how to call a overridden method from subclass object in java

Question

Is there a way to call test() in class a from class b object created in class c ?

class a {
 void test(){
   System.out.println("in a");
  }
}

 class b extends a {
   void test(){
     System.out.println("in b");
   }
}

public class c{
 public static void main(String[] args) {
   b refb = new b();
   refb.test();
  }
}

the super keyword, but then that would be from within b. – Stultuske May 28 '14 at 06:47 — Stultuske, May 28 '14 at 06:47

score 2 · Answer 1 · answered May 28 '14 at 06:48

2

You can do that only within the test() method of class b like following.

class b extends a {
   void test(){
     super.test();
     System.out.println("in b");
   }
}

answered May 28 '14 at 06:48

Abimaran Kugathasan

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Thanks, but i dont want to change class b code, is there a way to call from b's object refb in class c – Jayadeep May 28 '14 at 06:51
@Jayadeep; That's a violation of encapsulation. You can't do that. May be you are doing something wrong. – Abimaran Kugathasan May 28 '14 at 06:59
@AbimaranKugathasan that won't be the case in languages like C++ or C# where you can leave the method as non-`virtual`. See my answer. – Luiggi Mendoza May 28 '14 at 07:03
@LuiggiMendoza : I'm not familiar with C# or C++. But, in java, we can't do it in this way. – Abimaran Kugathasan May 28 '14 at 07:06

score 0 · Answer 2 · answered May 28 '14 at 06:51

In Java, all non static private methods are virtual by default. So, there's no way to invoke a#test from b instance unless you modify b#test. The only way to do it (by your current design) is using an instance of a:

public class c{
    public static void main(String[] args) {
        b refb = new b();
        // code to call test() in class a
        //this is the only way you have in Java
        a refA = new a();
        a.test();
    }
}

how to call a overridden method from subclass object in java

2 Answers2