1. synchronized實現雙執行緒交替列印

class Print implements Runnable{
	static int i=0;
	static final int n=100;
	@Override
	public void run() {
		synchronized (this) {
			while (i < n) {
				System.out.println(i++ + Thread.currentThread().getName());
				notify();
				try {
					Thread.sleep(5);
					wait();
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		}
	}
}

public class Main {
	public static void main(String[] args){
		Print p=new Print();
		Thread t1=new Thread(p);
		Thread t2=new Thread(p);
		t1.setName("A====");
		t2.setName("B");
		t1.start();
		t2.start();
	}
}
 

2. 訊號量實現雙執行緒交替列印

public static void main(String[] args){
    final AtomicInteger i=new AtomicInteger(0);
    final int n=100;
    final Semaphore x1=new Semaphore(1);
    final Semaphore x2=new Semaphore(0);
    new Thread(()->{
        while (i.get() < n) {
            x1.acquireUninterruptibly();
            System.out.println(i.getAndIncrement()+":A=====");
            x2.release();
        }
    }).start();
    new Thread(()->{
        while (i.get() < n) {
            x2.acquireUninterruptibly();
            System.out.println(i.getAndIncrement()+":B");
            x1.release();
        }
    }).start();
}
 

3.ReentrantLock+Condition實現