java：synchronized 同步代码块

synchronized(同步对象){
需要同步的代码；
}

class MyThread implements Runnable
{
    int i = 100;
    public void run(){
        while(true){    //并不是锁止状态，t1，t2同时进入
            System.out.println("-------------"+Thread.currentThread().getName());
            synchronized(this){        //如t1锁住，就算t2抢到cpu也进不去
                System.out.println(Thread.currentThread().getName() + i);
                i--;
                if(i<0){
                break;
                }
            }
        }
    }
}

class Test
{
    public static void main(String args[]){
        MyThread myThread = new MyThread();
        //生成两个Thread对象，共用一个线程体
        Thread t1 = new Thread(myThread);
        Thread t2 = new Thread(myThread);

        t1.setName("线程a");
        t2.setName("线程b");
        t1.start();
        t2.start();
    }
}