[Java] Thread 创建线程的第二种方法

public class Thread4{
    public static void main(String[] args){
        //利用多态
        Thread t = new RunnableTest3();
        t.start();
    }
}
//用继承Thread父类的方法来定义
class RunnableTest3 extends Thread{
    @Override
        public void run(){
            for(int i= 0;i<20;i++){
                String str = Thread.currentThread().getName();
                System.out.println(str+":"+i);
            }
        }
}