public class Deadlock {
    static class Friend {
        private final String name;

        public Friend(String name) {
            this.name = name;
        }

        public String getName() {
            return this.name;
        }

        public synchronized void bow(Friend bower) {
            System.out.format("%s 向  %s 鞠躬, %s 等待%s回应他的鞠躬", this.name, bower.getName(), this.name, bower.getName());
            System.out.println();
            bower.bowBack(this);
        }

        public synchronized void bowBack(Friend bower) {
            System.out.format("%s 回应  %s 的鞠躬", this.name, bower.getName());
            System.out.println();
        }
    }

    public static void main(String[] args) throws InterruptedException {
        final Friend alphonse = new Friend("A");
        final Friend gaston = new Friend("B");
        new Thread(new Runnable() {
            public void run() {
                alphonse.bow(gaston);
            }
        }).start();
        new Thread(new Runnable() {
            public void run() {
                gaston.bow(alphonse);
            }
        }).start();
    }
}