object not locked by thread before notify() 小例子

package com.vtc365.codec;

import com.vtc365.utils.ConfigureHelper;

public abstract class EncoderThread extends Thread {
    static int STOP=0;
    static int RUNNING=1;
    static int PAUSE=2;
    Integer status=STOP;
    public void run(){
        status=RUNNING;
        while(true){
            synchronized (status) {
                if(status==STOP)
                    break;
            }
            try {
                Thread.sleep(5000);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }

    public void stopThread(){
        synchronized (status) {
            status=STOP;
            status.notify();
        }
    }
}

当调用该类的stopThread方法时，系统会在notify报错，object not locked by thread before notify()；
百思不得其解，27行已经lock了啊。

仔细分析发现，27行的status，和29行的status已经不是一个对象了。