Java Thread join() 的用法

Java Thread中， join() 方法是让调用该方法的主线程执行run()时暂时卡住，等run()执行完成后， 主线程再调用执行join()后面的代码。示例：

1class ThreadTesterA implements Runnable {
2
3	private int counter;
4
5	@Override
6	public void run() {
7		while (counter <= 10) {
8			System.out.print("Counter = " + counter + " ");
9			counter++;
10		}
11		System.out.println();
12	}
13}
14
15class ThreadTesterB implements Runnable {
16
17	private int i;
18
19	@Override
20	public void run() {
21		while (i <= 10) {
22			System.out.print("i = " + i + " ");
23			i++;
24		}
25		System.out.println();
26	}
27}
28
29public class ThreadTester {
30	public static void main(String[] args) throws InterruptedException {
31		Thread t1 = new Thread(new ThreadTesterA());
32		Thread t2 = new Thread(new ThreadTesterB());
33		t1.start();
34		t1.join(); // wait t1 to be finished
35		t2.start();
36		t2.join(); // in this program, this may be removed
37	}
38}

如果去掉t1.join()这个语句过后， 输出的顺序是乱的， 加上这个语句后， 就会按照顺序输出，  从某种意义上说实现了同步。