java 接口可以继承多个接口
/* * %W% %E% * * Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved. * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */package java.util.concurrent;/** * A {@link Future} that is {@link Runnable}. Successful execution of * the <tt>run</tt> method causes completion of the <tt>Future</tt> * and allows access to its results. * @see FutureTask * @see Executor * @since 1.6 * @author Doug Lea * @param <V> The result type returned by this Future's <tt>get</tt> method */public interface RunnableFuture<V> extends Runnable, Future<V> { /** * Sets this Future to the result of its computation * unless it has been cancelled. */ void run();}