java 多线程callable_JAVA语言之多线程编程之Runnable与Callable区别

本文主要向大家介绍了JAVA语言之多线程编程之Runnable与Callable区别，通过具体的内容向大家展示，希望对大家学习JAVA语言有所帮助。

Runnable

@FunctionalInterfacepublic interface Runnable {    /**     * When an object implementing interface Runnable is used     * to create a thread, starting the thread causes the object's     * run method to be called in that separately executing     * thread.     *

     * The general contract of the method run is that it may     * take any action whatsoever.     *     * @see     java.lang.Thread#run()     */    public abstract void run();}

Callable

@FunctionalInterfacepublic interface Callable {    /**     * Computes a result, or throws an exception if unable to do so.     *     * @return computed result     * @throws Exception if unable to compute a result     */    V call() throws Exception;}

相同点：1.都是接口，都能够实现多线程编程，都需要Thread.start()来启动线程。

不同点：1.Callable接口支持返回执行结果，此时需要调用FutureTask.get()方法实现，此方法会阻塞主线程直到获取‘将来’结果；当不调用此方法时，主线程不会阻塞！

Callable使用

/** * CallableImpl 简要描述 *

TODO:描述该类职责 

 * * @author ckmike * @version 1.0 * @date 18-12-6 下午8:53 * @copyright ckmike **/public class CallableImpl implements Callable {    private String accept;    public CallableImpl(String accept) {        this.accept = accept;    }    @Override    public String call() throws Exception {        // 休眠        TimeUnit.SECONDS.sleep(3);        return this.accept;    }    public static void main(String[] args) throws ExecutionException, InterruptedException {        Callable callable = new CallableImpl("my callable test!");        FutureTask task = new FutureTask<>(callable);        long beginTime = System.currentTimeMillis();        // 创建线程        new Thread(task).start();        // 调用get()阻塞主线程，反之，线程不会阻塞        String result = task.get();        long endTime = System.currentTimeMillis();        System.out.println("hello : " + result);        System.out.println("cast : " + (endTime - beginTime) / 1000 + " second!");    }}

Runnable使用

/** * RunnableImpl 简要描述 *

TODO:描述该类职责 

 * * @author ckmike * @version 1.0 * @date 18-12-6 下午9:03 * @copyright ckmike **/public class RunnableImpl implements Runnable {    public RunnableImpl(String accept) {        this.accept = accept;    }    private String accept;    @Override    public void run() {        // 线程阻塞 1 秒，此时有异常产生，只能在方法内部消化，无法上抛        try {            TimeUnit.SECONDS.sleep(1);        } catch (InterruptedException e) {            e.printStackTrace();        }        // 最终处理结果无法返回        System.out.println("hello : " + this.accept);    }    public static void main(String[] args) {        Runnable runnable = new RunnableImpl("my runable test!");        long beginTime = System.currentTimeMillis();        new Thread(runnable).start();        long endTime = System.currentTimeMillis();        System.out.println("cast : " + (endTime - beginTime) / 1000 + " second!");    }}

写这篇文章的原因是：面试时问道Runnable与Callable的区别，平时也就用Runnable比较多，基本上没有用过Callable，所以就挂了，哈哈哈，也总结给有需要的朋友。有知道Callable接口的使用场景吗？有的话可以留意分享给我吗？谢谢了！

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