一、使用LockSupport

public class T4 {
    static Thread t1 = null, t2 = null;

    public static void main(String[] args) {
        char[] number = "123456789".toCharArray();
        char[] chars = "ABCDEFGHI".toCharArray();
        t1 = new Thread(new Runnable() {
            @Override
            public void run() {
                for (char c : number) {
                    System.out.print(c);
                    LockSupport.unpark(t2); //唤醒当前线程
                    LockSupport.park();
                }
            }
        });
        t2 = new Thread(new Runnable() {
            @Override
            public void run() {
                for (char c : chars) {
                    LockSupport.park(); //阻塞当前线程 确保t1先输出
                    System.out.print(c);
                    LockSupport.unpark(t1);
                }
            }
        });
        t1.start();
        t2.start();
    }

}

二、synchronized，notify，wait，

public class T3 {
    static Thread t1 = null, t2 = null;
    //确保数字先运行
    private static CountDownLatch latch = new CountDownLatch(1);
    public static void main(String[] args) {
        Object o = new Object();
        char[] number = "123456789".toCharArray();
        char[] chars = "ABCDEFGHI".toCharArray();
        t1 = new Thread(new Runnable() {
            @Override
            public void run() {
                synchronized (o) {
                    for (char c : number) {
                        System.out.print(c);
                        latch.countDown();
                        try {
                            //顺序不可以改变
                            o.notify();//只能在持有锁的情况下使用，随机唤醒一个线程
                            o.wait();//持有这把锁的线程进入对待队列且释放这把锁
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    //如果不唤醒，就会导致程序没有办法停止,原因是:总户有一个线程在阻塞状态
                    o.notify();
                }
            }
        }, "t1");
        t2 = new Thread(new Runnable() {
            @Override
            public void run() {
                synchronized (o) {
                    try {
                        latch.await();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    for (char c : chars) {
                        System.out.print(c);
                        try {
                            o.notify();
                            o.wait();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    o.notify();
                }
            }
        }, "t2");
        t1.start();
        t2.start();
    }
}