关于static

class That{
    protected String nm(){
        return "that";
    }
}

public class More extends That{
    protected String nm(){
       return "more";
    }
    protected void printNM(){
        That sref=(That)this;
        System.out.println("this.nm()="+this.nm());
        System.out.println("sref.nm()="+sref.nm());
        System.out.println("super.nm()="+super.nm());

    }
   
    public static void main(String[] args){
         More duixiang= new More();
         duixiang.printNM();
        //直接调用方法必须是必须是静态的

      //printNM();就是错的

    }

}