interface

**makrandubale** · 01-02-2011, 01:10 PM

hi, if a class implements two interfaces, Interface1 and Interface2, and both the interfaces have a method with same signature then no matter what reference (the class or any of the interfaces) i use to invoke the method, the same method will be executed. can some one give an ex. which can explain the benifits of implementing two interfaces with the same method signatures.

**JosAH** · 01-02-2011, 01:22 PM

Originally Posted by makrandubale

hi, if a class implements two interfaces, Interface1 and Interface2, and both the interfaces have a method with same signature then no matter what reference (the class or any of the interfaces) i use to invoke the method, the same method will be executed. can some one give an ex. which can explain the benifits of implementing two interfaces with the same method signatures.

There is no benefit, the compiler just can't forbid you to do so. Try to circumvent such a situation by renaming one of the methods.

kind regards,

Jos

**makrandubale** · 01-02-2011, 01:30 PM

thanks for the reply Jos. but don't you think, that java allows such kinda implementation leaving the developer in confusion whereas C++ is strict about not allowing such kinda implementation.

**JavaHater** · 01-02-2011, 01:30 PM

Originally Posted by JosAH

Tjust can't forbid you to do so.

"can't forbid" means "to allow". is that really what you mean?

**makrandubale** · 01-02-2011, 01:34 PM

the complier allows it.. so we can conclude as YES

**JosAH** · 01-02-2011, 02:10 PM

Originally Posted by makrandubale

the complier allows it.. so we can conclude as YES

Indeed; the language would need to be changed to 'fix' this, i.e. the method overloading mechanism needs to be changed, additional keywords or whatever need to be defined all for this. It is much easier and cheaper to allow a single method implementation to 'fit' two or more interfaces. Java is not C++.

kind regards,

Jos

**makrandubale** · 01-02-2011, 02:19 PM

ya, java tried to solve the C++ diamond problem (for the compiler), and left the decision on the developers.... good busniess logic :)

**JosAH** · 01-02-2011, 02:28 PM

Originally Posted by makrandubale

ya, java tried to solve the C++ diamond problem (for the compiler), and left the decision on the developers.... good busniess logic :)

That's all because multiple inheritance of implementation and Java doesn't allow that. There are already too many ugly dark corners in Java (you just found one).

kind regards,

Jos

**makrandubale** · 01-02-2011, 02:53 PM

hye.. can you share some more similar things?

**JosAH** · 01-02-2011, 03:13 PM

Originally Posted by makrandubale

hye.. can you share some more similar things?

Similar thing ... my pet peeve complaint is that one isn't allowed to refer to member variables of an object before the object is constructed (which is understandable) while it is allowed to use methods called by a superclass constructor that can be overridden by a subclass. I understand why it happens (simplicity of the vtab at construction time) but I just don't like it ;-)

kind regards,

Jos