线程抢答（2021-12-03）

  要求3个线程进行抢答，并返回抢答结果。

package ThreadDemo;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;

class Responder implements Callable<String>{
	private boolean flag = true;	//规定true表示还能抢答，false表示抢答完成
	
	public String call(){
		synchronized (this) {
			if(flag==true) {
				this.flag = false;
				return Thread.currentThread().getName()+"  抢答成功！！！";
			}
			else {
				return Thread.currentThread().getName()+"  抢答失败。";
			}
		}
	}
}

public class Main {
	public static void main(String[] args) throws InterruptedException, ExecutionException {
		Responder res = new Responder();
		FutureTask<String> taskA = new FutureTask<String>(res);
		FutureTask<String> taskB = new FutureTask<String>(res);
		FutureTask<String> taskC = new FutureTask<String>(res);
		new Thread(taskA,"抢答选手A").start();		
		new Thread(taskB,"抢答选手B").start();
		new Thread(taskC,"抢答选手C").start();		
		System.out.println(taskA.get());
		System.out.println(taskB.get());
		System.out.println(taskC.get());
	}
}