/* * Copyright (C) 2011 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import java.lang.reflect.*; import java.util.Arrays; class NarrowingTest { interface I1 { public Object foo(); } interface I2 extends I1 { // Note that this method declaration narrows the return type. @Override public String foo(); } public static void main(String[] args) { I2 proxy = (I2) Proxy.newProxyInstance(NarrowingTest.class.getClassLoader(), new Class<?>[] { I2.class }, new InvocationHandler() { int count = 0; @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { System.out.println("Invocation of " + method); if (count == 0) { count++; return "hello"; } else { return Integer.valueOf(1); } } }); Main.registerProxyClassName(proxy.getClass().getCanonicalName()); Method[] methods = proxy.getClass().getDeclaredMethods(); System.out.println("Proxy methods: " + Main.replaceProxyClassNamesForOutput(Arrays.deepToString(methods))); System.out.println("Invoking foo using I2 type: " + proxy.foo()); I1 proxyAsParent = proxy; System.out.println("Invoking foo using I1 type: " + proxyAsParent.foo()); try { proxy.foo(); System.out.println("Didn't get expected exception"); } catch (ClassCastException e) { // With an I2 invocation returning an integer is an exception. System.out.println("Got expected exception"); } System.out.println("Proxy narrowed invocation return type passed"); } }