Bugfix for object finalization in Java API.

Relates to #205 and #245

src/api/java/AST.java

@@ -41,13 +41,12 @@ public class AST extends Z3Object implements Comparable
             return false;
         }
 
-	return  
-	    (this == casted) || 
+        return  (this == casted) ||
                 (this != null) &&
                 (casted != null) &&
                 (getContext().nCtx() == casted.getContext().nCtx()) &&
                 (Native.isEqAst(getContext().nCtx(), getNativeObject(), casted.getNativeObject()));
-}
+    }
 
     /**
      * Object Comparison. 

src/api/java/Constructor.java

@@ -80,12 +80,21 @@ public class Constructor extends Z3Object
 
     /**
      * Destructor.
+     * @throws Throwable 
      * @throws Z3Exception on error
      **/
-    protected void finalize()
+    protected void finalize() throws Throwable
     {
+        try {
             Native.delConstructor(getContext().nCtx(), getNativeObject());
         }
+        catch (Throwable t) {
+            throw t;
+        }
+        finally {
+            super.finalize();
+        }
+    }
 
     private int n = 0;
 

src/api/java/ConstructorList.java

@@ -24,12 +24,21 @@ public class ConstructorList extends Z3Object
 {
     /**
      * Destructor.
+     * @throws Throwable 
      * @throws Z3Exception on error
      **/
-    protected void finalize()
+    protected void finalize() throws Throwable
     {
+        try {        
             Native.delConstructorList(getContext().nCtx(), getNativeObject());            
         }
+        catch (Throwable t) {
+            throw t;
+        }
+        finally {
+            super.finalize();
+        }
+    }
 
     ConstructorList(Context ctx, long obj)
     {

src/api/java/Z3Object.java

@@ -25,11 +25,20 @@ public class Z3Object extends IDisposable
 {
     /**
      * Finalizer.
+     * @throws Throwable 
      **/
-    protected void finalize()
+    protected void finalize() throws Throwable
     {
+        try {
             dispose();            
         }
+        catch (Throwable t) {
+            throw t;
+        }
+        finally {
+            super.finalize();
+        }
+    }
 
     /**
      * Disposes of the underlying native Z3 object.