Java多线程互斥访问变量

Java多线程互斥访问比较简单，在方法前面加上synchronize修饰则变为同步方法。下面是例子：

class WorkThread extends Thread{    private CourruptedData data = null ;    private int type = 0 ;    public WorkThread(CourruptedData _data,int _type){        data = _data ;        type = _type ;        super.start();    }    public void run(){        data.performWork(type);    }}public class CourruptedData {    protected static int display = 1 ;    protected static int change = 2 ;    private WorkThread slowWorker = null ;    private WorkThread fastWorker = null ;    private int number = 0 ;    public CourruptedData() {        number = 1 ;        slowWorker = new WorkThread(this,display);//-----------慢进程先启动;        fastWorker = new WorkThread(this,change);    }    /*     * 关键字为synchronized时，方法修饰为同步方法，     * 慢线程调用performWokr()时，休眠两秒；     * 此时，不允许第二个线程打断第一个线程；     * 等第一个线程执行完毕之后，第二个线程才能将number改为-1；     */    public synchronized void performWork(int type){        if (type == display)        {            System.out.println("Number before sleeping:" + number);            try{                slowWorker.sleep(2000);            }catch (InterruptedException ie){                System.out.println("Error : "+ie);            }            System.out.println("Number after working up:"+ number);        }        if (type == change)            number = -1 ;    }    public static void main(String args[])    {        CourruptedData test = new CourruptedData();    }}

程序运行结果为：

当去掉performWork()方法的 synchronized 修饰之后，程序运行结果为：