Java: MultiThread

wait_notify.java

public class MultiThread {
	public static void main(String[] args) {
		new Thread(new Thread1()).start();
		try {
			Thread.sleep(10);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		new Thread(new Thread2()).start();		
	}
	

	private static class Thread1 implements Runnable
	{

		@Override
		public void run() {
			// TODO Auto-generated method stub
//由于这里的Thread1和下面的Thread2内部run方法要用同一对象作为监视器，我们这里不能用this，因为在Thread2里面的this和这个Thread1的this不是同一个对象。我们用MultiThread.class这个字节码对象，当前虚拟机里引用这个变量时，指向的都是同一个对象。
			synchronized (MultiThread.class) {

				System.out.println("enter thread1...");
				
				System.out.println("thread1 is waiting");
				try {
			//释放锁有两种方式，第一种方式是程序自然离开监视器的范围，也就是离开了synchronized关键字管辖的代码范围，另一种方式就是在synchronized关键字管辖的代码内部调用监视器对象的wait方法。这里，使用wait方法释放锁。
					MultiThread.class.wait();
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
				
				System.out.println("thread1 is going on...");
				System.out.println("thread1 is being over!");			
			}
		}
		
	}
	
	private static class Thread2 implements Runnable
	{

		@Override
		public void run() {
			// TODO Auto-generated method stub
			synchronized (MultiThread.class) {
			
				System.out.println("enter thread2...");
				
				System.out.println("thread2 notify other thread can release wait status..");
//由于notify方法并不释放锁， 即使thread2调用下面的sleep方法休息了10毫秒，但thread1仍然不会执行，因为thread2没有释放锁，所以Thread1无法得不到锁。

				MultiThread.class.notify();
				
				System.out.println("thread2 is sleeping ten millisecond...");
				try {
					Thread.sleep(10);
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
				
				System.out.println("thread2 is going on...");
				System.out.println("thread2 is being over!");
				
			}
		}
		
	}	

}