ArrayList既然继承自AbstractList抽象类，而A

package example;

import java.io.Serializable;
import java.util.Arrays;

public class Test {

 public static interface MyInterface {
  void foo();
 }

 public static class BaseClass implements MyInterface, Cloneable, Serializable {

  @Override
  public void foo() {
   System.out.println("BaseClass.foo");
  }
 }

 public static class Class1 extends BaseClass {

  @Override
  public void foo() {
   super.foo();
   System.out.println("Class1.foo");
  }
 }

 static class Class2 extends BaseClass implements MyInterface, Cloneable,
   Serializable {

  @Override
  public void foo() {
   super.foo();
   System.out.println("Class2.foo");
  }
 }

 public static void main(String[] args) {

  showInterfacesFor(BaseClass.class);
  showInterfacesFor(Class1.class);
  showInterfacesFor(Class2.class);
 }

 private static void showInterfacesFor(Class<?> clazz) {
  System.out.printf("%s --> %s\n", clazz, Arrays.toString(clazz
    .getInterfaces()));
 }
}

输出：

class example.Test$BaseClass --> [interface example.Test$MyInterface, interface java.lang.Cloneable, interface java.io.Serializable]
class example.Test$Class1 --> []
class example.Test$Class2 --> [interface example.Test$MyInterface, interface java.lang.Cloneable, interface java.io.Serializable]

Class1没有定义明确的接口，因此Class#getInterfaces()不包括那些接口，而Class2直接实现了该接口。

package example;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

import example.Test.BaseClass;
import example.Test.Class1;
import example.Test.Class2;

public class Test2 extends Test {

 public static void main(String[] args) {

  MyInterface c1 = new Class1();
  MyInterface c2 = new Class2();

  // Note the order...
  MyInterface proxy2 = createProxy(c2);
  proxy2.foo();

  // This fails with an unchecked exception
  MyInterface proxy1 = createProxy(c1);
  proxy1.foo();
 }

 private static <T> T createProxy(final T obj) {

  final InvocationHandler handler = new InvocationHandler() {

   @Override
   public Object invoke(Object proxy, Method method, Object[] args)
     throws Throwable {
    System.out.printf("About to call %s() on %s\n", method
      .getName(), obj);
    return method.invoke(obj, args);
   }
  };

  return (T) Proxy.newProxyInstance(obj.getClass().getClassLoader(), obj
    .getClass().getInterfaces(), handler);
 }
}

虽然Class1确实隐式实现了MyInterface，但是创建的代理没有实现，所以报错。
输出：

About to call foo() on example.Test$Class2@578ceb
BaseClass.foo
Class2.foo
Exception in thread "main" java.lang.ClassCastException: $Proxy1 cannot be cast to example.Test$MyInterface
 at example.Test2.main(Test2.java:23)