package com.ai.ipu.count;

/**
 * 类描述
 *
 * @author lilb3@asiainfo.com
 * @since 2019/8/9
 **/
public class ThreadJoinTestA {

    public static void main(String[] args) throws InterruptedException {
        // TODO Auto-generated method stub
        System.out.println(Thread.currentThread().getName() + " start");
        ThreadTest t1 = new ThreadTest("A");
        ThreadTest t2 = new ThreadTest("B");
        ThreadTest t3 = new ThreadTest("C");
        System.out.println("t1start");
        t1.start();
        System.out.println("t2start");
        t2.start();
        t2.join();
        System.out.println("t3start");
        t3.start();
        System.out.println(Thread.currentThread().getName() + " end");
    }

}

class ThreadTest extends Thread {
    private String name;

    public ThreadTest(String name) {
        this.name = name;
    }

    public void run() {
        for (int i = 1; i <= 5; i++) {
            System.out.println(name + "-" + i);
        }
    }
}

没有添加t2.join()方法之前，t1,t2,t3并行
添加t2.join()方法之后，t1,t2并行，主线程等带t2执行完再往下执行可能还没有运行完>

Java主线程等待所有子线程执行完毕再执行解决办法

1) Thread.join()

t.join(); t是子线程

2) 用线程池。

ExecutorService threadPool = Executors.newScheduledThreadPool(10);

ExecutorService threadPool = Executors.newCachedThreadPool();

3) 写在Main函数里面，会等待子线程执行完。