有三个线程，a、b、c，a打印“T1”，b打印“T2”，c打印“T3”，a执行完后，b执行；b执行完后，c执行。如此循环100遍

有三个线程，a、b、c，a打印“T1”，b打印“T2”，c打印“T3”，a执行完后，b执行；b执行完后，c执行。如此循环100遍。

package com.company;

/**
 * 测试三个线程协同运行
 *
 * @Auther: xxx
 * @Date: Created In 2018/1/1 22:18
 * @Modified By:
 */
public class TestThread {
    public static void main(String[] args) {
        Thread1 t1 = new Thread1("T1");
        Thread1 t2 = new Thread1("T2");
        Thread1 t3 = new Thread1("T3");
        t1.setNotifySignalLight(t2.getSignalLight());
        t2.setNotifySignalLight(t3.getSignalLight());
        t3.setNotifySignalLight(t1.getSignalLight());
        t1.start();
        t2.start();
        t3.start();
        t1.getSignalLight().notifyThis();
    }
}

/**
 * 执行打印任务线程
 */
class Thread1 extends Thread {
    //当前线程的信号灯
    private SignalLight signalLight = new SignalLight();
    //需要打印的消息
    private String msg;

    /**
     * 当前线程的信号灯
     *
     * @return
     */
    public SignalLight getSignalLight() {
        return signalLight;
    }

    //当前线程需要指示其他线程的信号灯
    private SignalLight notifySignalLight = null;

    /**
     * 设置其他线程的信号灯
     * @param notifySignalLight
     */
    public void setNotifySignalLight(SignalLight notifySignalLight) {
        this.notifySignalLight = notifySignalLight;
    }

    /**
     * 构造函数
     * @param msg 打印的消息
     */
    public Thread1(String msg) {
        this.msg = msg;
    }

    /**
     * 线程的执行体
     */
    @Override
    public void run() {
        for (int i = 0; i < 100; i++) {
            this.signalLight.print(msg);
            this.notifySignalLight.notifyThis();
        }
    }
}

/**
 * 信号灯类
 */
class SignalLight {
    //是否打印消息，默认不打印，再线程外，发送消息打印
    private boolean isPass = false;

    /**
     * 打印消息
     * @param msg
     */
    public synchronized void print(String msg) {
        //如果isPass == false，则线程等待信号，才能执行
        if (!isPass) {
            try {
                this.wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        if (isPass)
            System.out.println(msg);
        this.isPass = false;
    }

    /**
     * 通知当前线程，可以执行
     */
    public synchronized void notifyThis() {
        this.isPass = true;
        this.notify();
    }
}