Java bindings with no finalizers

Replacing finalizers with PhantomReferences, required quite a lot of
changes to the codebase.

src/api/java/AST.java

@@ -187,34 +187,15 @@ public class AST extends Z3Object implements Comparable<AST>
         return Native.astToString(getContext().nCtx(), getNativeObject());
     }
 
-    AST(Context ctx)
+    AST(Context ctx, long obj) {
-    {
-        super(ctx);
-    }
-
-    AST(Context ctx, long obj)
-    {
         super(ctx, obj);
     }
 
     @Override
     void incRef(long o)
     {
-        // Console.WriteLine("AST IncRef()");
+        Native.incRef(getContext().nCtx(), o);
-        if (getContext() == null || o == 0)
+        getContext().getASTDRQ().storeReference(getContext(), this);
-            return;
-        getContext().getASTDRQ().incAndClear(getContext(), o);
-        super.incRef(o);
-    }
-
-    @Override
-    void decRef(long o)
-    {
-        // Console.WriteLine("AST DecRef()");
-        if (getContext() == null || o == 0)
-            return;
-        getContext().getASTDRQ().add(o);
-        super.decRef(o);
     }
 
     static AST create(Context ctx, long obj)

src/api/java/ASTDecRefQueue.java

@@ -17,7 +17,7 @@ Notes:
 
 package com.microsoft.z3;
 
-class ASTDecRefQueue extends IDecRefQueue
+class ASTDecRefQueue extends IDecRefQueue<AST>
 {
     public ASTDecRefQueue() 
     {
@@ -30,26 +30,7 @@ class ASTDecRefQueue extends IDecRefQueue
     }
 
     @Override
-    protected void incRef(Context ctx, long obj)
+    protected void decRef(Context ctx, long obj) {
-    {
-        try
-        {
-            Native.incRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
-    }
-
-    @Override
-    protected void decRef(Context ctx, long obj)
-    {
-        try
-        {
         Native.decRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
     }
 };

src/api/java/ASTMap.java

@@ -120,14 +120,7 @@ class ASTMap extends Z3Object
     @Override
     void incRef(long o)
     {
-        getContext().getASTMapDRQ().incAndClear(getContext(), o);
+        Native.astMapIncRef(getContext().nCtx(), o);
-        super.incRef(o);
+        getContext().getASTMapDRQ().storeReference(getContext(), this);
-    }
-
-    @Override
-    void decRef(long o)
-    {
-        getContext().getASTMapDRQ().add(o);
-        super.decRef(o);
     }
 }

src/api/java/ASTVector.java

@@ -105,15 +105,8 @@ public class ASTVector extends Z3Object
     @Override
     void incRef(long o)
     {
-        getContext().getASTVectorDRQ().incAndClear(getContext(), o);
+        Native.astVectorIncRef(getContext().nCtx(), o);
-        super.incRef(o);
+        getContext().getASTVectorDRQ().storeReference(getContext(), this);
-    }
-
-    @Override
-    void decRef(long o)
-    {
-        getContext().getASTVectorDRQ().add(o);
-        super.decRef(o);
     }
 
     /**

src/api/java/ApplyResult.java

@@ -74,16 +74,8 @@ public class ApplyResult extends Z3Object
     }
 
     @Override
-    void incRef(long o)
+    void incRef(long o) {
-    {
+        Native.applyResultIncRef(getContext().nCtx(), o);
-        getContext().getApplyResultDRQ().incAndClear(getContext(), o);
+        getContext().getApplyResultDRQ().storeReference(getContext(), this);
-        super.incRef(o);
-    }
-
-    @Override
-    void decRef(long o)
-    {
-        getContext().getApplyResultDRQ().add(o);
-        super.decRef(o);
     }
 }

src/api/java/ApplyResultDecRefQueue.java

@@ -17,7 +17,7 @@ Notes:
 
 package com.microsoft.z3;
 
-class ApplyResultDecRefQueue extends IDecRefQueue
+class ApplyResultDecRefQueue extends IDecRefQueue<ApplyResult>
 {
     public ApplyResultDecRefQueue() 
     {
@@ -30,26 +30,7 @@ class ApplyResultDecRefQueue extends IDecRefQueue
     }
 
     @Override
-    protected void incRef(Context ctx, long obj)
+    protected void decRef(Context ctx, long obj) {
-    {
-        try
-        {
-            Native.applyResultIncRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
-    }
-
-    @Override
-    protected void decRef(Context ctx, long obj)
-    {
-        try
-        {
         Native.applyResultDecRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
     }
 };

src/api/java/AstMapDecRefQueue.java

@@ -17,7 +17,7 @@ Notes:
 
 package com.microsoft.z3;
 
-class ASTMapDecRefQueue extends IDecRefQueue
+class ASTMapDecRefQueue extends IDecRefQueue<ASTMap>
 {
     public ASTMapDecRefQueue() 
     {
@@ -30,26 +30,7 @@ class ASTMapDecRefQueue extends IDecRefQueue
     }
 
     @Override
-    protected void incRef(Context ctx, long obj)
+    protected void decRef(Context ctx, long obj) {
-    {
-        try
-        {
-            Native.astMapIncRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
-    }
-
-    @Override
-    protected void decRef(Context ctx, long obj)
-    {
-        try
-        {
         Native.astMapDecRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
     }
 };

src/api/java/AstVectorDecRefQueue.java

@@ -17,7 +17,7 @@ Notes:
 
 package com.microsoft.z3;
 
-class ASTVectorDecRefQueue extends IDecRefQueue
+class ASTVectorDecRefQueue extends IDecRefQueue<ASTVector>
 {
     public ASTVectorDecRefQueue() 
     {
@@ -30,26 +30,7 @@ class ASTVectorDecRefQueue extends IDecRefQueue
     }
 
     @Override
-    protected void incRef(Context ctx, long obj)
+    protected void decRef(Context ctx, long obj) {
-    {
-        try
-        {
-            Native.astVectorIncRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
-    }
-
-    @Override
-    protected void decRef(Context ctx, long obj)
-    {
-        try
-        {
         Native.astVectorDecRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
     }
 };

src/api/java/BoolExpr.java

@@ -20,15 +20,7 @@ package com.microsoft.z3;
 /**
  * Boolean expressions
  **/
-public class BoolExpr extends Expr
+public class BoolExpr extends Expr {
-{
-    /**
-     * Constructor for BoolExpr
-     **/
-    protected BoolExpr(Context ctx)
-    {
-        super(ctx);
-    }
 
     /**
      * Constructor for BoolExpr

src/api/java/Constructor.java

@@ -20,8 +20,14 @@ package com.microsoft.z3;
 /**
  * Constructors are used for datatype sorts.
  **/
-public class Constructor extends Z3Object
+public class Constructor extends Z3Object {
-{
+    private final int n;
+
+    Constructor(Context ctx, int n, long nativeObj) {
+        super(ctx, nativeObj);
+        this.n = n;
+    }
+
     /**
      * The number of fields of the constructor.
      * @throws Z3Exception 
@@ -78,29 +84,16 @@ public class Constructor extends Z3Object
         return t;
     }
 
-    /**
+    @Override
-     * Destructor.
+    void incRef(long o) {
-     * @throws Throwable 
+
-     * @throws Z3Exception on error
+        // Datatype constructors are not reference counted.
-     **/
+        getContext().getConstructorDRQ().storeReference(getContext(), this);
-    protected void finalize() throws Throwable
-    {
-        try {
-            Native.delConstructor(getContext().nCtx(), getNativeObject());
-        } finally {
-            super.finalize();
-        }
     }
 
-    private int n = 0;
+    static Constructor of(Context ctx, Symbol name, Symbol recognizer,
-
+            Symbol[] fieldNames, Sort[] sorts, int[] sortRefs) {
-    Constructor(Context ctx, Symbol name, Symbol recognizer,
+        int n = AST.arrayLength(fieldNames);
-            Symbol[] fieldNames, Sort[] sorts, int[] sortRefs)
-           
-    {
-        super(ctx);
-
-        n = AST.arrayLength(fieldNames);
 
         if (n != AST.arrayLength(sorts))
             throw new Z3Exception(
@@ -112,9 +105,10 @@ public class Constructor extends Z3Object
         if (sortRefs == null)
             sortRefs = new int[n];
 
-        setNativeObject(Native.mkConstructor(ctx.nCtx(), name.getNativeObject(),
+        long nativeObj = Native.mkConstructor(ctx.nCtx(), name.getNativeObject(),
                 recognizer.getNativeObject(), n, Symbol.arrayToNative(fieldNames),
-                Sort.arrayToNative(sorts), sortRefs));
+                Sort.arrayToNative(sorts), sortRefs);
+        return new Constructor(ctx, n, nativeObj);
 
     }
 }

src/api/java/ConstructorList.java

@@ -20,32 +20,21 @@ package com.microsoft.z3;
 /**
  * Lists of constructors
  **/
-public class ConstructorList extends Z3Object
+public class ConstructorList extends Z3Object {
-{
-    /**
-     * Destructor.
-     * @throws Throwable 
-     * @throws Z3Exception on error
-     **/
-    protected void finalize() throws Throwable
-    {
-        try {        
-            Native.delConstructorList(getContext().nCtx(), getNativeObject());            
-        } finally {
-            super.finalize();
-        }
-    }
 
     ConstructorList(Context ctx, long obj)
     {
         super(ctx, obj);
     }
 
+    @Override
+    void incRef(long o) {
+        getContext().getConstructorListDRQ().storeReference(getContext(), this);
+    }
+
     ConstructorList(Context ctx, Constructor[] constructors)
     {
-        super(ctx);
+        super(ctx, Native.mkConstructorList(ctx.nCtx(),
-
-        setNativeObject(Native.mkConstructorList(getContext().nCtx(),
                 constructors.length,
                 Constructor.arrayToNative(constructors)));
     }

src/api/java/Context.java

@@ -17,28 +17,29 @@ Notes:
 
 package com.microsoft.z3;
 
-import java.util.Map;
+import static com.microsoft.z3.Constructor.of;
-import java.util.concurrent.atomic.AtomicInteger;
 
 import com.microsoft.z3.enumerations.Z3_ast_print_mode;
 
+import java.util.Map;
+
 /**
  * The main interaction with Z3 happens via the Context.
  **/
-public class Context extends IDisposable
+public class Context implements AutoCloseable {
-{
+    private final long m_ctx;
-    /**
+    static final Object creation_lock = new Object();
-     * Constructor.
+
-     **/
+    public static Context mkContext() {
-    public Context()
+        long m_ctx;
-    {        
-        super();
         synchronized (creation_lock) {
             m_ctx = Native.mkContextRc(0);
-            initContext();
+            // TODO: then adding settings will not be under the lock.
         }
+        return new Context(m_ctx);
     }
 
+
     /**
      * Constructor.
      * Remarks:
@@ -56,17 +57,29 @@ public class Context extends IDisposable
      * Note that in previous versions of Z3, this constructor was also used to set global and
      * module parameters. For this purpose we should now use {@code Global.setParameter}
      **/
-    public Context(Map<String, String> settings)
+    public static Context mkContext(Map<String, String> settings)
     {
-        super();
+        long m_ctx;
         synchronized (creation_lock) {
             long cfg = Native.mkConfig();
             for (Map.Entry<String, String> kv : settings.entrySet())
                 Native.setParamValue(cfg, kv.getKey(), kv.getValue());
             m_ctx = Native.mkContextRc(cfg);
             Native.delConfig(cfg);
-            initContext();
         }
+        return new Context(m_ctx);
+    }
+
+    /**
+     * Constructor.
+     **/
+    protected Context(long m_ctx)
+    {
+        this.m_ctx = m_ctx;
+
+        // Code which used to be in "initContext".
+        setPrintMode(Z3_ast_print_mode.Z3_PRINT_SMTLIB2_COMPLIANT);
+        Native.setInternalErrorHandler(m_ctx);
     }
 
     /**
@@ -242,7 +255,7 @@ public class Context extends IDisposable
         checkContextMatch(name);
         checkContextMatch(fieldNames);
         checkContextMatch(fieldSorts);
-        return new TupleSort(this, name, (int) fieldNames.length, fieldNames,
+        return new TupleSort(this, name, fieldNames.length, fieldNames,
                 fieldSorts);
     }
 
@@ -319,8 +332,7 @@ public class Context extends IDisposable
             Symbol[] fieldNames, Sort[] sorts, int[] sortRefs)
            
     {
-
+        return of(this, name, recognizer, fieldNames, sorts,
-        return new Constructor(this, name, recognizer, fieldNames, sorts,
                 sortRefs);
     }
 
@@ -329,10 +341,8 @@ public class Context extends IDisposable
      **/
     public Constructor mkConstructor(String name, String recognizer,
             String[] fieldNames, Sort[] sorts, int[] sortRefs)
-           
     {
-
+        return of(this, mkSymbol(name), mkSymbol(recognizer),
-        return new Constructor(this, mkSymbol(name), mkSymbol(recognizer),
                 mkSymbols(fieldNames), sorts, sortRefs);
     }
 
@@ -525,7 +535,7 @@ public class Context extends IDisposable
             throw new Z3Exception("Cannot create a pattern from zero terms");
 
         long[] termsNative = AST.arrayToNative(terms);
-        return new Pattern(this, Native.mkPattern(nCtx(), (int) terms.length,
+        return new Pattern(this, Native.mkPattern(nCtx(), terms.length,
                 termsNative));
     }
 
@@ -688,7 +698,7 @@ public class Context extends IDisposable
     public BoolExpr mkDistinct(Expr... args)
     {
         checkContextMatch(args);
-        return new BoolExpr(this, Native.mkDistinct(nCtx(), (int) args.length,
+        return new BoolExpr(this, Native.mkDistinct(nCtx(), args.length,
                 AST.arrayToNative(args)));
     }
 
@@ -756,7 +766,7 @@ public class Context extends IDisposable
     public BoolExpr mkAnd(BoolExpr... t)
     {
         checkContextMatch(t);
-        return new BoolExpr(this, Native.mkAnd(nCtx(), (int) t.length,
+        return new BoolExpr(this, Native.mkAnd(nCtx(), t.length,
                 AST.arrayToNative(t)));
     }
 
@@ -766,7 +776,7 @@ public class Context extends IDisposable
     public BoolExpr mkOr(BoolExpr... t)
     {
         checkContextMatch(t);
-        return new BoolExpr(this, Native.mkOr(nCtx(), (int) t.length,
+        return new BoolExpr(this, Native.mkOr(nCtx(), t.length,
                 AST.arrayToNative(t)));
     }
 
@@ -777,7 +787,7 @@ public class Context extends IDisposable
     {
         checkContextMatch(t);
         return (ArithExpr) Expr.create(this,
-                Native.mkAdd(nCtx(), (int) t.length, AST.arrayToNative(t)));
+                Native.mkAdd(nCtx(), t.length, AST.arrayToNative(t)));
     }
 
     /**
@@ -787,7 +797,7 @@ public class Context extends IDisposable
     {
         checkContextMatch(t);
         return (ArithExpr) Expr.create(this,
-                Native.mkMul(nCtx(), (int) t.length, AST.arrayToNative(t)));
+                Native.mkMul(nCtx(), t.length, AST.arrayToNative(t)));
     }
 
     /**
@@ -797,7 +807,7 @@ public class Context extends IDisposable
     {
         checkContextMatch(t);
         return (ArithExpr) Expr.create(this,
-                Native.mkSub(nCtx(), (int) t.length, AST.arrayToNative(t)));
+                Native.mkSub(nCtx(), t.length, AST.arrayToNative(t)));
     }
 
     /**
@@ -1814,7 +1824,7 @@ public class Context extends IDisposable
     {
         checkContextMatch(args);
         return (ArrayExpr)Expr.create(this,
-                Native.mkSetUnion(nCtx(), (int) args.length,
+                Native.mkSetUnion(nCtx(), args.length,
                         AST.arrayToNative(args)));
     }
 
@@ -1825,7 +1835,7 @@ public class Context extends IDisposable
     {
         checkContextMatch(args);
         return (ArrayExpr)Expr.create(this,
-                Native.mkSetIntersect(nCtx(), (int) args.length,
+                Native.mkSetIntersect(nCtx(), args.length,
                         AST.arrayToNative(args)));
     }
 
@@ -1912,7 +1922,7 @@ public class Context extends IDisposable
     public SeqExpr MkConcat(SeqExpr... t)
     {
 	checkContextMatch(t);
-	return new SeqExpr(this, Native.mkSeqConcat(nCtx(), (int)t.length, AST.arrayToNative(t)));
+	return new SeqExpr(this, Native.mkSeqConcat(nCtx(), t.length, AST.arrayToNative(t)));
     }
     
     
@@ -2040,7 +2050,7 @@ public class Context extends IDisposable
     public ReExpr MkConcat(ReExpr... t)
     {
 	checkContextMatch(t);
-	return new ReExpr(this, Native.mkReConcat(nCtx(), (int)t.length, AST.arrayToNative(t)));
+	return new ReExpr(this, Native.mkReConcat(nCtx(), t.length, AST.arrayToNative(t)));
     }
     
     /**
@@ -2049,7 +2059,7 @@ public class Context extends IDisposable
     public ReExpr MkUnion(ReExpr... t)
     {
 	checkContextMatch(t);
-	return new ReExpr(this, Native.mkReUnion(nCtx(), (int)t.length, AST.arrayToNative(t)));
+	return new ReExpr(this, Native.mkReUnion(nCtx(), t.length, AST.arrayToNative(t)));
     }
     
 
@@ -2258,7 +2268,7 @@ public class Context extends IDisposable
                                Symbol quantifierID, Symbol skolemID)
     {
 
-        return new Quantifier(this, true, sorts, names, body, weight, patterns,
+        return Quantifier.of(this, true, sorts, names, body, weight, patterns,
                 noPatterns, quantifierID, skolemID);
     }
 
@@ -2271,7 +2281,7 @@ public class Context extends IDisposable
                                Symbol skolemID)
     {
 
-        return new Quantifier(this, true, boundConstants, body, weight,
+        return Quantifier.of(this, true, boundConstants, body, weight,
                 patterns, noPatterns, quantifierID, skolemID);
     }
 
@@ -2284,7 +2294,7 @@ public class Context extends IDisposable
                                Symbol quantifierID, Symbol skolemID)
     {
 
-        return new Quantifier(this, false, sorts, names, body, weight,
+        return Quantifier.of(this, false, sorts, names, body, weight,
                 patterns, noPatterns, quantifierID, skolemID);
     }
 
@@ -2297,7 +2307,7 @@ public class Context extends IDisposable
                                Symbol skolemID)
     {
 
-        return new Quantifier(this, false, boundConstants, body, weight,
+        return Quantifier.of(this, false, boundConstants, body, weight,
                 patterns, noPatterns, quantifierID, skolemID);
     }
 
@@ -3814,7 +3824,7 @@ public class Context extends IDisposable
      * must be a native object obtained from Z3 (e.g., through 
      * {@code UnwrapAST}) and that it must have a correct reference count.
      * @see Native#incRef 
-     * @see unwrapAST
+     * @see #unwrapAST
      * @param nativeObject The native pointer to wrap.
      **/
     public AST wrapAST(long nativeObject)
@@ -3869,19 +3879,12 @@ public class Context extends IDisposable
         Native.updateParamValue(nCtx(), id, value);
     }
 
-    protected long m_ctx = 0;
-    protected static final Object creation_lock = new Object();
 
     long nCtx()
     {
         return m_ctx;
     }
 
-    void initContext()
-    {
-        setPrintMode(Z3_ast_print_mode.Z3_PRINT_SMTLIB2_COMPLIANT);
-        Native.setInternalErrorHandler(nCtx());
-    }
 
     void checkContextMatch(Z3Object other)
     {
@@ -3925,110 +3928,103 @@ public class Context extends IDisposable
     private TacticDecRefQueue m_Tactic_DRQ = new TacticDecRefQueue(10);
     private FixedpointDecRefQueue m_Fixedpoint_DRQ = new FixedpointDecRefQueue(10);
     private OptimizeDecRefQueue m_Optimize_DRQ = new OptimizeDecRefQueue(10);
+    private ConstructorDecRefQueue m_Constructor_DRQ = new ConstructorDecRefQueue(10);
+    private ConstructorListDecRefQueue m_ConstructorList_DRQ =
+            new ConstructorListDecRefQueue(10);
 
-    public IDecRefQueue getASTDRQ()
+    public IDecRefQueue<Constructor> getConstructorDRQ() {
+        return m_Constructor_DRQ;
+    }
+
+    public IDecRefQueue<ConstructorList> getConstructorListDRQ() {
+        return m_ConstructorList_DRQ;
+    }
+
+    public IDecRefQueue<AST> getASTDRQ()
     {
         return m_AST_DRQ;
     }
 
-    public IDecRefQueue getASTMapDRQ()
+    public IDecRefQueue<ASTMap> getASTMapDRQ()
     {
         return m_ASTMap_DRQ;
     }
 
-    public IDecRefQueue getASTVectorDRQ()
+    public IDecRefQueue<ASTVector> getASTVectorDRQ()
     {
         return m_ASTVector_DRQ;
     }
 
-    public IDecRefQueue getApplyResultDRQ()
+    public IDecRefQueue<ApplyResult> getApplyResultDRQ()
     {
         return m_ApplyResult_DRQ;
     }
 
-    public IDecRefQueue getFuncEntryDRQ()
+    public IDecRefQueue<FuncInterp.Entry> getFuncEntryDRQ()
     {
         return m_FuncEntry_DRQ;
     }
 
-    public IDecRefQueue getFuncInterpDRQ()
+    public IDecRefQueue<FuncInterp> getFuncInterpDRQ()
     {
         return m_FuncInterp_DRQ;
     }
 
-    public IDecRefQueue getGoalDRQ()
+    public IDecRefQueue<Goal> getGoalDRQ()
     {
         return m_Goal_DRQ;
     }
 
-    public IDecRefQueue getModelDRQ()
+    public IDecRefQueue<Model> getModelDRQ()
     {
         return m_Model_DRQ;
     }
 
-    public IDecRefQueue getParamsDRQ()
+    public IDecRefQueue<Params> getParamsDRQ()
     {
         return m_Params_DRQ;
     }
 
-    public IDecRefQueue getParamDescrsDRQ()
+    public IDecRefQueue<ParamDescrs> getParamDescrsDRQ()
     {
         return m_ParamDescrs_DRQ;
     }
 
-    public IDecRefQueue getProbeDRQ()
+    public IDecRefQueue<Probe> getProbeDRQ()
     {
         return m_Probe_DRQ;
     }
 
-    public IDecRefQueue getSolverDRQ()
+    public IDecRefQueue<Solver> getSolverDRQ()
     {
         return m_Solver_DRQ;
     }
 
-    public IDecRefQueue getStatisticsDRQ()
+    public IDecRefQueue<Statistics> getStatisticsDRQ()
     {
         return m_Statistics_DRQ;
     }
 
-    public IDecRefQueue getTacticDRQ()
+    public IDecRefQueue<Tactic> getTacticDRQ()
     {
         return m_Tactic_DRQ;
     }
 
-    public IDecRefQueue getFixedpointDRQ()
+    public IDecRefQueue<Fixedpoint> getFixedpointDRQ()
     {
         return m_Fixedpoint_DRQ;
     }
 
-    public IDecRefQueue getOptimizeDRQ()
+    public IDecRefQueue<Optimize> getOptimizeDRQ()
     {
         return m_Optimize_DRQ;
     }
 
-    protected AtomicInteger m_refCount = new AtomicInteger(0);
-
-    /**
-     * Finalizer.
-     * @throws Throwable 
-     **/
-    protected void finalize() throws Throwable
-    {
-        try {            
-            dispose();
-        }
-        catch (Throwable t) {
-            throw t;
-        }
-        finally {
-            super.finalize();
-        }
-    }
-
     /**
      * Disposes of the context.
      **/
-    public void dispose()
+    @Override
+    public void close()
     {
         m_AST_DRQ.clear(this);
         m_ASTMap_DRQ.clear(this);
@@ -4052,15 +4048,7 @@ public class Context extends IDisposable
         m_stringSort = null;
 
         synchronized (creation_lock) {
-            if (m_refCount.get() == 0 && m_ctx != 0) {
-                try {
             Native.delContext(m_ctx);
-                } catch (Z3Exception e) {
-                    // OK?
-                    System.out.println("Context deletion failed; memory leak possible.");
-                }
-                m_ctx = 0;
-            }
         }
     }
 }

src/api/java/EnumSort.java

@@ -92,13 +92,9 @@ public class EnumSort extends Sort
 
     EnumSort(Context ctx, Symbol name, Symbol[] enumNames)
     {
-        super(ctx, 0);
+        super(ctx, Native.mkEnumerationSort(ctx.nCtx(),
-
+                name.getNativeObject(), enumNames.length,
-        int n = enumNames.length;
+                Symbol.arrayToNative(enumNames),
-        long[] n_constdecls = new long[n];
+                new long[enumNames.length], new long[enumNames.length]));
-        long[] n_testers = new long[n];
-        setNativeObject(Native.mkEnumerationSort(ctx.nCtx(),
-                name.getNativeObject(), n, Symbol.arrayToNative(enumNames),
-                n_constdecls, n_testers));        
     }
 };

src/api/java/Expr.java

@@ -120,13 +120,13 @@ public class Expr extends AST
      * @param args arguments
      * @throws Z3Exception on error
      **/
-    public void update(Expr[] args)
+    public Expr update(Expr[] args)
     {
         getContext().checkContextMatch(args);
         if (isApp() && args.length != getNumArgs()) {
             throw new Z3Exception("Number of arguments does not match");
         }
-        setNativeObject(Native.updateTerm(getContext().nCtx(), getNativeObject(),
+        return new Expr(getContext(), Native.updateTerm(getContext().nCtx(), getNativeObject(),
                 args.length, Expr.arrayToNative(args)));
     }
 
@@ -2091,36 +2091,23 @@ public class Expr extends AST
      **/
     public int getIndex()
     {
-        if (!isVar())
+        if (!isVar()) {
             throw new Z3Exception("Term is not a bound variable.");
+        }
 
         return Native.getIndexValue(getContext().nCtx(), getNativeObject());
     }
 
-    /**
-     * Constructor for Expr
-     **/
-    protected Expr(Context ctx)
-    {
-        super(ctx);
-        {
-        }
-    }
-
     /**
      * Constructor for Expr
      * @throws Z3Exception on error
      **/
-    protected Expr(Context ctx, long obj)
+    protected Expr(Context ctx, long obj) {
-    {
         super(ctx, obj);
-        {
-        }
     }
 
     @Override
-    void checkNativeObject(long obj)
+    void checkNativeObject(long obj) {
-    {
         if (!Native.isApp(getContext().nCtx(), obj) && 
             Native.getAstKind(getContext().nCtx(), obj) != Z3_ast_kind.Z3_VAR_AST.toInt() &&
             Native.getAstKind(getContext().nCtx(), obj) != Z3_ast_kind.Z3_QUANTIFIER_AST.toInt()) {

src/api/java/FPNum.java

@@ -28,7 +28,7 @@ public class FPNum extends FPExpr
      */
     public boolean getSign() {
         Native.IntPtr res = new Native.IntPtr();
-        if (Native.fpaGetNumeralSign(getContext().nCtx(), getNativeObject(), res) ^ true)                
+        if (!Native.fpaGetNumeralSign(getContext().nCtx(), getNativeObject(), res))
             throw new Z3Exception("Sign is not a Boolean value");
         return res.value != 0;
     }
@@ -53,7 +53,7 @@ public class FPNum extends FPExpr
     public long getSignificandUInt64()
     {
         Native.LongPtr res = new Native.LongPtr();
-        if (Native.fpaGetNumeralSignificandUint64(getContext().nCtx(), getNativeObject(), res) ^ true)
+        if (!Native.fpaGetNumeralSignificandUint64(getContext().nCtx(), getNativeObject(), res))
             throw new Z3Exception("Significand is not a 64 bit unsigned integer");
         return res.value;
     }
@@ -72,7 +72,7 @@ public class FPNum extends FPExpr
      */
     public long getExponentInt64()  {
         Native.LongPtr res = new Native.LongPtr();
-        if (Native.fpaGetNumeralExponentInt64(getContext().nCtx(), getNativeObject(), res) ^ true)
+        if (!Native.fpaGetNumeralExponentInt64(getContext().nCtx(), getNativeObject(), res))
             throw new Z3Exception("Exponent is not a 64 bit integer");
         return res.value;
     }

src/api/java/Fixedpoint.java

@@ -349,16 +349,11 @@ public class Fixedpoint extends Z3Object
     }
 
     @Override
-    void incRef(long o)
+    void incRef(long o) {
-    {
+        Native.fixedpointIncRef(getContext().nCtx(), o);
-        getContext().getFixedpointDRQ().incAndClear(getContext(), o);
+        getContext().getFixedpointDRQ().storeReference(getContext(), this);
-        super.incRef(o);
     }
 
     @Override
-    void decRef(long o)
+    void checkNativeObject(long obj) { }
-    {
-        getContext().getFixedpointDRQ().add(o);
-        super.decRef(o);
-    }
 }

src/api/java/FixedpointDecRefQueue.java

@@ -17,7 +17,7 @@ Notes:
 
 package com.microsoft.z3;
 
-class FixedpointDecRefQueue extends IDecRefQueue
+class FixedpointDecRefQueue extends IDecRefQueue<Fixedpoint>
 {
     public FixedpointDecRefQueue() 
     {
@@ -29,27 +29,10 @@ class FixedpointDecRefQueue extends IDecRefQueue
         super(move_limit);
     }
 
-    @Override
-    protected void incRef(Context ctx, long obj)
-    {
-        try
-        {
-            Native.fixedpointIncRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
-    }
 
     @Override
     protected void decRef(Context ctx, long obj)
-    {
-        try
     {
         Native.fixedpointDecRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
     }
 };

src/api/java/FuncInterp.java

@@ -72,8 +72,6 @@ public class FuncInterp extends Z3Object
          **/
         @Override
         public String toString()
-        {
-            try
         {
             int n = getNumArgs();
             String res = "[";
@@ -81,10 +79,6 @@ public class FuncInterp extends Z3Object
             for (int i = 0; i < n; i++)
                 res += args[i] + ", ";
             return res + getValue() + "]";
-            } catch (Z3Exception e)
-            {
-                return "Z3Exception: " + e.getMessage();
-            }
         }
 
         Entry(Context ctx, long obj)
@@ -93,17 +87,9 @@ public class FuncInterp extends Z3Object
         }
 
         @Override
-        void incRef(long o)
+        void incRef(long o) {
-        {
+            Native.funcEntryIncRef(getContext().nCtx(), o);;
-            getContext().getFuncEntryDRQ().incAndClear(getContext(), o);
+            getContext().getFuncEntryDRQ().storeReference(getContext(), this);
-            super.incRef(o);
-        }
-
-        @Override
-        void decRef(long o)
-        {
-            getContext().getFuncEntryDRQ().add(o);
-            super.decRef(o);
         }
     }
 
@@ -160,8 +146,6 @@ public class FuncInterp extends Z3Object
      * A string representation of the function interpretation.
      **/
     public String toString()
-    {
-        try
     {
         String res = "";
         res += "[";
@@ -184,10 +168,6 @@ public class FuncInterp extends Z3Object
         res += "else -> " + getElse();
         res += "]";
         return res;
-        } catch (Z3Exception e)
-        {
-            return "Z3Exception: " + e.getMessage();
-        }
     }
 
     FuncInterp(Context ctx, long obj)
@@ -196,16 +176,8 @@ public class FuncInterp extends Z3Object
     }
 
     @Override
-    void incRef(long o)
+    void incRef(long o) {
-    {
+        Native.funcInterpIncRef(getContext().nCtx(), o);
-        getContext().getFuncInterpDRQ().incAndClear(getContext(), o);
+        getContext().getFuncInterpDRQ().storeReference(getContext(), this);
-        super.incRef(o);
-    }
-
-    @Override
-    void decRef(long o)
-    {
-        getContext().getFuncInterpDRQ().add(o);
-        super.decRef(o);
     }
 }

src/api/java/FuncInterpDecRefQueue.java

@@ -17,7 +17,7 @@ Notes:
 
 package com.microsoft.z3;
 
-class FuncInterpDecRefQueue extends IDecRefQueue
+class FuncInterpDecRefQueue extends IDecRefQueue<FuncInterp>
 {
     public FuncInterpDecRefQueue() 
     {
@@ -30,26 +30,7 @@ class FuncInterpDecRefQueue extends IDecRefQueue
     }
 
     @Override
-    protected void incRef(Context ctx, long obj)
+    protected void decRef(Context ctx, long obj) {
-    {
-        try
-        {
-            Native.funcInterpIncRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
-    }
-
-    @Override
-    protected void decRef(Context ctx, long obj)
-    {
-        try
-        {
         Native.funcInterpDecRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
     }
 };

src/api/java/FuncInterpEntryDecRefQueue.java

@@ -17,7 +17,7 @@ Notes:
 
 package com.microsoft.z3;
 
-class FuncInterpEntryDecRefQueue extends IDecRefQueue
+class FuncInterpEntryDecRefQueue extends IDecRefQueue<FuncInterp.Entry>
 {
     public FuncInterpEntryDecRefQueue() 
     {
@@ -30,26 +30,7 @@ class FuncInterpEntryDecRefQueue extends IDecRefQueue
     }
 
     @Override
-    protected void incRef(Context ctx, long obj)
+    protected void decRef(Context ctx, long obj) {
-    {
-        try
-        {
-            Native.funcEntryIncRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
-    }
-
-    @Override
-    protected void decRef(Context ctx, long obj)
-    {
-        try
-        {
         Native.funcEntryDecRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
     }
 };

src/api/java/Goal.java

@@ -222,11 +222,11 @@ public class Goal extends Z3Object
      **/
     public BoolExpr AsBoolExpr() {
         int n = size();
-        if (n == 0) 
+        if (n == 0) {
             return getContext().mkTrue();
-        else if (n == 1)                
+        } else if (n == 1) {
             return getFormulas()[0];
-        else {
+        } else {
             return getContext().mkAnd(getFormulas());
         }
     }
@@ -236,23 +236,14 @@ public class Goal extends Z3Object
         super(ctx, obj);
     }
 
-    Goal(Context ctx, boolean models, boolean unsatCores, boolean proofs)
+    Goal(Context ctx, boolean models, boolean unsatCores, boolean proofs) {
-           
-    {
         super(ctx, Native.mkGoal(ctx.nCtx(), (models),
             (unsatCores), (proofs)));
     }
 
-    void incRef(long o)
+    @Override
-    {
+    void incRef(long o) {
-        getContext().getGoalDRQ().incAndClear(getContext(), o);
+        Native.goalIncRef(getContext().nCtx(), o);
-        super.incRef(o);
+        getContext().getGoalDRQ().storeReference(getContext(), this);
     }
-
-    void decRef(long o)
-    {
-        getContext().getGoalDRQ().add(o);
-        super.decRef(o);
-    }
-
 }

src/api/java/GoalDecRefQueue.java

@@ -17,7 +17,7 @@ Notes:
 
 package com.microsoft.z3;
 
-class GoalDecRefQueue extends IDecRefQueue
+class GoalDecRefQueue extends IDecRefQueue<Goal>
 {
     public GoalDecRefQueue() 
     {
@@ -30,26 +30,7 @@ class GoalDecRefQueue extends IDecRefQueue
     }
 
     @Override
-    protected void incRef(Context ctx, long obj)
+    protected void decRef(Context ctx, long obj) {
-    {
-        try
-        {
-            Native.goalIncRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
-    }
-
-    @Override
-    protected void decRef(Context ctx, long obj)
-    {
-        try
-        {
             Native.goalDecRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
     }
 };

src/api/java/IDecRefQueue.java

@@ -17,13 +17,21 @@ Notes:
 
 package com.microsoft.z3;
 
-import java.util.LinkedList;
+import java.lang.ref.PhantomReference;
+import java.lang.ref.Reference;
+import java.lang.ref.ReferenceQueue;
+import java.util.IdentityHashMap;
+import java.util.Map;
 
-public abstract class IDecRefQueue
+public abstract class IDecRefQueue<T extends Z3Object>
 {
-    protected final Object m_lock = new Object();
+    private final int m_move_limit;
-    protected LinkedList<Long> m_queue = new LinkedList<Long>();
+
-    protected int m_move_limit;
+    // TODO: problem: ReferenceQueue has no API to return length.
+    private final ReferenceQueue<T> referenceQueue = new ReferenceQueue<>();
+    private int queueSize = 0;
+    private final Map<PhantomReference<T>, Long> referenceMap =
+            new IdentityHashMap<>();
 
     protected IDecRefQueue() 
 	{
@@ -35,37 +43,30 @@ public abstract class IDecRefQueue
     	m_move_limit = move_limit;
     }
 
-    public void setLimit(int l) { m_move_limit = l; }
+    /**
- 
+     * An implementation of this method should decrement the reference on a
-    protected abstract void incRef(Context ctx, long obj);
+     * given native object.
-
+     * This function should be always called on the {@code ctx} thread.
+     *
+     * @param ctx Z3 context.
+     * @param obj Pointer to a Z3 object.
+     */
     protected abstract void decRef(Context ctx, long obj);
 
-    protected void incAndClear(Context ctx, long o)
+    public void storeReference(Context ctx, T obj) {
-    {
+        PhantomReference<T> ref = new PhantomReference<>(obj, referenceQueue);
-        incRef(ctx, o);
+        referenceMap.put(ref, obj.getNativeObject());
-        if (m_queue.size() >= m_move_limit)
+
+        // TODO: use move_limit, somehow get the size of referenceQueue.
         clear(ctx);
     }
 
-    protected void add(long o)
-    {
-        if (o == 0)
-            return;
-
-        synchronized (m_lock)
-        {
-            m_queue.add(o);
-        }
-    }
-
     protected void clear(Context ctx)
     {
-        synchronized (m_lock)
+        Reference<? extends T> ref;
-        {
+        while ((ref = referenceQueue.poll()) != null) {
-            for (Long o : m_queue)
+            long z3ast = referenceMap.remove(ref);
-                decRef(ctx, o);
+            decRef(ctx, z3ast);
-            m_queue.clear();
         }
     }
 }

src/api/java/IDisposable.java

@@ -1,25 +0,0 @@
-/*++
-Copyright (c) 2012 Microsoft Corporation
-
-Module Name:
-
-    IDisposable.java
-
-Abstract:
-
-    Compatability interface (C# -> Java)
-
-Author:
-
-    Christoph Wintersteiger (cwinter) 2012-03-16
-
-Notes:
-    
---*/
-
-package com.microsoft.z3;
-
-public abstract class IDisposable
-{
-    public abstract void dispose();
-}

src/api/java/InterpolationContext.java

@@ -17,11 +17,10 @@ Notes:
 
 package com.microsoft.z3;
 
-import java.util.Map;
-import java.lang.String;
-
 import com.microsoft.z3.enumerations.Z3_lbool;
 
+import java.util.Map;
+
 /** 
  *  The InterpolationContext is suitable for generation of interpolants.
  *
@@ -33,13 +32,13 @@ public class InterpolationContext extends Context
     /**
      * Constructor.
      **/
-    public InterpolationContext()
+    public static InterpolationContext mkContext()
     {
-        super();
+        long m_ctx;
         synchronized(creation_lock) {
             m_ctx = Native.mkInterpolationContext(0);
-            initContext(); 
         }
+        return new InterpolationContext(m_ctx);
     }
 
     /** 
@@ -49,17 +48,21 @@ public class InterpolationContext extends Context
      * Remarks: 
      * @see Context#Context
      **/
-    public InterpolationContext(Map<String, String> settings)
+    public static InterpolationContext mkContext(Map<String, String> settings)
     { 
-        super();
+        long m_ctx;
         synchronized(creation_lock) {
             long cfg = Native.mkConfig();
             for (Map.Entry<String, String> kv : settings.entrySet())
                 Native.setParamValue(cfg, kv.getKey(), kv.getValue());
             m_ctx = Native.mkInterpolationContext(cfg);
             Native.delConfig(cfg);
-            initContext();
         }
+        return new InterpolationContext(m_ctx);
+    }
+
+    private InterpolationContext(long m_ctx) {
+        super(m_ctx);
     }
 
     /** 

src/api/java/ListSort.java

@@ -17,6 +17,8 @@ Notes:
 
 package com.microsoft.z3;
 
+import com.microsoft.z3.Native.LongPtr;
+
 /**
  * List sorts.
  **/
@@ -88,14 +90,9 @@ public class ListSort extends Sort
 
     ListSort(Context ctx, Symbol name, Sort elemSort)
     {
-        super(ctx, 0);
+        super(ctx, Native.mkListSort(ctx.nCtx(), name.getNativeObject(),
-
+                elemSort.getNativeObject(),
-        Native.LongPtr inil = new Native.LongPtr(), iisnil = new Native.LongPtr();
+                new LongPtr(), new Native.LongPtr(), new LongPtr(),
-        Native.LongPtr icons = new Native.LongPtr(), iiscons = new Native.LongPtr();
+                new LongPtr(), new LongPtr(), new LongPtr()));
-        Native.LongPtr ihead = new Native.LongPtr(), itail = new Native.LongPtr();
-
-        setNativeObject(Native.mkListSort(ctx.nCtx(), name.getNativeObject(),
-                elemSort.getNativeObject(), inil, iisnil, icons, iiscons, ihead,
-                itail));
     }
 };

src/api/java/Model.java

@@ -293,16 +293,8 @@ public class Model extends Z3Object
     }
 
     @Override
-    void incRef(long o)
+    void incRef(long o) {
-    {
+        Native.modelIncRef(getContext().nCtx(), o);
-        getContext().getModelDRQ().incAndClear(getContext(), o);
+        getContext().getModelDRQ().storeReference(getContext(), this);
-        super.incRef(o);
-    }
-
-    @Override
-    void decRef(long o)
-    {
-        getContext().getModelDRQ().add(o);
-        super.decRef(o);
     }
 }

src/api/java/ModelDecRefQueue.java

@@ -17,7 +17,7 @@ Notes:
 
 package com.microsoft.z3;
 
-class ModelDecRefQueue extends IDecRefQueue
+class ModelDecRefQueue extends IDecRefQueue<Model>
 {
     public ModelDecRefQueue() 
     {
@@ -30,26 +30,7 @@ class ModelDecRefQueue extends IDecRefQueue
     }
 
     @Override
-    protected void incRef(Context ctx, long obj)
+    protected void decRef(Context ctx, long obj) {
-    {
-        try
-        {
-            Native.modelIncRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
-    }
-
-    @Override
-    protected void decRef(Context ctx, long obj)
-    {
-        try
-        {
         Native.modelDecRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
     }
 };

src/api/java/Optimize.java

@@ -266,17 +266,8 @@ public class Optimize extends Z3Object
     }
 
     @Override
-    void incRef(long o)
+    void incRef(long o) {
-    {
+        Native.optimizeIncRef(getContext().nCtx(), o);
-        getContext().getOptimizeDRQ().incAndClear(getContext(), o);
+        getContext().getOptimizeDRQ().storeReference(getContext(), this);
-        super.incRef(o);
     }
-
-    @Override
-    void decRef(long o)
-    {
-        getContext().getOptimizeDRQ().add(o);
-        super.decRef(o);
-    }
-
 }

src/api/java/OptimizeDecRefQueue.java

@@ -17,8 +17,7 @@ Notes:
 
 package com.microsoft.z3;
 
-class OptimizeDecRefQueue extends IDecRefQueue
+class OptimizeDecRefQueue extends IDecRefQueue<Optimize> {
-{
     public OptimizeDecRefQueue() 
     {
         super();
@@ -30,26 +29,7 @@ class OptimizeDecRefQueue extends IDecRefQueue
     }
 
     @Override
-    protected void incRef(Context ctx, long obj)
+    protected void decRef(Context ctx, long obj) {
-    {
+        Native.optimizeDecRef(ctx.nCtx(), obj);
-        try
-        {
-            Native.fixedpointIncRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
-    }
-
-    @Override
-    protected void decRef(Context ctx, long obj)
-    {
-        try
-        {
-            Native.fixedpointDecRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
     }
 };

src/api/java/ParamDescrs.java

@@ -92,16 +92,8 @@ public class ParamDescrs extends Z3Object
     }
 
     @Override
-    void incRef(long o)
+    void incRef(long o) {
-    {
+        Native.paramDescrsIncRef(getContext().nCtx(), o);
-        getContext().getParamDescrsDRQ().incAndClear(getContext(), o);
+        getContext().getParamDescrsDRQ().storeReference(getContext(), this);
-        super.incRef(o);
-    }
-
-    @Override
-    void decRef(long o)
-    {
-        getContext().getParamDescrsDRQ().add(o);
-        super.decRef(o);
     }
 }

src/api/java/ParamDescrsDecRefQueue.java

@@ -17,39 +17,20 @@ Notes:
 
 package com.microsoft.z3;
 
-class ParamDescrsDecRefQueue extends IDecRefQueue
+class ParamDescrsDecRefQueue extends IDecRefQueue<ParamDescrs>
 {
     public ParamDescrsDecRefQueue() 
     {
         super();
     }
 
-    public ParamDescrsDecRefQueue(int move_limit) 
+    public ParamDescrsDecRefQueue(int move_limit) {
-    {
         super(move_limit);
     }
 
-    @Override
-    protected void incRef(Context ctx, long obj)
-    {
-        try
-        {
-            Native.paramDescrsIncRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
-    }
-
     @Override
     protected void decRef(Context ctx, long obj)
-    {
-        try
     {
         Native.paramDescrsDecRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
     }
 };

src/api/java/Params.java

@@ -124,16 +124,8 @@ public class Params extends Z3Object
     }
 
     @Override
-    void incRef(long o)
+    void incRef(long o) {
-    {
+        Native.paramsIncRef(getContext().nCtx(), o);
-        getContext().getParamsDRQ().incAndClear(getContext(), o);
+        getContext().getParamsDRQ().storeReference(getContext(), this);
-        super.incRef(o);
-    }
-
-    @Override
-    void decRef(long o)
-    {
-        getContext().getParamsDRQ().add(o);
-        super.decRef(o);
     }
 }

src/api/java/ParamsDecRefQueue.java

@@ -17,7 +17,7 @@ Notes:
 
 package com.microsoft.z3;
 
-class ParamsDecRefQueue extends IDecRefQueue
+class ParamsDecRefQueue extends IDecRefQueue<Params>
 {
     public ParamsDecRefQueue() 
     {
@@ -30,26 +30,7 @@ class ParamsDecRefQueue extends IDecRefQueue
     }
 
     @Override
-    protected void incRef(Context ctx, long obj)
+    protected void decRef(Context ctx, long obj) {
-    {
-        try
-        {
-            Native.paramsIncRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
-    }
-
-    @Override
-    protected void decRef(Context ctx, long obj)
-    {
-        try
-        {
         Native.paramsDecRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
     }
 };

src/api/java/Probe.java

@@ -54,14 +54,7 @@ public class Probe extends Z3Object
     @Override
     void incRef(long o)
     {
-        getContext().getProbeDRQ().incAndClear(getContext(), o);
+        Native.probeIncRef(getContext().nCtx(), o);
-        super.incRef(o);
+        getContext().getProbeDRQ().storeReference(getContext(), this);
-    }
-
-    @Override
-    void decRef(long o)
-    {
-        getContext().getProbeDRQ().add(o);
-        super.decRef(o);
     }
 }

src/api/java/ProbeDecRefQueue.java

@@ -17,7 +17,7 @@ Notes:
 
 package com.microsoft.z3;
 
-class ProbeDecRefQueue extends IDecRefQueue
+class ProbeDecRefQueue extends IDecRefQueue<Probe>
 {
     public ProbeDecRefQueue() 
     {
@@ -29,27 +29,9 @@ class ProbeDecRefQueue extends IDecRefQueue
         super(move_limit);
     }
 
-    @Override
-    protected void incRef(Context ctx, long obj)
-    {
-        try
-        {
-            Native.probeIncRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
-    }
-
     @Override
     protected void decRef(Context ctx, long obj)
-    {
-        try
     {
         Native.probeDecRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
     }
 };

src/api/java/Quantifier.java

@@ -145,68 +145,67 @@ public class Quantifier extends BoolExpr
                 .nCtx(), getNativeObject()));
     }
 
-    Quantifier(Context ctx, boolean isForall, Sort[] sorts, Symbol[] names,
+    public static Quantifier of(
+            Context ctx, boolean isForall, Sort[] sorts, Symbol[] names,
             Expr body, int weight, Pattern[] patterns, Expr[] noPatterns,
-            Symbol quantifierID, Symbol skolemID)
+            Symbol quantifierID, Symbol skolemID
-    {
+    ) {
-        super(ctx, 0);
+        ctx.checkContextMatch(patterns);
-
+        ctx.checkContextMatch(noPatterns);
-        getContext().checkContextMatch(patterns);
+        ctx.checkContextMatch(sorts);
-        getContext().checkContextMatch(noPatterns);
+        ctx.checkContextMatch(names);
-        getContext().checkContextMatch(sorts);
+        ctx.checkContextMatch(body);
-        getContext().checkContextMatch(names);
-        getContext().checkContextMatch(body);
 
         if (sorts.length != names.length)
             throw new Z3Exception(
                     "Number of sorts does not match number of names");
 
-        if (noPatterns == null && quantifierID == null && skolemID == null)
+        long nativeObj;
-        {
+        if (noPatterns == null && quantifierID == null && skolemID == null) {
-            setNativeObject(Native.mkQuantifier(ctx.nCtx(), (isForall), weight, AST.arrayLength(patterns), AST
+            nativeObj = Native.mkQuantifier(ctx.nCtx(), (isForall), weight, AST.arrayLength(patterns), AST
                     .arrayToNative(patterns), AST.arrayLength(sorts), AST
                     .arrayToNative(sorts), Symbol.arrayToNative(names), body
-                    .getNativeObject()));
+                    .getNativeObject());
-        } else
+        } else {
-        {
+            nativeObj = Native.mkQuantifierEx(ctx.nCtx(),
-            setNativeObject(Native.mkQuantifierEx(ctx.nCtx(),
                     (isForall), weight, AST.getNativeObject(quantifierID),
                     AST.getNativeObject(skolemID),
                     AST.arrayLength(patterns), AST.arrayToNative(patterns),
                     AST.arrayLength(noPatterns), AST.arrayToNative(noPatterns),
                     AST.arrayLength(sorts), AST.arrayToNative(sorts),
                     Symbol.arrayToNative(names),
-             body.getNativeObject()));
+                    body.getNativeObject());
         }
+        return new Quantifier(ctx, nativeObj);
     }
 
-    Quantifier(Context ctx, boolean isForall, Expr[] bound, Expr body,
+
+    public static Quantifier of(Context ctx, boolean isForall, Expr[] bound, Expr body,
             int weight, Pattern[] patterns, Expr[] noPatterns,
             Symbol quantifierID, Symbol skolemID)
     {
-        super(ctx, 0);
+        ctx.checkContextMatch(noPatterns);
-
+        ctx.checkContextMatch(patterns);
-        getContext().checkContextMatch(noPatterns);
+        // ctx.CheckContextMatch(bound);
-        getContext().checkContextMatch(patterns);
+        ctx.checkContextMatch(body);
-        // Context().CheckContextMatch(bound);
-        getContext().checkContextMatch(body);
 
+        long nativeObj;
         if (noPatterns == null && quantifierID == null && skolemID == null)
         {
-            setNativeObject(Native.mkQuantifierConst(ctx.nCtx(),
+            nativeObj = Native.mkQuantifierConst(ctx.nCtx(),
                 isForall, weight, AST.arrayLength(bound),
                     AST.arrayToNative(bound), AST.arrayLength(patterns),
-                    AST.arrayToNative(patterns), body.getNativeObject()));
+                    AST.arrayToNative(patterns), body.getNativeObject());
-        } else
+        } else {
-        {
+            nativeObj = Native.mkQuantifierConstEx(ctx.nCtx(),
-            setNativeObject(Native.mkQuantifierConstEx(ctx.nCtx(),
                 isForall, weight,
                     AST.getNativeObject(quantifierID),
                     AST.getNativeObject(skolemID), AST.arrayLength(bound),
                     AST.arrayToNative(bound), AST.arrayLength(patterns),
                     AST.arrayToNative(patterns), AST.arrayLength(noPatterns),
-                    AST.arrayToNative(noPatterns), body.getNativeObject()));
+                    AST.arrayToNative(noPatterns), body.getNativeObject());
         }
+        return new Quantifier(ctx, nativeObj);
     }
 
     Quantifier(Context ctx, long obj)

src/api/java/Solver.java

@@ -127,13 +127,13 @@ public class Solver extends Z3Object
      * using the Boolean constants in ps.
      *
      * Remarks: 
-     * This API is an alternative to {@link check} with assumptions for
+     * This API is an alternative to {@link #check()} with assumptions for
      * extracting unsat cores.
      * Both APIs can be used in the same solver. The unsat core will contain a
      * combination
-     * of the Boolean variables provided using {@link assertAndTrack}
+     * of the Boolean variables provided using {@code #assertAndTrack}
      * and the Boolean literals
-     * provided using {@link check} with assumptions.
+     * provided using {@link #check()} with assumptions.
      **/
     public void assertAndTrack(BoolExpr[] constraints, BoolExpr[] ps)
     {
@@ -333,16 +333,8 @@ public class Solver extends Z3Object
     }
 
     @Override
-    void incRef(long o)
+    void incRef(long o) {
-    {
+        Native.solverIncRef(getContext().nCtx(), o);
-        getContext().getSolverDRQ().incAndClear(getContext(), o);
+        getContext().getSolverDRQ().storeReference(getContext(), this);
-        super.incRef(o);
-    }
-
-    @Override
-    void decRef(long o)
-    {
-        getContext().getSolverDRQ().add(o);
-        super.decRef(o);
     }
 }

src/api/java/SolverDecRefQueue.java

@@ -17,7 +17,7 @@ Notes:
 
 package com.microsoft.z3;
 
-class SolverDecRefQueue extends IDecRefQueue
+class SolverDecRefQueue extends IDecRefQueue<Solver>
 {
     public SolverDecRefQueue() { super(); }
     
@@ -27,26 +27,7 @@ class SolverDecRefQueue extends IDecRefQueue
     }
 
     @Override
-    protected void incRef(Context ctx, long obj)
+    protected void decRef(Context ctx, long obj) {
-    {
-        try
-        {
-            Native.solverIncRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
-    }
-
-    @Override
-    protected void decRef(Context ctx, long obj)
-    {
-        try
-        {
         Native.solverDecRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
     }
 };

src/api/java/Sort.java

@@ -95,6 +95,7 @@ public class Sort extends AST
         super(ctx, obj);
     }
 
+    @Override
     void checkNativeObject(long obj)
     {
         if (Native.getAstKind(getContext().nCtx(), obj) != Z3_ast_kind.Z3_SORT_AST

src/api/java/Statistics.java

@@ -190,15 +190,9 @@ public class Statistics extends Z3Object
         super(ctx, obj);
     }
 
-    void incRef(long o)
+    @Override
-    {
+    void incRef(long o) {
-        getContext().getStatisticsDRQ().incAndClear(getContext(), o);
+        Native.statsIncRef(getContext().nCtx(), o);
-        super.incRef(o);
+        getContext().getStatisticsDRQ().storeReference(getContext(), this);
-    }
-
-    void decRef(long o)
-    {
-        getContext().getStatisticsDRQ().add(o);
-        super.decRef(o);
     }
 }

src/api/java/StatisticsDecRefQueue.java

@@ -17,7 +17,7 @@ Notes:
 
 package com.microsoft.z3;
 
-class StatisticsDecRefQueue extends IDecRefQueue
+class StatisticsDecRefQueue extends IDecRefQueue<Statistics>
 {
     public StatisticsDecRefQueue() 
     {
@@ -29,25 +29,8 @@ class StatisticsDecRefQueue extends IDecRefQueue
         super(move_limit);
     }
 
-    protected void incRef(Context ctx, long obj)
+    @Override
-    {
+    protected void decRef(Context ctx, long obj) {
-        try
-        {
-            Native.statsIncRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
-    }
-
-    protected void decRef(Context ctx, long obj)
-    {
-        try
-        {
         Native.statsDecRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
     }
 };

src/api/java/StringSymbol.java

@@ -48,9 +48,9 @@ public class StringSymbol extends Symbol
     void checkNativeObject(long obj)
     {
         if (Native.getSymbolKind(getContext().nCtx(), obj) != Z3_symbol_kind.Z3_STRING_SYMBOL
-                .toInt())
+                .toInt()) {
             throw new Z3Exception("Symbol is not of String kind");
-
+        }
         super.checkNativeObject(obj);
     }
 }

src/api/java/Symbol.java

@@ -62,19 +62,13 @@ public class Symbol extends Z3Object
      * A string representation of the symbol.
      **/
     @Override
-    public String toString()
+    public String toString() {
-    {
+        if (isIntSymbol()) {
-        try
-        {
-            if (isIntSymbol())
             return Integer.toString(((IntSymbol) this).getInt());
-            else if (isStringSymbol())
+        } else if (isStringSymbol()) {
             return ((StringSymbol) this).getString();
-            else
+        } else {
             return "Z3Exception: Unknown symbol kind encountered.";
-        } catch (Z3Exception ex)
-        {
-            return "Z3Exception: " + ex.getMessage();
         }
     }
 
@@ -86,6 +80,11 @@ public class Symbol extends Z3Object
         super(ctx, obj);
     }
 
+    @Override
+    void incRef(long o) {
+        // Symbol does not require tracking.
+    }
+
     static Symbol create(Context ctx, long obj)
     {
         switch (Z3_symbol_kind.fromInt(Native.getSymbolKind(ctx.nCtx(), obj)))

src/api/java/Tactic.java

@@ -92,15 +92,10 @@ public class Tactic extends Z3Object
         super(ctx, Native.mkTactic(ctx.nCtx(), name));
     }
 
+    @Override
     void incRef(long o)
     {
-        getContext().getTacticDRQ().incAndClear(getContext(), o);
+        Native.tacticIncRef(getContext().nCtx(), o);
-        super.incRef(o);
+        getContext().getTacticDRQ().storeReference(getContext(), this);
-    }
-
-    void decRef(long o)
-    {
-        getContext().getTacticDRQ().add(o);
-        super.decRef(o);
     }
 }

src/api/java/TacticDecRefQueue.java

@@ -17,8 +17,7 @@ Notes:
 
 package com.microsoft.z3;
 
-class TacticDecRefQueue extends IDecRefQueue
+class TacticDecRefQueue extends IDecRefQueue<Tactic> {
-{
     public TacticDecRefQueue() 
     {
         super();
@@ -29,25 +28,9 @@ class TacticDecRefQueue extends IDecRefQueue
         super(move_limit);
     }
 
-    protected void incRef(Context ctx, long obj)
+    @Override
-    {
-        try
-        {
-            Native.tacticIncRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
-        }
-    }
-
     protected void decRef(Context ctx, long obj)
-    {
-        try
     {
         Native.tacticDecRef(ctx.nCtx(), obj);
-        } catch (Z3Exception e)
-        {
-            // OK.
     }
-    }
+}
-};

src/api/java/TupleSort.java

@@ -59,11 +59,9 @@ public class TupleSort extends Sort
     TupleSort(Context ctx, Symbol name, int numFields, Symbol[] fieldNames,
             Sort[] fieldSorts)
     {
-        super(ctx, 0);
+        super(ctx, Native.mkTupleSort(ctx.nCtx(), name.getNativeObject(),
-
-        Native.LongPtr t = new Native.LongPtr();
-        setNativeObject(Native.mkTupleSort(ctx.nCtx(), name.getNativeObject(),
                 numFields, Symbol.arrayToNative(fieldNames),
-                AST.arrayToNative(fieldSorts), t, new long[numFields]));
+                AST.arrayToNative(fieldSorts), new Native.LongPtr(),
+                new long[numFields]));
     }
 };

src/api/java/Z3Object.java

@@ -21,88 +21,38 @@ package com.microsoft.z3;
  * Internal base class for interfacing with native Z3 objects. Should not be
  * used externally.
  **/
-public class Z3Object extends IDisposable
+public abstract class Z3Object {
-{
-    /**
-     * Finalizer.
-     * @throws Throwable 
-     **/
-    protected void finalize() throws Throwable
-    {
-        try {
-            dispose();            
-        } finally {
-            super.finalize();
-        }
-    }
 
-    /**
+    private final Context m_ctx;
-     * Disposes of the underlying native Z3 object.
+    private final long m_n_obj;
-     **/
-    public void dispose()
-    {
-        if (m_n_obj != 0)
-        {
-            decRef(m_n_obj);
-            m_n_obj = 0;
-        }
 
-        if (m_ctx != null)
+    Z3Object(Context ctx, long obj) {
-        {            
-            if (m_ctx.m_refCount.decrementAndGet() == 0)
-                m_ctx.dispose();
-            m_ctx = null;
-        }
-    }
-
-    private Context m_ctx = null;
-    private long m_n_obj = 0;
-
-    Z3Object(Context ctx)
-    {
-        ctx.m_refCount.incrementAndGet();
-        m_ctx = ctx;
-    }
-
-    Z3Object(Context ctx, long obj)
-    {
-        ctx.m_refCount.incrementAndGet();
         m_ctx = ctx;
+        checkNativeObject(obj);
         incRef(obj);
         m_n_obj = obj;
     }
 
-    void incRef(long o)
+    /**
-    {
+     * Increment reference count on {@code o}.
-    }
+     *
+     * @param o Z3 object.
+     */
+    abstract void incRef(long o);
 
-    void decRef(long o)
+    /**
-    {
+     * This function is provided for overriding, and a child class
-    }
+     * can insert consistency checks on {@code obj}.
-
+     *
-    void checkNativeObject(long obj)
+     * @param obj Z3 native object.
-    {
+     */
-    }
+    void checkNativeObject(long obj) {}
 
     long getNativeObject()
     {
         return m_n_obj;
     }
 
-    void setNativeObject(long value)
-    {
-        if (value != 0)
-        {
-            checkNativeObject(value);
-            incRef(value);
-        }
-        if (m_n_obj != 0)
-        {
-            decRef(m_n_obj);
-        }
-        m_n_obj = value;
-    }
-
     static long getNativeObject(Z3Object s)
     {
         if (s == null)