Java Thread join() 的用法

Java Thread中， join() 方法主要是让调用改方法的thread完成run方法里面的东西后， 在执行join()方法后面的代码。示例：

class ThreadTesterA implements Runnable {

    private int counter;

    @Override
    public void run() {
        while (counter <= 10) {
            System.out.print("Counter = " + counter + " ");
            counter++;
        }
        System.out.println();
    }
}

class ThreadTesterB implements Runnable {

    private int i;

    @Override
    public void run() {
        while (i <= 10) {
            System.out.print("i = " + i + " ");
            i++;
        }
        System.out.println();
    }
}

public class ThreadTester {
    public static void main(String[] args) throws InterruptedException {
        Thread t1 = new Thread(new ThreadTesterA());
        Thread t2 = new Thread(new ThreadTesterB());
        t1.start();
        t1.join(); // wait t1 to be finished
        t2.start();
        t2.join(); // in this program, this may be removed
    }
}

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

转自：http://auguslee.iteye.com/blog/1292203