2-8自由编程

package test_4;

class Cat implements Runnable{

@Override

public void run() {

// TODO Auto-generated method stub

for (int i = 0; i < 3; i++) {

System.out.println(Thread.currentThread().getName()+"A Cat");

}

}

}

class Dog implements Runnable{

@Override

public void run() {

// TODO Auto-generated method stub

for (int i = 0; i < 3; i++) {

System.out.println(Thread.currentThread().getName()+"A Dog");

}

}

}

public class Lab_9_1 {

public static void main(String[] args){

    Cat cat=new Cat();

    Thread aThread=new Thread(cat);

    Dog dog=new Dog();

    Thread bThread=new Thread(dog);

    aThread.start();

    bThread.start();

    for (int i = 0; i < 3; i++) {

System.out.println("main thread");

}

}

}

1、是这样写吗  

2、主线程不一定在其他线程之前运行吗