序

死锁在平时开发，尤其是多并发编程时是要避免，不过要自己刻意写个死锁还不一定容易，下面别人代码写一个

代码

public class DeadLock implements Runnable{    private int flag = 1;    private static final Object o1 = new Object();    private static final Object o2 = new Object();    public void setFlag(int flag) {        this.flag = flag;    }    @Override    public void run() {        if (flag == 1) {            synchronized (o1) {                System.out.println(Thread.currentThread().getName() + " o1");                try {                    Thread.sleep(800);                } catch (InterruptedException e) {                    e.printStackTrace();                }                synchronized (o2) {                    System.out.println(Thread.currentThread().getName() + " o2");                }            }        }        if (flag == 2) {            synchronized (o2) {                System.out.println(Thread.currentThread().getName() + " o2");                try {                    Thread.sleep(800);                } catch (InterruptedException e) {                    e.printStackTrace();                }                synchronized (o1) {                    System.out.println(Thread.currentThread().getName() + " o1");                }            }        }    }    public static void main(String[] args) {        DeadLock deadLock1 = new DeadLock();        DeadLock deadLock2 = new DeadLock();        deadLock1.setFlag(1);        Thread thread1= new Thread(deadLock1, "Thread1");        thread1.start();        deadLock2.setFlag(2);        Thread thread2= new Thread(deadLock2, "Thread2");        thread2.start();    }}

说明

o1、o2是static类型属于整个累，所以当定义deadLock1、deadLock2时是公用o1、o2的

deadLock1设置flag=1，先锁住o1，然后睡800ms，此时

deadLock2设置flag=2，先锁住o2，然后睡800ms

然后deadLock1开始锁o2,不过o2还被deadLock2锁着，只好等待。。。

此时deadLock1开始锁01，不过o1还被deadLock1锁着，只好等待。。。

相互等待造成死锁

结果

Thread1 o1Thread2 o2