/*　　死锁：常见情景之一：同步的嵌套。*/class Ticket implements Runnable {    private  int num = 100;    Object obj = new Object();    boolean flag = true;    public void run() {        if(flag) {            while(true) {                synchronized(obj) {                    show();                }            }                }                    else {                    while(true) {                this.show();            }                }                             }    public synchronized void show() {        synchronized(obj) {            if(num>0) {                try{Thread.sleep(10);}catch (InterruptedException e){}                                System.out.println(Thread.currentThread().getName()+".....sale...."+num--);            }        }    }}class DeadLockDemo {
    public static void main(String[] args) {        Ticket t = new Ticket();        Thread t1 = new Thread(t);        Thread t2 = new Thread(t);        t1.start();        try{Thread.sleep(10);}catch(InterruptedException e){}        t.flag = false;        t2.start();    }}