并发---加入一个线程 join

join

• 一个线程可以在其他线程之上调用join（）方法，其效果是等待一段时间直到第二个线程结束才继续执行。如果某个线程在另一个线程t上调用t.join（），此线程将被挂起，直到目标线程t结束才恢复（即t.isAlive()返回为假）
• 也可以在调用join（）时带上一个超时参数（单位可以是毫秒，或者毫秒和纳秒），这样如果目标线程在这段时间到期时还没有结束的话，join（）方法总能返回。
• 对join（）方法的调用可以被中断，做法是在调用线程上调用interrupt（）方法，这时需要用到try-catch子句。

/**
 * Created by Panda on 2018/6/4.
 */
class Sleeper extends Thread{
    private int duration;
    public Sleeper(String name,int sleepTime){
        super(name);
        duration=sleepTime;
        start();
    }
    public void run(){
        try{
            sleep(duration);
        }catch (InterruptedException e){
            System.out.println(getName()+" was interrupted. "+"isInterrupted()； "+isInterrupted());
            return;
        }
        System.out.println(getName()+" has awakened");
    }
}
class Joiner extends Thread{
    private Sleeper sleeper ;
    public Joiner(String name,Sleeper sleeper){
        super(name);
        this.sleeper=sleeper;
        start();
    }
    public void run(){
        try{
            sleeper.join();
        }catch (InterruptedException e){
            System.out.println("Interrupted");
        }
        System.out.println(getName()+" join completed");
    }
}
public class Joining {
    public static void main(String[] args) {
        Sleeper sleeper =new Sleeper("sleeper1",1500);
        Sleeper sleeper1=new Sleeper("sleeper2",1500);

        Joiner joiner1=new Joiner("joiner1",sleeper);
        Joiner joiner2=new Joiner("joiner2",sleeper1);

        sleeper1.interrupt();
    }
    /**
     * sleeper2 was interrupted. isInterrupted()； false
     joiner2 join completed
     sleeper1 has awakened
     joiner1 join completed
     */
}