一个Java方法覆盖的小问题

 class SuperClass{

 public SuperClass() {
     System.out.println("superclass ");
     show();
 }
 public void show() {
     System.out.println("super class show !");
 }
 }
 class Subclass extends SuperClass{

     public Subclass() {
         super();
         super.show();
         System.out.println("subclass ");
         show();
     }
     public void show(){

         System.out.println("sub class  show !");
     }

 }
 public class Test {
 public static void main(String[] args) {
     Subclass sub = new Subclass();
 }
 }

为什么这个结果？？？？？