多线程顺序打印firstsecondthird

三个不同的线程 A、B、C 将会共用一个 Foo 实例。

    一个将会调用 first() 方法
    一个将会调用 second() 方法
    还有一个将会调用 third() 方法

请设计修改程序，以确保 second() 方法在 first() 方法之后被执行，third() 方法在 second() 方法之后被执行。

题目来源：https://leetcode-cn.com/problems/print-in-order

/**
*@Title Foo.java
*@description TODO
*@time 2021年3月16日 下午12:29:10
*@author lyj
*@version 1.0
**/
package org.threadTest;

import java.util.concurrent.CountDownLatch;

/**
 * @author lyj
 *
 */
public class Foo {

	/**
	 * @Title: main
	 * @Description:
	 * @param args
	 * @return void
	 * @author lyj
	 * @date 2021年3月16日下午12:29:10
	*/

	    private CountDownLatch countDownLatchA;
	    private CountDownLatch countDownLatchB;

	    public Foo() {
	        countDownLatchA = new CountDownLatch(1);
	        countDownLatchB = new CountDownLatch(1);
	    }

	    public void first(Runnable printFirst) throws InterruptedException {
	        // printFirst.run() outputs "first". Do not change or remove this line.
	        printFirst.run();
	        countDownLatchA.countDown();
	    }

	    public void second(Runnable printSecond) throws InterruptedException {
	        // printSecond.run() outputs "second". Do not change or remove this line.
	        countDownLatchA.await();
	        printSecond.run();
	        countDownLatchB.countDown();
	    }

	    public void third(Runnable printThird) throws InterruptedException {
	        // printThird.run() outputs "third". Do not change or remove this line.
	        countDownLatchB.await();
	        printThird.run();
	    }
	}

/**
*@Title OrderPrintThread.java
*@description TODO
*@time 2021年3月16日 下午12:23:28
*@author liuyijiao
*@version 1.0
**/
package org.threadTest;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * @author lyj
 *
 */
public class OrderPrintThread {

	/**
	 * @Title: main
	 * @Description:
	 * @param args
	 * @return void
	 * @author lyj
	 * @date 2021年3月16日下午12:23:29
	*/
	public Thread   printFirst() {
		Thread thread=new Thread(
		 new Runnable() {
			public void run() {
				System.out.print("first");
			}
		});
		return thread;
	}
    public Thread   printSecond() {
    	Thread thread=new Thread(
    			 new Runnable() {
			public void run() {
				System.out.print("sencond");
			}
    			 });
		return thread;
	}
    public Thread   printThird() {
    	Thread thread=new Thread(
    		 new Runnable() {
			public void run() {
				System.out.print("third");
			}
		 });
			return thread;
	}
	public void toStartThread(int threadName,Foo foo) throws InterruptedException {
		if(threadName==1) {
			 foo.first(printFirst());
		}else if(threadName==2) {
			foo.second(printSecond());
		}else if(threadName==3) {
			foo.third(printThird());
		}
	}
	public static void main(String[] args)  {
		//args=1 2 3  //3 2 1 // 2 1 3
		 ExecutorService es=Executors.newFixedThreadPool(3);
		  Foo  foo=new Foo();
		  OrderPrintThread opt=new OrderPrintThread();
		 for(int i=0;i<3;i++) {
			   int local=i;
				 es.execute(new Runnable() {
					@Override
					public void run() {
						  try {
							  int arg=Integer.valueOf(args[local]);
							  opt.toStartThread(arg, foo);
						} catch (Exception e) {
							e.printStackTrace();
						}
					}
				});
		 }
		 es.shutdown();

	}
}