静态同步函数

 package com.RunnableDemo;

/**

 * 同步函数被静态修饰后，它使用是锁是该函数所属类的字节码文件对象：类名.class,该对象的类型是Class。

 * 

 * 静态进入内存时，内存中没有该类的对象，但一定有该类对应的字节码文件对象,这个对象是唯一的。

 * 

 * 

 * 

 * 

 * */

public class ThreadRunnable implements Runnable {

private static int Ticket = 1000;

boolean flag = true;

Object obj = new Object();

@Override

public void run() {

if (flag) {

while (true)

{

synchronized (ThreadRunnable.class)// 锁

{

if (Ticket > 0) {

try {

Thread.sleep(20);

} catch (InterruptedException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

System.out.println(Thread.currentThread().getName()

+ "__sale__" + Ticket--);

}

}

}

}

else {

while (true) {

show();

}

}

}

// 同步函数用的是所属对象的锁this

public static synchronized void show() {

while (true)

{

if (Ticket > 0) {

try {

Thread.sleep(20);

} catch (InterruptedException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

System.out.println(Thread.currentThread().getName()

+ "__show__" + Ticket--);

}

}

}

/**

* @param args

*/

public static void main(String[] args) {

ThreadRunnable t = new ThreadRunnable();

Thread t1 = new Thread(t);

Thread t2 = new Thread(t);

Thread t3 = new Thread(t);

Thread t4 = new Thread(t);

t1.start();

try {

Thread.sleep(10);

} catch (InterruptedException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

t.flag = false;

t2.start();

try {

Thread.sleep(10);

} catch (InterruptedException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

t3.start();

try {

Thread.sleep(10);

} catch (InterruptedException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

t.flag =true;

t4.start();

}

}