SummerVocation_Learning--java的线程死锁

 public class Test_DeadLock implements Runnable {

     public int flag = ;
     static Object o1 = new Object(),o2 = new Object();
     public void run() {
         System.out.println("flag= " + flag);
         if (flag == ) {
             synchronized (o1) {  //o1锁定
                 try {
                     Thread.sleep();
                 } catch (Exception e) {
                     e.printStackTrace();
                 }
             synchronized (o2) { //只要再锁定o2，就能打印出1.
                 System.out.println(""); //但是o2被另一个线程锁定了，所以打印不出1.
                 }
             }
         }
         if (flag == ) {
             synchronized (o2) { //锁定o2
                 try {
                     Thread.sleep();
                 } catch (Exception e) {
                     e.printStackTrace();
                 }
             synchronized (o1) {  //只要再等待锁定o1，就能打印出0.
                     System.out.println(""); //但是o1另一个线程锁定，无法执行。两个线程被锁死，谁都无法完成执行。
                 }
             }
         }
     }

     public static void main(String[] args) {
         Test_DeadLock t1 = new Test_DeadLock();
         Test_DeadLock t2 = new Test_DeadLock();
         t1.flag = ;
         t2.flag = ;
         Thread t11 = new Thread(t1);
         Thread t21 = new Thread(t2);
         t11.start(); t21.start();

     }
     /*
      * flag= 1
        flag= 0
                 两个线程产生死锁，synchronized的输出语句未被执行。
      */

 }