转自：JAVA 笔记 Callable 与 FutureTask:有返回值的多线程
常用的Thread类在run方法执行完之后是没有返回值的，要实现子线程完成任务后返回值给主线程需要借助第三方转存。Callable接口则提供了一种有返回值的多线程实现方法。下面以一个简单的地主、监工和长工的例子展示这种接口的用法。
长工类：
长工类实现了Callable接口，线程运行完成后返回一个Integer值。
package com.lk.C; import java.util.concurrent.Callable; public class Changgong implements Callable<Integer>{ //泛型限制了重写方法的返回值类型 private int hours=12; private int amount; @Override public Integer call() throws Exception { while(hours>0){ System.out.println("I'm working......"); amount ++; hours--; Thread.sleep(1000); } return amount; } }
地主：主进程
监工：FutureTask
package com.lk.C; import java.util.concurrent.ExecutionException; import java.util.concurrent.FutureTask; public class Dizhu { public static void main(String args[]){ Changgong worker = new Changgong(); FutureTask<Integer> jiangong = new FutureTask<Integer>(worker); new Thread(jiangong).start(); while(!jiangong.isDone()){ try { System.out.println("看长工做完了没..."); Thread.sleep(1000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } int amount; try { amount = jiangong.get(); System.out.println("工作做完了,上交了"+amount); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ExecutionException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
I'm working...... 看长工做完了没... I'm working...... 看长工做完了没... 看长工做完了没... I'm working...... 看长工做完了没... I'm working...... I'm working...... 看长工做完了没... I'm working...... 看长工做完了没... 看长工做完了没... I'm working...... I'm working...... 看长工做完了没... 看长工做完了没... I'm working...... I'm working...... 看长工做完了没... I'm working...... 看长工做完了没... 看长工做完了没... I'm working...... 看长工做完了没... 工作做完了,上交了12