多线程返回值问题

多线程返回值问题？

import java.util.concurrent.Callable;

/**

* 线程类，需要返回值的 ，实现Callable接口

* @author xhc

*

*/

@SuppressWarnings("rawtypes")

public class MyThread implements Callable{

@SuppressWarnings("static-access")

@Override

public Object call() throws Exception {

Thread.currentThread().sleep(1000);//睡眠一秒

return Thread.currentThread().getName();

}

}

测试类：

package com.xjiuge.test;

import java.util.ArrayList;

import java.util.List;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.Future;

public class App {

//建立线程池

static ExecutorService pool = Executors.newCachedThreadPool();

@SuppressWarnings("unchecked")

public static void main(String[] args) {

//存放future的集合

List> list = new ArrayList<>();

long st = System.currentTimeMillis();//开始时间

//循环5次，开启5个线程

for (int i = 0; i < 5; i++) {

//获取线程类返回的值，用future接收

Future future = pool.submit(new MyThread());

//将future放入list

list.add(future);

}

try {

//遍历list读取future中的值

for (Future future : list) {

while(true) {

//判断线程操作是否执行完毕，并且操作没有被取消掉

if(future.isDone() && !future.isCancelled()) {

//调用get方法获取返回值

String result = future.get().toString();

System.out.println(result);

break;

}

}

}

} catch (Exception e) {

e.printStackTrace();

}

long et = System.currentTimeMillis();//结束时间

System.out.println("总耗时：" + (et - st) + "ms");

}

}

打印结果：

pool-1-thread-1

pool-1-thread-2

pool-1-thread-3

pool-1-thread-4

pool-1-thread-5

总耗时：1004ms