+ * @param {string} fully_qualified_scope The fully-qualified JRE name of the current type scope.
+ * @param {Map<string,MTI.Type>} typemap 
+ * @param {ResolvedImport[]} resolved_imports The list of types resolved from the imports
+ */
+function findRawTypeMTIs(dotted_raw_typename, fully_qualified_scope, resolved_imports, typemap) {
+
+    // first check if it's a simple primitive
+    if (/^(int|char|boolean|void|long|byte|short|float|double)$/.test(dotted_raw_typename)) {
+        // return the primitive type
+        return [MTI.fromPrimitive(dotted_raw_typename)];
+    }
+
+    // create a regex to search for the type name
+    // - the first search is for exact type matches inside the current type scope (and any parent type scopes)
+    let search = createTypeScopeRegex(fully_qualified_scope, dotted_raw_typename); 
+    let matched_types = 
+        resolved_imports.map(ri => ({
+            ri,
+            mtis: ri.fullyQualifiedNames.filter(fqn => search.test(fqn)).map(fqn => ri.types.get(fqn))
+        }))
+        .filter(x => x.mtis.length);
+
+    if (!matched_types.length) {
+        // if the type was not found in the current type scope, construct a new search for the imported types.
+        // - since we don't know if the type name includes package qualifiers or not, this regex allows for implicit
+        //   package prefixes (todo - need to figure out static type imports)
+        search = new RegExp(`^(.+?[.])?${dotted_raw_typename.replace(/\./g,'[.$]')}$`);
+
+        // search the imports for the type
+        matched_types = 
+            resolved_imports.map(ri => ({
+                ri,
+                mtis: ri.fullyQualifiedNames.filter(fqn => search.test(fqn)).map(fqn => ri.types.get(fqn))
+            }))
+            .filter(x => x.mtis.length);
+    }
+
+    // if the type matches multiple import entries, exact imports take prioirity over demand-load imports
+    let exact_import_matches = matched_types.filter(x => x.ri.import && !x.ri.import.asterisk);
+    if (exact_import_matches.length) {
+        if (exact_import_matches.length < matched_types.length) {
+            matched_types = exact_import_matches;
+        }
+    }
+
+    if (!matched_types.length) {
+        // if the type doesn't match any import, the final option is a fully qualified match across all types in all libraries
+        search = new RegExp(`^${dotted_raw_typename.replace(/\./g,'[.$]')}$`);
+        for (let typename of typemap.keys()) {
+            if (search.test(typename)) {
+                matched_types = [{
+                    ri: null,
+                    mtis: [typemap.get(typename)]
+                }];
+                break;
+            }
+        }
+    }
+
+    // at this point, we should (hopefully) have a single matched type
+    // - if the matched_types array is empty, the type is not found
+    // - if the matched_type array has more than one entry, the type matches types across multiple imports
+    // - if the matched_type array has one entry and multiple MTIs, the type matches multiple types in a single import
+    return matched_types.reduce((mtis,mt) => [...mtis, ...mt.mtis] , []);
+}
+
+/**
+ * Converts an array of type name strings to resolved types
+ * @param {string[]} types
+ * @param {string} fully_qualified_scope the JRE name of the type scope we are resolving in
+ * @param {ResolvedImport[]} resolved_imports the list of resolved imports (and types associated with them)
+ * @param {Map<string,MTI.Type>} typemap 
+ */
+function resolveTypes(types, fully_qualified_scope, resolved_imports, typemap) {
+    return types.map(typename => resolveType(typename, fully_qualified_scope, resolved_imports, typemap));
+}
+
+/**
+ * Converts an array of TypeIdent instances to resolved types
+ * @param {import('./parsetypes/typeident')[]} types
+ * @param {string} fully_qualified_scope the JRE name of the type scope we are resolving in
+ * @param {ResolvedImport[]} resolved_imports the list of resolved imports (and types associated with them)
+ * @param {Map<string,MTI.Type>} typemap 
+ */
+function resolveTypeIdents(types, fully_qualified_scope, resolved_imports, typemap) {
+    const names = types.map(typeident => 
+        typeident.tokens.map(token => token.text).join('')
+    );
+    return resolveTypes(names, fully_qualified_scope, resolved_imports, typemap);
+}
+
+
+module.exports = {
+    parse_type,
+    resolveTypes,
+    resolveTypeIdents,
+    ResolvedType,
+}
diff --git a/langserver/server.js b/langserver/server.js
index af54419..9bc7bb2 100644
--- a/langserver/server.js
+++ b/langserver/server.js
@@ -11,327 +11,498 @@ const {
     CompletionItem,
     CompletionItemKind,
     TextDocumentSyncKind,
+    Position,
     //TextDocumentPositionParams
-  } = require('vscode-languageserver');
-  
-  const { TextDocument } = require('vscode-languageserver-textdocument');
+} = require('vscode-languageserver');
 
-  const MTI = require('./java/mti');
-  let androidLibrary = null;
-  function loadAndroidLibrary(retry) {
+const { TextDocument } = require('vscode-languageserver-textdocument');
+
+const MTI = require('./java/mti');
+const { parse, ParseProblem, ProblemSeverity, ParseResult } = require('./java/parser');
+const { resolveImports } = require('./java/import-resolver');
+
+let androidLibrary = null;
+function loadAndroidLibrary(retry) {
     try {
-      androidLibrary = MTI.unpackJSON('/tmp/jarscanner/android-25/android-25.json');
-      connection.console.log(`Android type cache loaded: ${androidLibrary.types.length} types from ${androidLibrary.packages.length} packages.`);
+        androidLibrary = MTI.unpackJSON('/tmp/jarscanner/android-25/android-25.json');
+        connection.console.log(`Android type cache loaded: ${androidLibrary.types.length} types from ${androidLibrary.packages.length} packages.`);
     } catch (e) {
-      connection.console.log(`Failed to load android type cache`);
-      if (retry) {
-        return;
-      }
-      connection.console.log(`Rebuilding type cache...`);
-      const jarscanner = require(`jarscanner/jarscanner`);
-      fs.mkdir('/tmp/jarscanner', err => {
-        if (err) {
-          connection.console.log(`Cannot create type cache folder. ${err.message}.`);
-          return
+        connection.console.log(`Failed to load android type cache`);
+        if (retry) {
+            return;
         }
-        jarscanner.process_android_sdk_source({
-          destpath: '/tmp/jarscanner',
-          sdkpath: process.env['ANDROID_SDK'],
-          api: 25,
-          cleandest: true,
-        }, (err) => {
-          if (err) {
-            connection.console.log(`Android cache build failed. ${err.message}.`);
-            return
-          }
-          loadAndroidLibrary(true);
-        })
-      })
+        connection.console.log(`Rebuilding type cache...`);
+        const jarscanner = require(`jarscanner/jarscanner`);
+        fs.mkdir('/tmp/jarscanner', (err) => {
+            if (err && err.errno !== -17) {
+                connection.console.log(`Cannot create type cache folder. ${err.message}.`);
+                return;
+            }
+            jarscanner.process_android_sdk_source(
+                {
+                    destpath: '/tmp/jarscanner',
+                    sdkpath: process.env['ANDROID_SDK'],
+                    api: 25,
+                    cleandest: true,
+                },
+                (err) => {
+                    if (err) {
+                        connection.console.log(`Android cache build failed. ${err.message}.`);
+                        return;
+                    }
+                    loadAndroidLibrary(true);
+                }
+            );
+        });
     }
-  }
+}
 
-  // Create a connection for the server. The connection uses Node's IPC as a transport.
-  // Also include all preview / proposed LSP features.
-  let connection = createConnection(ProposedFeatures.all);
-  
-  // Create a simple text document manager. The text document manager
-  // supports full document sync only
-  let documents = new TextDocuments({
+// Create a connection for the server. The connection uses Node's IPC as a transport.
+// Also include all preview / proposed LSP features.
+let connection = createConnection(ProposedFeatures.all);
+
+/**
+ * @typedef LiveParseInfo
+ * @property {string} uri
+ * @property {JavaTokenizer.LineInfo[]} lines
+ * @property {{startState: string, states: string[], endState: string}[]} states
+ */
+
+///** @type {LiveParseInfo[]} */
+//const liveParsers = [];
+/** @type {{content: string, uri: string, result: ParseResult, positionAt:(n) => Position, indexAt:(p:Position) => number}} */
+let parsed = null;
+
+function reparse(uri, content) {
+    const result = parse(content);
+    parsed = {
+        content,
+        uri,
+        result,
+        positionAt(n) {
+            let line = 0,
+                last_nl_idx = 0,
+                character = 0;
+            if (n <= 0) return { line, character };
+            for (let idx = 0; ;) {
+                idx = this.content.indexOf('\n', idx) + 1;
+                if (idx === 0 || idx > n) {
+                    if (idx === 0) n = content.length;
+                    character = n - last_nl_idx;
+                    return { line, character };
+                }
+                last_nl_idx = idx;
+                line++;
+            }
+        },
+        indexAt(pos) {
+            let idx = 0;
+            for (let i = 0; i < pos.line; i++) {
+                idx = this.content.indexOf('\n', idx) + 1;
+                if (idx === 0) {
+                    return this.content.length;
+                }
+            }
+            return Math.min(idx + pos.character, this.content.length);
+        },
+    };
+}
+
+// Create a simple text document manager. The text document manager
+// supports full document sync only
+let documents = new TextDocuments({
     /**
-     * 
-     * @param {string} uri 
-     * @param {string} languageId 
-     * @param {number} version 
-     * @param {string} content 
+     *
+     * @param {string} uri
+     * @param {string} languageId
+     * @param {number} version
+     * @param {string} content
      */
     create(uri, languageId, version, content) {
-      connection.console.log(JSON.stringify({what:'create',uri,languageId,version,content}));
+        //connection.console.log(JSON.stringify({what:'create',uri,languageId,version,content}));
+        // tokenize the file content and build the initial parse state
+        connection.console.log(`create parse ${version}`);
+        reparse(uri, content);
+        //connection.console.log(res.imports.length.toString());
+        // const lines = JavaTokenizer.get().tokenizeSource(content);
+        // const initialParse = new JavaParser().parseLines(lines);
+
+        // liveParsers.push({
+        //   uri,
+        //   lines,
+        //   states: initialParse,
+        // })
+        // console.log(initialParse.map(x => x.decls).filter(x => x.length).map(x => JSON.stringify(x, null, '  ')));
+
+        return { uri };
     },
     /**
-     * 
-     * @param {*} document 
-     * @param {import('vscode-languageserver').TextDocumentContentChangeEvent[]} changes 
-     * @param {number} version 
+     *
+     * @param {TextDocument} document
+     * @param {import('vscode-languageserver').TextDocumentContentChangeEvent[]} changes
+     * @param {number} version
      */
     update(document, changes, version) {
-      connection.console.log(JSON.stringify({what:'update',changes,version}));
-    }
+        connection.console.log(JSON.stringify({ what: 'update', changes, version }));
+        //connection.console.log(`update ${version}`);
+        //return document;
+        if (parsed && document && parsed.uri === document.uri) {
+            changes.forEach((change) => {
+                /** @type {import('vscode-languageserver').Range} */
+                const r = change['range'];
+                if (r) {
+                    const start_index = parsed.indexAt(r.start);
+                    let end_index = start_index + (r.end.character - r.start.character);
+                    if (r.end.line !== r.start.line) end_index = parsed.indexAt(r.end);
+                    parsed.content = `${parsed.content.slice(0, start_index)}${change.text}${parsed.content.slice(end_index)}`;
+                }
+            });
+            //connection.console.log(JSON.stringify(parsed.content));
+            reparse(document.uri, parsed.content);
+        }
+        return document;
+    },
+});
 
-  });
-  
-  let hasConfigurationCapability = false;
-  let hasWorkspaceFolderCapability = false;
-  let hasDiagnosticRelatedInformationCapability = false;
-  
-  connection.onInitialize((params) => {
+let hasConfigurationCapability = false;
+let hasWorkspaceFolderCapability = false;
+let hasDiagnosticRelatedInformationCapability = false;
+
+connection.onInitialize((params) => {
     process.nextTick(loadAndroidLibrary);
     let capabilities = params.capabilities;
-  
+
     // Does the client support the `workspace/configuration` request?
     // If not, we will fall back using global settings
-    hasConfigurationCapability =
-      capabilities.workspace && !!capabilities.workspace.configuration;
+    hasConfigurationCapability = capabilities.workspace && !!capabilities.workspace.configuration;
 
-    hasWorkspaceFolderCapability =
-      capabilities.workspace && !!capabilities.workspace.workspaceFolders;
+    hasWorkspaceFolderCapability = capabilities.workspace && !!capabilities.workspace.workspaceFolders;
 
     hasDiagnosticRelatedInformationCapability =
-      capabilities.textDocument &&
-      capabilities.textDocument.publishDiagnostics &&
-      capabilities.textDocument.publishDiagnostics.relatedInformation;
-  
+        capabilities.textDocument && capabilities.textDocument.publishDiagnostics && capabilities.textDocument.publishDiagnostics.relatedInformation;
+
     return {
-      capabilities: {
-        textDocumentSync: TextDocumentSyncKind.Incremental,
-        // Tell the client that the server supports code completion
-        completionProvider: {
-          resolveProvider: true
-        }
-      }
+        capabilities: {
+            textDocumentSync: TextDocumentSyncKind.Incremental,
+            // Tell the client that the server supports code completion
+            completionProvider: {
+                resolveProvider: true,
+            },
+        },
     };
-  });
-  
-  connection.onInitialized(() => {
+});
+
+connection.onInitialized(() => {
     if (hasConfigurationCapability) {
-      // Register for all configuration changes.
-      connection.client.register(DidChangeConfigurationNotification.type, undefined);
+        // Register for all configuration changes.
+        connection.client.register(DidChangeConfigurationNotification.type, undefined);
     }
     if (hasWorkspaceFolderCapability) {
-      connection.workspace.onDidChangeWorkspaceFolders(_event => {
-        connection.console.log('Workspace folder change event received.');
-      });
+        connection.workspace.onDidChangeWorkspaceFolders((_event) => {
+            connection.console.log('Workspace folder change event received.');
+        });
     }
-  });
-  
-  // The example settings
-  /**
-   * @typedef ExampleSettings
-   * @property {number} maxNumberOfProblems
-   */
-  
-  // The global settings, used when the `workspace/configuration` request is not supported by the client.
-  // Please note that this is not the case when using this server with the client provided in this example
-  // but could happen with other clients.
-  const defaultSettings = { maxNumberOfProblems: 1000 };
-  let globalSettings = defaultSettings;
-  
-  // Cache the settings of all open documents
-  /** @type {Map<string, Thenable<ExampleSettings>>} */
-  let documentSettings = new Map();
-  
-  connection.onDidChangeConfiguration(change => {
+});
+
+// The example settings
+/**
+ * @typedef ExampleSettings
+ * @property {number} maxNumberOfProblems
+ */
+
+// The global settings, used when the `workspace/configuration` request is not supported by the client.
+// Please note that this is not the case when using this server with the client provided in this example
+// but could happen with other clients.
+const defaultSettings = { maxNumberOfProblems: 1000 };
+let globalSettings = defaultSettings;
+
+// Cache the settings of all open documents
+/** @type {Map<string, Thenable<ExampleSettings>>} */
+let documentSettings = new Map();
+
+connection.onDidChangeConfiguration((change) => {
     if (hasConfigurationCapability) {
-      // Reset all cached document settings
-      documentSettings.clear();
+        // Reset all cached document settings
+        documentSettings.clear();
     } else {
-      globalSettings = (
-        (change.settings.androidJavaLanguageServer || defaultSettings)
-      );
+        globalSettings = change.settings.androidJavaLanguageServer || defaultSettings;
     }
-  
+
     // Revalidate all open text documents
     documents.all().forEach(validateTextDocument);
-  });
-  
-  function getDocumentSettings(resource) {
+});
+
+function getDocumentSettings(resource) {
     if (!hasConfigurationCapability) {
-      return Promise.resolve(globalSettings);
+        return Promise.resolve(globalSettings);
     }
     let result = documentSettings.get(resource);
     if (!result) {
-      result = connection.workspace.getConfiguration({
-        scopeUri: resource,
-        section: 'androidJavaLanguageServer'
-      });
-      documentSettings.set(resource, result);
+        result = connection.workspace.getConfiguration({
+            scopeUri: resource,
+            section: 'androidJavaLanguageServer',
+        });
+        documentSettings.set(resource, result);
     }
     return result;
-  }
-  
-  // Only keep settings for open documents
-  documents.onDidClose(e => {
+}
+
+// Only keep settings for open documents
+documents.onDidClose((e) => {
+    connection.console.log('doc closed');
+    parsed = null;
     documentSettings.delete(e.document.uri);
-  });
-  
-  // The content of a text document has changed. This event is emitted
-  // when the text document first opened or when its content has changed.
-  // documents.onDidChangeContent(change => {
-  //   connection.console.log(JSON.stringify(change));
-    //validateTextDocument(change.document);
-  // });
-  
-  /**
-   * @param {TextDocument} textDocument 
-   */
-  async function validateTextDocument(textDocument) {
+});
+
+// The content of a text document has changed. This event is emitted
+// when the text document first opened or when its content has changed.
+documents.onDidChangeContent((change) => {
+    connection.console.log(JSON.stringify(change));
+    validateTextDocument(change.document);
+});
+
+/**
+ * @param {{uri}} textDocument
+ */
+async function validateTextDocument(textDocument) {
+    /** @type {ParseProblem[]} */
+    let problems = [];
+    connection.console.log('validateTextDocument');
+
+    if (parsed && parsed.result) {
+        // package problem
+        if (parsed.result.package) {
+            problems = [...problems, ...parsed.result.package.validate()];
+        }
+
+        // import problems
+        problems = parsed.result.imports.reduce((problems, import_decl) => {
+            return [...problems, ...import_decl.validate()];
+        }, problems);
+
+        // type problems
+        problems = parsed.result.types.reduce((problems, type_decl) => {
+            return [...problems, ...type_decl.validate()];
+        }, problems);
+
+        // syntax problems
+        problems = parsed.result.invalids.reduce((problems, invalid) => {
+            return [...problems, ...invalid.validate()];
+        }, problems);
+
+        const package_name = parsed.result.package ? parsed.result.package.dottedName() : '';
+        const source_mtis = parsed.result.types.map(type_decl => {
+            return new MTI().addType(package_name, type_decl.getDocString(), type_decl.getAccessModifierValues(), type_decl.kind, type_decl.qualifiedName());
+        })
+        const imports = resolveImports(androidLibrary, parsed.result.imports, package_name, source_mtis);
+
+        // missing/invalid imports
+        problems = imports.unresolved.reduce((problems, unresolved) => {
+            const fqn = unresolved.nameparts.join('.');
+            return [...problems, new ParseProblem(unresolved.nameparts, `Unresolved import: ${fqn}`, ProblemSeverity.Warning)];
+        }, problems);
+
+        // resolved types
+        problems = parsed.result.types.reduce((problems, type_decl) => {
+            return [...problems, ...type_decl.validateTypes(package_name, imports.resolved, imports.typemap)];
+        }, problems);
+
+        // duplicate type names
+        /** @type {Map<string,import('./java/parsetypes/type')[]>} */
+        const typenames = new Map();
+        parsed.result.types.forEach(type_decl => {
+            const qname = type_decl.qualifiedName();
+            let list = typenames.get(qname);
+            if (!list) typenames.set(qname, list = []);
+            list.push(type_decl);
+        });
+        [...typenames.values()]
+            .filter(list => list.length > 1)
+            .forEach(list => {
+                problems = [...problems, ...list.map(type_decl => new ParseProblem(type_decl.name, `Duplicate type: ${type_decl.qualifiedDottedName()}`, ProblemSeverity.Error))];
+            });
+    }
+
+    const diagnostics = problems
+        .filter((p) => p)
+        .map((p) => {
+            const start = parsed.positionAt(p.startIdx);
+            const end = parsed.positionAt(p.endIdx);
+            /** @type {Diagnostic} */
+            let diagnostic = {
+                severity: p.severity,
+                range: {
+                    start,
+                    end,
+                },
+                message: p.message,
+                source: 'java-android',
+            };
+            return diagnostic;
+        });
+    connection.sendDiagnostics({ uri: textDocument.uri, diagnostics });
+}
+
+async function validateTextDocument2(textDocument) {
     // In this simple example we get the settings for every validate run.
     //let settings = await getDocumentSettings(textDocument.uri);
-  
+
     // The validator creates diagnostics for all uppercase words length 2 and more
     let text = textDocument.getText();
     let pattern = /\b[A-Z]{2,}\b/g;
     let m;
-  
+
     let problems = 0;
     let diagnostics = [];
     while ((m = pattern.exec(text)) /* && problems < settings.maxNumberOfProblems */) {
-      problems++;
-      /** @type {Diagnostic} */
-      let diagnostic = {
-        severity: DiagnosticSeverity.Warning,
-        range: {
-          start: textDocument.positionAt(m.index),
-          end: textDocument.positionAt(m.index + m[0].length)
-        },
-        message: `${m[0]} is all uppercase.`,
-        source: 'ex'
-      };
-      if (hasDiagnosticRelatedInformationCapability) {
-        diagnostic.relatedInformation = [
-          {
-            location: {
-              uri: textDocument.uri,
-              range: Object.assign({}, diagnostic.range)
+        problems++;
+        /** @type {Diagnostic} */
+        let diagnostic = {
+            severity: DiagnosticSeverity.Warning,
+            range: {
+                start: textDocument.positionAt(m.index),
+                end: textDocument.positionAt(m.index + m[0].length),
             },
-            message: 'Spelling matters'
-          },
-          {
-            location: {
-              uri: textDocument.uri,
-              range: Object.assign({}, diagnostic.range)
-            },
-            message: 'Particularly for names'
-          }
-        ];
-      }
-      diagnostics.push(diagnostic);
+            message: `${m[0]} is all uppercase.`,
+            source: 'ex',
+        };
+        if (hasDiagnosticRelatedInformationCapability) {
+            diagnostic.relatedInformation = [
+                {
+                    location: {
+                        uri: textDocument.uri,
+                        range: Object.assign({}, diagnostic.range),
+                    },
+                    message: 'Spelling matters',
+                },
+                {
+                    location: {
+                        uri: textDocument.uri,
+                        range: Object.assign({}, diagnostic.range),
+                    },
+                    message: 'Particularly for names',
+                },
+            ];
+        }
+        diagnostics.push(diagnostic);
     }
-  
+
     // Send the computed diagnostics to VS Code.
     connection.sendDiagnostics({ uri: textDocument.uri, diagnostics });
-  }
-  
-  connection.onDidChangeWatchedFiles(_change => {
+}
+
+connection.onDidChangeWatchedFiles((_change) => {
     // Monitored files have change in VS Code
     connection.console.log('We received a file change event');
-  });
-  
-  // This handler provides the initial list of the completion items.
-  let allCompletionTypes = null;
-  connection.onCompletion(
-      /**
-       * @param {*} _textDocumentPosition TextDocumentPositionParams
-       */
+});
+
+// This handler provides the initial list of the completion items.
+let allCompletionTypes = null;
+connection.onCompletion(
+    /**
+     * @param {*} _textDocumentPosition TextDocumentPositionParams
+     */
     (_textDocumentPosition) => {
-      // The pass parameter contains the position of the text document in
-      // which code complete got requested. For the example we ignore this
-      // info and always provide the same completion items.
-      const lib = androidLibrary;
-      if (!lib) return [];
-      const typeKindMap = {
-          'class':CompletionItemKind.Class,
-          'interface': CompletionItemKind.Interface,
-          '@interface': CompletionItemKind.Interface,
-          'enum': CompletionItemKind.Enum,
+        // The pass parameter contains the position of the text document in
+        // which code complete got requested. For the example we ignore this
+        // info and always provide the same completion items.
+        const lib = androidLibrary;
+        if (!lib) return [];
+        const typeKindMap = {
+            class: CompletionItemKind.Class,
+            interface: CompletionItemKind.Interface,
+            '@interface': CompletionItemKind.Interface,
+            enum: CompletionItemKind.Enum,
         };
-      return allCompletionTypes || (allCompletionTypes = lib.types.map((t,idx) =>
-          /** @type {CompletionItem} */
-        ({
-            label: t.dottedRawName,
-            kind: typeKindMap[t.typeKind],
-            data: idx
-          })
-      ));
-      return [
-        {
-          label: 'TypeScript',
-          kind: CompletionItemKind.Text,
-          data: 1
-        },
-        {
-          label: 'JavaScript',
-          kind: CompletionItemKind.Text,
-          data: 2
-        }
-      ];
+        return (
+            allCompletionTypes ||
+            (allCompletionTypes = [
+                ...'boolean byte char double float int long short void'.split(' ').map((t) => ({
+                    label: t,
+                    kind: CompletionItemKind.Keyword,
+                    data: -1,
+                })),
+                ...'public private protected static final abstract volatile native'.split(' ').map((t) => ({
+                    label: t,
+                    kind: CompletionItemKind.Keyword,
+                    data: -1,
+                })),
+                ...'false true null'.split(' ').map((t) => ({
+                    label: t,
+                    kind: CompletionItemKind.Value,
+                    data: -1,
+                })),
+                ...lib.types.map(
+                    (t, idx) =>
+                        /** @type {CompletionItem} */
+                        ({
+                            label: t.dottedRawName,
+                            kind: typeKindMap[t.typeKind],
+                            data: idx,
+                        })
+                ),
+            ])
+        );
     }
-  );
-  
-  // This handler resolves additional information for the item selected in
-  // the completion list.
-  connection.onCompletionResolve(
+);
+
+// This handler resolves additional information for the item selected in
+// the completion list.
+connection.onCompletionResolve(
     /**
      * @param {CompletionItem} item
      */
     (item) => {
-       const t = androidLibrary.types[item.data];
-      item.detail = `${t.package}.${t.dottedRawName}`;
-      item.documentation = t.docs && {
-          kind: "markdown",
-          value: `${t.typeKind} **${t.dottedName}**\n\n${
-              t.docs
-              .replace(/(<p ?.*?>)|(<\/?i>|<\/?em>)|(<\/?b>|<\/?strong>|<\/?dt>)|(<\/?tt>)|(<\/?code>|<\/?pre>)|(\{@link.+?\}|\{@code.+?\})|(<li>)|(<a href="\{@docRoot\}.*?">.+?<\/a>)|(<h\d>)|<\/?dd ?.*?>|<\/p ?.*?>|<\/h\d ?.*?>|<\/?div ?.*?>|<\/?[uo]l ?.*?>/gim, (_,p,i,b,tt,c,lc,li,a,h) => {
-                  return p ? '\n\n' 
-                  : i ? '*' 
-                  : b ? '**' 
-                  : tt ? '`'
-                  : c ? '\n```'
-                  : lc ? lc.replace(/\{@\w+\s*(.+)\}/, (_,x) => `\`${x.trim()}\``)
-                  : li ? '\n- '
-                  : a ? a.replace(/.+?\{@docRoot\}(.*?)">(.+?)<\/a>/m, (_,p,t) => `[${t}](https://developer.android.com/${p})`)
-                  : h ? `\n${'#'.repeat(1 + parseInt(h.slice(2,-1),10))} `
-                  : '';
-              })
+        const t = androidLibrary.types[item.data];
+        if (!t) {
+            return item;
+        }
+        item.detail = `${t.package}.${t.dottedRawName}`;
+        item.documentation = t.docs && {
+            kind: 'markdown',
+            value: `${t.typeKind} **${t.dottedName}**\n\n${
+                t.docs
+                .replace(/(<p ?.*?>)|(<\/?i>|<\/?em>)|(<\/?b>|<\/?strong>|<\/?dt>)|(<\/?tt>)|(<\/?code>|<\/?pre>)|(\{@link.+?\}|\{@code.+?\})|(<li>)|(<a href="\{@docRoot\}.*?">.+?<\/a>)|(<h\d>)|<\/?dd ?.*?>|<\/p ?.*?>|<\/h\d ?.*?>|<\/?div ?.*?>|<\/?[uo]l ?.*?>/gim, (_,p,i,b,tt,c,lc,li,a,h) => {
+                    return p ? '\n\n' 
+                    : i ? '*' 
+                    : b ? '**' 
+                    : tt ? '`'
+                    : c ? '\n```'
+                    : lc ? lc.replace(/\{@\w+\s*(.+)\}/, (_,x) => `\`${x.trim()}\``)
+                    : li ? '\n- '
+                    : a ? a.replace(/.+?\{@docRoot\}(.*?)">(.+?)<\/a>/m, (_,p,t) => `[${t}](https://developer.android.com/${p})`)
+                    : h ? `\n${'#'.repeat(1 + parseInt(h.slice(2,-1),10))} `
+                    : '';
+                })
             }`,
-      }
-      return item;
+        };
+        return item;
     }
-  );
-  
-  /*
-  connection.onDidOpenTextDocument((params) => {
-      // A text document got opened in VS Code.
-      // params.uri uniquely identifies the document. For documents store on disk this is a file URI.
-      // params.text the initial full content of the document.
-      connection.console.log(`${params.textDocument.uri} opened.`);
-  });
-  connection.onDidChangeTextDocument((params) => {
-      // The content of a text document did change in VS Code.
-      // params.uri uniquely identifies the document.
-      // params.contentChanges describe the content changes to the document.
-      connection.console.log(`${params.textDocument.uri} changed: ${JSON.stringify(params.contentChanges)}`);
-  });
-  connection.onDidCloseTextDocument((params) => {
-      // A text document got closed in VS Code.
-      // params.uri uniquely identifies the document.
-      connection.console.log(`${params.textDocument.uri} closed.`);
-  });
-  */
-  
-  // Make the text document manager listen on the connection
-  // for open, change and close text document events
-  documents.listen(connection);
-  
-  // Listen on the connection
-  connection.listen();
-  
\ No newline at end of file
+);
+
+/*
+    connection.onDidOpenTextDocument((params) => {
+        // A text document got opened in VS Code.
+        // params.uri uniquely identifies the document. For documents store on disk this is a file URI.
+        // params.text the initial full content of the document.
+        connection.console.log(`${params.textDocument.uri} opened.`);
+    });
+    connection.onDidChangeTextDocument((params) => {
+        // The content of a text document did change in VS Code.
+        // params.uri uniquely identifies the document.
+        // params.contentChanges describe the content changes to the document.
+        connection.console.log(`${params.textDocument.uri} changed: ${JSON.stringify(params.contentChanges)}`);
+    });
+    connection.onDidCloseTextDocument((params) => {
+        // A text document got closed in VS Code.
+        // params.uri uniquely identifies the document.
+        connection.console.log(`${params.textDocument.uri} closed.`);
+    });
+    */
+
+// Make the text document manager listen on the connection
+// for open, change and close text document events
+documents.listen(connection);
+
+// Listen on the connection
+connection.listen();