(原)测试 Java中Synchronized锁定对象的用法

今天再android_serial_port中看到了关键字 synchronized;因为刚好在学java和android，所以就查了一下它的用法：

于是把代码中的一小段代码拿了出来，做了一下修改，测试了下，结果出现的情况：

public class syncThreadDemo {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        /*测试1*/
//        Account account = new Account("zhang san", 10000.0f);
//        AccountOperator accountOperator = new AccountOperator(account);
//
//        final int THREAD_NUM = 5;
//        Thread threads[] = new Thread[THREAD_NUM];
//        for (int i = 0; i < THREAD_NUM; i ++) {
//           threads[i] = new Thread(accountOperator, "Thread" + i);
//           threads[i].start();
//        }
        
        /*测试2*/
        
        Thread thread1=new Thread(new syncThreadDemo().new SendingThread("send1"),"thread1");
        thread1.start();
        Thread thread2=new Thread(new syncThreadDemo().new ReceiveThread("recv1"),"thread2");
        thread2.start();
        
    }
    /*创建一个内部类来测试synchronized锁定一个对象*/
    static Object mByteReceivedBackSemaphore = new Object();

    private class SendingThread implements Runnable{
        private int i=0;
        private String name;
        //创建一个构造函数
        public SendingThread(String strName) {
            // TODO Auto-generated constructor stub
            this.name=strName;
        }
        
        @Override
        public void run(){
            while (i<10) {
                synchronized (mByteReceivedBackSemaphore) {
                    try {
                        // Wait for 100ms before sending next byte, or as soon as
                        // the sent byte has been read back.
                        System.out.println(Thread.currentThread().getName()+": wait");
                        mByteReceivedBackSemaphore.wait(100);
                        i++;
                        System.out.println(Thread.currentThread().getName()+":"+i);
                    } 
                    catch (Exception e) {
                        // TODO: handle exception
                    }    
                }
            }
        }
     }

     private class ReceiveThread implements Runnable{
        private int j=0;
        private String name;
        
        public ReceiveThread(String strName) {
            // TODO Auto-generated constructor stub
            this.name=strName;
        }
        
        @Override
        public void run(){
            while(j<10){
                synchronized(mByteReceivedBackSemaphore){
                    System.out.println(Thread.currentThread().getName()+": notify");
                    mByteReceivedBackSemaphore.notify();    
                    j++;
                    System.out.println(Thread.currentThread().getName()+":"+j);
                }
            }
        }
     }
}

测试结果：

thread1: wait
thread2: notify
thread2:1
thread2: notify
thread2:2
thread2: notify
thread2:3
thread2: notify
thread2:4
thread2: notify
thread2:5
thread2: notify
thread2:6
thread2: notify
thread2:7
thread2: notify
thread2:8
thread2: notify
thread2:9
thread2: notify
thread2:10
thread1:1
thread1: wait
thread1:2
thread1: wait
thread1:3
thread1: wait
thread1:4
thread1: wait
thread1:5
thread1: wait
thread1:6
thread1: wait
thread1:7
thread1: wait
thread1:8
thread1: wait
thread1:9
thread1: wait
thread1:10