Java.lang.ClassCastException: $Proxy0 ??

Question

hello,
i'm having problems with this code, any help is always welcome
when i execute code from main(), i get this error:
Exception in thread "main" java.lang.ClassCastException: $Proxy0
at es.pruebas.Main.main(Main.java:14)
main.java
main()
     13 PersonasBDE b = new PersonasBDE();
     14 PersonasBDE p = (PersonasBDE)TransactionWrapper.decorate(b);
TransactionWrapper.java
public static Object decorate(PersonasBDE delegate)
ClassLoader cLoader = delegate.getClass().getClassLoader( );
Class[] interfaces = delegate.getClass().getInterfaces( );
XAWrapperHandler xa = new XAWrapperHandler(delegate);
Object o = Proxy.newProxyInstance(cLoader, interfaces, xa);
return o;
(inner class of TransactionWrapper)
static final class XAWrapperHandler implements InvocationHandler
private final PersonasBDE delegate;
XAWrapperHandler(PersonasBDE delegate)
// Cache the wrapped delegate, so we can pass method invocations
// to it.
this.delegate = delegate;
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable
return null;
the more surprising is that the error is not in constructor from TransactionWrapper, nor in method invoke! what can be the problem?
sorry for the messy code, but i can't find the problem...

Answer 1

You are trying to cast an Object to PersonasBDE, when that object is not an instance of PersonasBDE. Is PersonasBDE a class or an interface? If it is a class, then you cannot create a Proxy that is an instance of that class. All proxy classes you created extend Proxy and implement all the methods you specify. If PersonasBDE is an interface, then you must include it in the list of interfaces that you specify. So, to word this a different way:
The object you get from the call to newProxyInstance() can only be cast to either Proxy or one of the interface types you pass to the method.