手搓代码

两个线程交替打印 A B，一共打印

信号量

public class Main {
    final static Semaphore semaphoreA = new Semaphore(1);
    final static Semaphore semaphoreB = new Semaphore(0);
    
    public static void main(String[] args) {
        Thread threadA = new Thread(() -> {
            try {
                for (int i = 0; i < 10; i++) {
                    semaphoreA.acquire(1);
                    System.out.println("A");
                    semaphoreB.release();
                }
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        });

        Thread threadB = new Thread(() -> {
            try {
                for (int i = 0; i < 10; i++) {
                    semaphoreB.acquire(1);
                    System.out.println("B");
                    semaphoreA.release();
                }
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        });

        threadA.start();
        threadB.start();
        threadA.join();
        threadB.join();
    }
}