为什么和老师讲的代码是一样的却运行不了

package com.imooc.concurrent;

public class Actor extends Thread {

public void fun() {

System.out.println(getName() +"is an actor");

int count = 0;

System.out.println(getName() + "show begins"+(++count));

System.out.println(getName() +"show is over");

}

public static void main(String[] args) {

Thread actor = new Actor();

actor.setName("Mr.Thread");

actor.start();

}

}