java中的多线程

public class Jpu{
    public static void main(String[] args){
     China1 obj1=new China1();
     China2 obj2=new China2();
     obj1.start();
     obj2.start();
    
     }  
}

class China1 extends Thread{
    public void run(){
        System.out.println("thread1!"); 
     
    } 
}

class China2 extends Thread{
     public void run(){
       System.out.println("thread2!");
        
     } 
   
 
}