orden de ejecución hilo

package com.pra;

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

/**
 * @author evi
 * @version 1.0.0
 * @date 2019\8\15   22:00
 */
public class MewThread {
    static Thread thread1=new Thread(new Runnable() {
        @Override
        public void run() {
            System.out.println("thread1 执行");
        }
    });

    static Thread thread2=new Thread(new Runnable() {
        @Override
        public void run() {
            System.out.println("thread2 执行");
        }
    });

    static Thread thread3=new Thread(new Runnable() {
        @Override
        public void run() {
            System.out.println("thread3 执行");
        }
    });

    static ExecutorService executorService=Executors.newSingleThreadExecutor();

    public static void main(String[] args) throws InterruptedException {

//        //join:让主线程等待子线程结束以后才能继续运行
//        System.out.println("Hello World");
//        thread1.start();
//        thread1.join();
//        thread2.start();
//        thread1.join();
//        thread3.start();


        executorService.submit(thread1);
        executorService.submit(thread2);
        executorService.submit(thread3);
        executorService.shutdown();
    }
}