线程的join方法练习

如果一个线程A(比如主线程)调用了另一个线程B(一个子线程)的join方法,主线程会等待调用join方法的子线程执行结束后再继续执行,上代码

package cn.cncc.demo;

public class TestJoin {
	//main线程就是个引导/启动程序,启动后如果没它什么事情它就先结束了
	public static void main(String[] args) {
		
		String threadName = Thread.currentThread().getName();   
		System.out.println(threadName + " start.");   
		
		PrepareWorkThread pt = new PrepareWorkThread("准备上班");
		PreparebBreakfast pb = new PreparebBreakfast("做早饭");
		pt.setPb(pb);
		pt.start();
		try {
			//加上这句,是让main线程等待pt线程执行完再往下走
			pt.join();
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		System.out.println(threadName + " end.");   

	}

}
/**
 * 准备上班线程
 * 起床,洗簌,然后吃早饭,去上班
 * 另起一个线程做早饭
 * @author root
 *
 */
class PrepareWorkThread extends Thread{
	
	PreparebBreakfast pb;
	
	public PrepareWorkThread(String string) {
		super(string);
	}

	public void setPb(PreparebBreakfast pb) {
		this.pb = pb;
	}
	public void run() {
		System.out.println("起床...............");
		System.out.println("通知佣人去做早饭.......");
		//启动做早饭线程
		pb.start();
		for(int i = 0;i<5;i++){
			
			System.out.println("洗簌..............." +i);
			try {
				Thread.sleep(1000);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
		System.out.println("洗簌结束...............");
		try {
			System.out.println("等待早饭做好..........");
			//等待做早饭线程执行完成,此时当前这个线程处于等待状态
			pb.join();
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		System.out.println("吃早饭..............");
		System.out.println("上班去了.............");
	}
	
}
class PreparebBreakfast extends Thread{
	public PreparebBreakfast(String name) {
		super(name);
	}
	@Override
	public void run() {
		for(int i = 0;i<10;i++){
			System.out.println("正在做早饭........." + i);
			try {
				Thread.sleep(1000);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
		System.out.println("早饭做好了.........");
	}
}