（一）线程管理_5---等待线程终止

等待线程终止

在有的时候，须要等待一个线程执行完后才能继续执行后面的程序；好比资源的加载，只有当加载完全部的资源后，在继续执行业务逻辑部分；那么Thread类的join方法，Thread.join()就起这个做用； 当一个线程使用一个线程对象调用了join()方法，那么这个线程对象将会被挂起，直到这个线程对象执行完毕后，调用线程才会继续执行；

动手实现

public class ResourceLoader implements Runnable {
    //模拟资源加载
    @Override
    public void run() {
        System.out.printf("Beginning data sources loadding:%s\n", new Date());
        try {
            TimeUnit.SECONDS.sleep(4);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.printf("Data source loading has finished:%s\n", new Date());
    }

    public static void main(String[] args) {
        Thread thread1 = new Thread(new ResourceLoader(), "localResourceLoader");
        Thread thread2 = new Thread(new ResourceLoader(), "remoteResourceLoader");
        thread1.start();
        thread2.start();
        //主线程等待资源加载完毕
        try {
            thread1.join();
            thread2.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.printf("Main:Resource has been loaded:%s\n", new Date());

    }
}

一次运行结果：

Beginning data sources loadding:Fri Oct 31 00:09:37 CST 2014
Beginning data sources loadding:Fri Oct 31 00:09:37 CST 2014
Data source loading has finished:Fri Oct 31 00:09:41 CST 2014
Data source loading has finished:Fri Oct 31 00:09:41 CST 2014
Main:Resource has been loaded:Fri Oct 31 00:09:41 CST 2014

要点

Java提供了两个方法

1. join(long milliseconds)
2. join(long milliseconds,long nanos)

第二个方法接受两个参数，毫秒，纳秒

join方法是Thread类非静态方法