overriding

[kri shan]

Can I declare a superclass method whose modifier is 'public' as private in subclass while overriding?

[Marilyn de Queiroz]

Did you try it? What happened?

[satish sathineni]

Hi kri shan

While Overriding the superclass method in the sub class

1. The access modifier of the subclass overriding method should be
below the acess modifier level of the super class method acess modifier.

ex :: public void MethodA() // super class method

ex :: protected void MethodA() // sub class method

The accessmodifier can be descending when compared to super class acess modifier.
Private,Protected,default,Public

[Vijayendra V Rao]

Originally posted by kri shan:
Can I declare a superclass method whose modifier is 'public' as private in subclass while overriding?

No. In simple words, the subclass method should be atleast as visible as it's corresponding superclass method. This is the minimum requirement. If the superclass method is public, then you have no other choice but to have your subclass method too as public.

[Sadanand Murthy]

Originally posted by satish_kumar:
Hi kri shan

While Overriding the superclass method in the sub class

1. The access modifier of the subclass overriding method should be
below the acess modifier level of the super class method acess modifier.

ex :: public void MethodA() // super class method

ex :: protected void MethodA() // sub class method

The accessmodifier can be descending when compared to super class acess modifier.
Private,Protected,default,Public

When you say "below" are you refering to some hierarchy or narrowness/width of the scope? If it is the latter, then it is not correct. You cannot narrow the scope of a subclass from that of its superclass. If it is the former, then is the hierarchy what you have listed in the last line of your post? In that case you are mostly right. A subclass of a public super class can have the default scope.

[beth ana]

The rules of method overriding:

SuperClass SubClass
public must be overriden public.
Protected can be public, protected
default/no modifier can be public, protected, default/no modifier
private can be public, protected, default/no modifier
static combination must be static combination
abstract must be overriden
final cannot be overriden
native don't know - try out

There are rules of overriding in case of excepion handling for checked & unchecked exceptions.
Let me If I am reasonable.

[JulianInactive KennedyInactive]

Amended table for method overriding:

Superclass method modifier   Subclass modifiers
==========================   ==============================================
public                       public 
protected                    public, protected
package (i.e. default)       public, protected, package
private                      This is not overriding as private methods are not visible to subclasses
static                       This is not overriding, it's shadowing (as with member variables).
                             Static method calls are not resolved dynamically.
abstract                     Must be overridden or abstract
final                        Cannot be overridden
native                       Not sure, but don't see why this would be a special case.  Anyone?

I think I'm right with these, but there's almost always something you miss when you do things from memory... :roll:

Jules

[ August 04, 2004: Message edited by: Julian Kennedy ]
[ August 04, 2004: Message edited by: Julian Kennedy ]

[Irina Goble]

In simple words, a subclass must provide more access if it changes the access of a method.
There is no reason to give less access as the method can be accessed by a reference to the superclass with more access.