线程的同步

线程的同步：

public class TestSync implements Runnable{
	Timer timer = new Timer();
	public static void main(String[] args) {
		TestSync test = new TestSync();
		Thread t1 = new Thread(test);
		Thread t2 = new Thread(test);
		t1.setName("t1");
		t2.setName("t2");
		t1.start();
		t2.start();
	}

	public void run() {
		timer.add(Thread.currentThread().getName());
	}
}

class Timer{
	private static int num = 0;
	public void add(String name){
//如果不加synchronized，那么打印出的都是“你是第2个访问的人”
		synchronized (this) {
			num ++;
			try {
				Thread.sleep(1);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
			System.out.println(name + ": 你是第" + num + "个访问的人");
		}
	}
}

当然，也可以在void add前加synchronized，这样写起来简单点