ABC三个线程顺序执行（简单实现）

需求：3个线程 输出ABC ------> ABCABCABC。。。。。此类型

 

1、 使用线程池 将所有线程放入一个队列 ，保证顺序输出

public class ThreeThread {
    
    public static void main(String[] args) throws InterruptedException {

        //用线程池来实现 ，3个线程加入线程池
        ExecutorService pool = Executors.newSingleThreadExecutor();

        for (int i = 0; i < 10; i++) {
            pool.submit(()-> System.out.println("AAAAAA"));
            pool.submit(()-> System.out.println("BBBBBB"));
            pool.submit(()-> System.out.println("CCCCCC"));
        }
        pool.shutdown();

    }

}

2、使用 wait(), synchronized(同步锁)   轮询机制 到谁了 谁输出

public class ThreeThread {
    
    public static void main(String[] args) throws InterruptedException {
        Param param = new Param();//A开始打印
        new Thread(new Letter(param, "A", 0)).start();
        new Thread(new Letter(param, "B", 1)).start();
        new Thread(new Letter(param, "C", 2)).start();
    }
    
}

class Letter implements Runnable {

    private Param param;
    private String name;
    private int process;

    Letter(Param param, String name, int process) {
        this.param = param;
        this.name = name;
        this.process = process;
    }

    @Override
    public void run() {
        synchronized (param) {

            for (int i = 0; i < 10; i++) {
                int state = param.getState();
                while (state != process) {
                    try {
                        param.wait();//进入阻塞状态，释放该param对象 锁
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    state = param.getState();//再一次的获取最新的状态
                }

                System.out.println("----- " + name + " -----");
                param.setState(++state % 3);//设置状态
                param.notifyAll();//释放其他的2个阻塞状态
            }
        }

    }
}

// 为了同步取值
class Param {
    //状态 0 -> A 启动
    private int state = 0;

    public int getState() { return this.state; }

    public void setState(int state) { this.state = state; }
}