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Groups > comp.lang.java.programmer > #3189

Re: Partially overriding a method?

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On 4/21/2011 8:31 AM, raphfrk@gmail.com wrote:
> I was wondering if it is possible to override a method but only for
> certain sub-classes of the method that the super-class supports.


Yes and no.  As you discovered, overriding is all or nothing.  You 
either override or you don't.

But you could add your own processing to do what you want with the 
"super" keyword.

<http://download.oracle.com/javase/tutorial/java/IandI/super.html>

>
> For example:
>
> class MainClass {
>      public static void main(String[] args) {
>          System.out.println("Started");
>          MainClass mc = new SubClass();
>          mc.check("Testing");
>          mc.check(7);
>      }
>      void check(Object x) {
>          System.out.println(x.toString());
>      }
> }
>
> class SubClass extends MainClass {
        void check(Object x) {
            if( x instanceof String ) {
               System.out.println("Sub class: " + x);
            } else {
               super.check( x );
            }
>      }
> }
>

The code changes above are untested.

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Thread

Partially overriding a method? "raphfrk@gmail.com" <raphfrk@gmail.com> - 2011-04-21 08:31 -0700
  Re: Partially overriding a method? Lew <noone@lewscanon.com> - 2011-04-21 12:42 -0400
  Re: Partially overriding a method? markspace <-@.> - 2011-04-21 11:37 -0700
    Re: Partially overriding a method? Lew <noone@lewscanon.com> - 2011-04-21 15:58 -0400
  Re: Partially overriding a method? Michal <kleku75@gmail.com> - 2011-04-21 21:00 +0200
  Re: Partially overriding a method? Roedy Green <see_website@mindprod.com.invalid> - 2011-04-21 12:59 -0700
  Re: Partially overriding a method? Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-04-21 21:10 -0400
    Re: Partially overriding a method? "raphfrk@gmail.com" <raphfrk@gmail.com> - 2011-04-24 09:39 -0700

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