synchronized(3)修饰语句块之：synchronized(一般对象)

synchronized(一般对象)

　　一次只有一个线程进入该代码块.此时,线程获得的是成员锁.例如:

 1 public class Thread7 {
 2     private Object xlock = new Object();
 3 
 4     public void sync_fun() {
 5         // synchronized (a1) {//synchronized只能是对象,基本类型不可以.
 6         synchronized (xlock) {
 7             int i = 5;
 8             while (i-- > 0) {
 9                 System.out
10                         .println(Thread.currentThread().getName() + " : " + i);
11                 try {
12                     Thread.sleep(500);
13                 } catch (InterruptedException ie) {
14                 }
15             }
16         }
17     }
18     public void no_sync_fun() {
19         int i = 5;
20         while (i-- > 0) {
21             System.out.println(Thread.currentThread().getName() + " : " + i);
22             try {
23                 Thread.sleep(500);
24             } catch (InterruptedException ie) {
25             }
26         }
27     }
28     public static void main(String[] args) {
29         final Thread7 t7 = new Thread7();
30         Thread t1 = new Thread(new Runnable() {
31             @Override
32             public void run() {
33                 t7.sync_fun();
34             }
35         }, "t1");
36         Thread t2 = new Thread(new Runnable() {
37             @Override
38             public void run() {
39                 t7.sync_fun();
40             }
41         }, "t2");
42         Thread t3 = new Thread(new Runnable() {
43             @Override
44             public void run() {
45                 t7.sync_fun();
46             }
47         }, "t3");
48         Thread t4 = new Thread(new Runnable() {
49             @Override
50             public void run() {
51                 t7.sync_fun();
52             }
53         }, "t4");
54         Thread no_sync = new Thread(new Runnable() {
55             @Override
56             public void run() {
57                 t7.no_sync_fun();
58             }
59         }, "no_sync");
60         t1.start();
61         t2.start();
62         no_sync.start();
63         t3.start();
64         t4.start();
65     }
66 }

结果:

t1 : 4
no_sync : 4
t1 : 3
no_sync : 3
t1 : 2
no_sync : 2
t1 : 1
no_sync : 1
t1 : 0
no_sync : 0
t4 : 4
t4 : 3
t4 : 2
t4 : 1
t4 : 0
t3 : 4
t3 : 3
t3 : 2
t3 : 1
t3 : 0
t2 : 4
t2 : 3
t2 : 2
t2 : 1
t2 : 0