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:

 public class Thread7 {
     private Object xlock = new Object();

     public void sync_fun() {
         // synchronized (a1) {//synchronized只能是对象,基本类型不可以.
         synchronized (xlock) {
             int i = ;
             while (i-- > ) {
                 System.out
                         .println(Thread.currentThread().getName() + " : " + i);
                 try {
                     Thread.sleep();
                 } catch (InterruptedException ie) {
                 }
             }
         }
     }
     public void no_sync_fun() {
         int i = ;
         while (i-- > ) {
             System.out.println(Thread.currentThread().getName() + " : " + i);
             try {
                 Thread.sleep();
             } catch (InterruptedException ie) {
             }
         }
     }
     public static void main(String[] args) {
         final Thread7 t7 = new Thread7();
         Thread t1 = new Thread(new Runnable() {
             @Override
             public void run() {
                 t7.sync_fun();
             }
         }, "t1");
         Thread t2 = new Thread(new Runnable() {
             @Override
             public void run() {
                 t7.sync_fun();
             }
         }, "t2");
         Thread t3 = new Thread(new Runnable() {
             @Override
             public void run() {
                 t7.sync_fun();
             }
         }, "t3");
         Thread t4 = new Thread(new Runnable() {
             @Override
             public void run() {
                 t7.sync_fun();
             }
         }, "t4");
         Thread no_sync = new Thread(new Runnable() {
             @Override
             public void run() {
                 t7.no_sync_fun();
             }
         }, "no_sync");
         t1.start();
         t2.start();
         no_sync.start();
         t3.start();
         t4.start();
     }
 }

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