import java.util.*;
//import java.util.concurrent.locks.LockSupport;
import java.util.concurrent.locks.LockSupport;
public class test {
   static Thread threadA, threadB, threadC;


    public static void main(String[] args) {
        threadA = new Thread(() -> {
//            for (int i = 0; i < 10; i++) {
                // 打印当前线程名称
//                System.out.print(Thread.currentThread().getName());
            System.out.print("A");

            // 唤醒下一个线程
                LockSupport.unpark(threadB);
                // 当前线程阻塞
                LockSupport.park();
//            }
        });
        threadB = new Thread(() -> {

                // 先阻塞等待被唤醒
                LockSupport.park();
                System.out.print(Thread.currentThread().getName());
                // 唤醒下一个线程
                LockSupport.unpark(threadC);

        }, "B");
        threadC = new Thread(() -> {

                // 先阻塞等待被唤醒
                LockSupport.park();
                System.out.print(Thread.currentThread().getName());
                // 唤醒下一个线程
                LockSupport.unpark(threadA);

        }, "C");
        threadA.start();
        threadB.start();
        threadC.start();
    }
}

使用信号量交替打印ABC（打印10次）

  static class Printer implements Runnable {
            private char letter;
            private Semaphore currentSemaphore;
            private Semaphore nextSemaphore;

            public Printer(char letter, Semaphore currentSemaphore, Semaphore nextSemaphore) {
                this.letter = letter;
                this.currentSemaphore = currentSemaphore;
                this.nextSemaphore = nextSemaphore;
            }

            @Override
            public void run() {
                for (int i = 0; i < 10; i++) {
                    try {
                        // 获取当前信号量的许可
                        currentSemaphore.acquire();
                        System.out.print(letter);
                        // 释放下一个信号量的许可
                        nextSemaphore.release();
                    } catch (InterruptedException e) {
                        Thread.currentThread().interrupt();
                    }
                }
            }
        }


    public static void main(String[] args) {

        Thread threadA = new Thread(new Printer('A', semaphoreA, semaphoreB));
        Thread threadB = new Thread(new Printer('B', semaphoreB, semaphoreC));
        Thread threadC = new Thread(new Printer('C', semaphoreC, semaphoreA));

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