package com.company;

import java.util.concurrent.locks.Condition;

import java.util.concurrent.locks.Lock;

import java.util.concurrent.locks.ReentrantLock;

/*

 * 编写一个程序，开启 3 个线程，这三个线程的 ID 分别为 A、B、C，每个线程将自己的 ID 在屏幕上打印 10 遍，要求输出的结果必须按顺序显示。

 *    如：ABCABCABC…… 依次递归

 */

public class TestABCAlternate {

    public static void main(String[] args) {

        AlternateDemo ad = new AlternateDemo();

        new Thread(() -> {

            for (int i = 1; i <= 10; i++) {

                ad.loopA(i);

            }

        }, "A").start();

        new Thread(() -> {

            for (int i = 1; i <= 10; i++) {

                ad.loopB(i);

            }

        }, "B").start();

        new Thread(() -> {

            for (int i = 1; i <= 10; i++) {

                ad.loopC(i);

            }

        }, "C").start();

    }

}

class AlternateDemo {

    private int number = 1; //当前正在执行线程的标记

    private Lock lock = new ReentrantLock();

    private Condition condition1 = lock.newCondition();

    private Condition condition2 = lock.newCondition();

    private Condition condition3 = lock.newCondition();

    /**

     * @param totalLoop : 循环第几轮

     */

    void loopA(int totalLoop) {

        lock.lock();

        try {

            //1. 判断

            if (number != 1) {

                condition1.await();

            }

            //2. 打印

            for (int i = 1; i <= 1; i++) {

                System.out.println(Thread.currentThread().getName() + "\t" + i + "\t" + totalLoop);

            }

            //3. 唤醒

            number = 2;

            condition2.signal();

        } catch (Exception e) {

            e.printStackTrace();

        } finally {

            lock.unlock();

        }

    }

    void loopB(int totalLoop) {

        lock.lock();

        try {

            //1. 判断

            if (number != 2) {

                condition2.await();

            }

            //2. 打印

            for (int i = 1; i <= 1; i++) {

                System.out.println(Thread.currentThread().getName() + "\t" + i + "\t" + totalLoop);

            }

            //3. 唤醒

            number = 3;

            condition3.signal();

        } catch (Exception e) {

            e.printStackTrace();

        } finally {

            lock.unlock();

        }

    }

    void loopC(int totalLoop) {

        lock.lock();

        try {

            //1. 判断

            if (number != 3) {

                condition3.await();

            }

            //2. 打印

            for (int i = 1; i <= 1; i++) {

                System.out.println(Thread.currentThread().getName() + "\t" + i + "\t" + totalLoop);

            }

            System.out.println("------------------");

            //3. 唤醒

            number = 1;

            condition1.signal();

        } catch (Exception e) {

            e.printStackTrace();

        } finally {

            lock.unlock();

        }

    }

}

A    1    1

B    1    1

C    1    1

------------------

A    1    2

B    1    2

C    1    2

------------------

A    1    3

B    1    3

C    1    3

------------------

A    1    4

B    1    4

C    1    4

------------------

A    1    5

B    1    5

C    1    5

------------------

A    1    6

B    1    6

C    1    6

------------------

A    1    7

B    1    7

C    1    7

------------------

A    1    8

B    1    8

C    1    8

------------------

A    1    9

B    1    9

C    1    9

------------------

A    1    10

B    1    10

C    1    10

------------------