thread 死锁

public class DeadThread implements Runnable {

   private String flag;

    private Object lock1 = new Object();
 private Object lock2 = new Object();

    public void run() {
      if ("a".equals(flag)) {
          synchronized (lock1) {
               try {
                    Thread.sleep(5000);
              } catch (InterruptedException e) {
                   e.printStackTrace();
             }
                synchronized (lock2) {
                   System.out.println("lock1 调用 lock2");
                }
            }
        }

       if ("b".equals(flag)) {
          synchronized (lock2) {
               try {
                    Thread.sleep(5000);
              } catch (InterruptedException e) {
                   e.printStackTrace();
             }
                synchronized (lock1) {
                   System.out.println("lock2 调用 lock1");
                }
            }
        }
    }

   public void setFlag(String flag) {
       this.flag = flag;
    }
}

public class ThreadRunner {

    public static void main(String[] args) {
     DeadThread deadThread = new DeadThread();
        deadThread.setFlag("a");
     Thread thread1 = new Thread(deadThread);
     thread1.start();
     deadThread.setFlag("b");
     Thread thread2 = new Thread(deadThread);
     thread2.start();
 }
}