多线程交替打印：A B C 循环

这是一个多线程任务中的：依次执行问题

方式一：LockSupport

package com.chstack.learning.concurrent.abc;

import java.util.concurrent.locks.LockSupport;

public class LockSuppABC {

    static Thread threadA, threadB, threadC;

    public static void print(String str, Thread next) {
        for (int i = 0; i < 3; i++) { // 打印100次
            LockSupport.park(); // 当前线程阻塞
            System.out.print(str);
            LockSupport.unpark(next); // 唤醒下一个线程
        }
    }

    public static void main(String[] args) {

        threadA = new Thread(() -> print("A\n", threadB));
        threadB = new Thread(() -> print("B\n", threadC));
        threadC = new Thread(() -> print("C\n", threadA));

        threadA.start();
        threadB.start();
        threadC.start();

        // 触发第一个线程（A）
        LockSupport.unpark(threadA);
    }
}

方式二：Semaphore

package com.chstack.learning.concurrent.abc;

import java.util.concurrent.Semaphore;

public class SemaphoreABC {

    public static void main(String[] args) {

        Semaphore semaphoreA = new Semaphore(1);
        Semaphore semaphoreB = new Semaphore(0);
        Semaphore semaphoreC = new Semaphore(0);

        int times = 3;

        new Thread(()->{
            for (int i = 0; i < times; i++) {
                try {
                    semaphoreA.acquire();
                    System.out.println("A");
                    semaphoreB.release();
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                }
            }
        }).start();

        new Thread(()->{
            for (int i = 0; i < times; i++) {
                try {
                    semaphoreB.acquire();
                    System.out.println("B");
                    semaphoreC.release();
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                }
            }
        }).start();

        new Thread(()->{
            for (int i = 0; i < times; i++) {
                try {
                    semaphoreC.acquire();
                    System.out.println("C");
                    semaphoreA.release();
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                }
            }
        }).start();
    }
}