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
时间： 2024-07-30 13:52:52