public class Test{

final Object lockA = new Object();
final Object lockB = new Object();

public static void main(String[] args) {
        Test demo = new Test();
demo.startLock();
}

public void startLock(){
ThreadA a= new ThreadA(lockA,lockB);
ThreadB b= new ThreadB(lockA,lockB);

//start threads
a.start();
b.start();
}

}

class ThreadA extends Thread{

private Object lockA = null;
private Object lockB = null;

public ThreadA(Object a, Object b){
this.lockA = a;
this.lockB = b;
}

public void run() {
synchronized (lockA) {
System.out.println("*** Thead A: ***: Lock A" );
try {
sleep(200);
} catch (InterruptedException e) {
e.printStackTrace();
}
synchronized (lockB) {
System.out.println("*** Thead A: ***: Lock B" );
}
}

System.out.println("*** Thead A: ***: Finished" );
}

}

class ThreadB extends Thread{

private Object lockA = null;
private Object lockB = null;

public ThreadB(Object a, Object b){
this.lockA = a;
this.lockB = b;
}
public void run() {
synchronized (lockB) {
System.out.println("*** Thead B: ***: Lock B" );
try {
sleep(200);
} catch (InterruptedException e) {
e.printStackTrace();
}
synchronized (lockA) {
System.out.println("***** Thead B: *****: Lock A" );
}
}       

System.out.println("***** Thead B: *****: Finished" );
}

}

这是一死锁线程?  怎样才能避免死锁的发生？

1. package TestJava;
   
2. 
   
3. public class Test {
   
4. 
   
5.         final Object lockA = new Object();
   
6.         final Object lockB = new Object();
   
7. 
   
8.         public static void main(String[] args) {
   
9.                 Test demo = new Test();
   
10.                 demo.startLock();
    
11.         }
    
12. 
    
13.         public void startLock() {
    
14.                 ThreadA a = new ThreadA(lockA, lockB);
    
15.                 ThreadB b = new ThreadB(lockA, lockB);
    
16. 
    
17.                 // start threads
    
18.                 a.start();
    
19.                 b.start();
    
20.         }
    
21. 
    
22. }
    
23. 
    
24. class ThreadA extends Thread {
    
25. 
    
26.         private Object lockA = null;
    
27.         private Object lockB = null;
    
28. 
    
29.         public ThreadA(Object a, Object b) {
    
30.                 this.lockA = a;
    
31.                 this.lockB = b;
    
32.         }
    
33. 
    
34.         public void run() {
    
35.                 synchronized (lockA) {
    
36.                         System.out.println("*** Thead A: ***: Lock A");
    
37.                         try {
    
38.                                 sleep(200);
    
39.                         } catch (InterruptedException e) {
    
40.                                 e.printStackTrace();
    
41.                         }
    
42.                 }
    
43.                 synchronized (lockB) {
    
44.                         System.out.println("*** Thead A: ***: Lock B");
    
45.                 }
    
46.                 System.out.println("*** Thead A: ***: Finished");
    
47.         }
    
48. 
    
49. }
    
50. 
    
51. class ThreadB extends Thread {
    
52. 
    
53.         private Object lockA = null;
    
54.         private Object lockB = null;
    
55. 
    
56.         public ThreadB(Object a, Object b) {
    
57.                 this.lockA = a;
    
58.                 this.lockB = b;
    
59.         }
    
60. 
    
61.         public void run() {
    
62.                 synchronized (lockB) {
    
63.                         System.out.println("*** Thead B: ***: Lock B");
    
64.                         try {
    
65.                                 sleep(200);
    
66.                         } catch (InterruptedException e) {
    
67.                                 e.printStackTrace();
    
68.                         }
    
69.                 }
    
70.                 synchronized (lockA) {
    
71.                         System.out.println("***** Thead B: *****: Lock A");
    
72.                 }
    
73.                 System.out.println("***** Thead B: *****: Finished");
    
74.         }
    
75. 
    
76. }
    

复制代码

改成这样就不会死锁了