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Interface

Ingoba Ningthoujam
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Joined: Dec 04, 2006
Posts: 90
How to implement selected methods of an interface?
Jesper de Jong
Java Cowboy
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Joined: Aug 16, 2005
Posts: 14349
    
  22

Ingoba, can you explain your question in more detail - what do you mean exactly?

Have a look at The Java Tutorial:
Lesson: Interfaces and Inheritance


Java Beginners FAQ - JavaRanch SCJP FAQ - The Java Tutorial - Java SE 8 API documentation
Ingoba Ningthoujam
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Joined: Dec 04, 2006
Posts: 90
Thanks for your concern. I will elaborate my question.

I defined one interface having three methods. I want to implement only two methods of this interface in a class.How can it be done? Please reply.
Ådne Brunborg
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Joined: Aug 05, 2005
Posts: 208
Either

1) Define a different interface to implement. Remember, interfaces can extend other interfaces, and in this case you could define two methods in one interface and the third in a subinterface of that.

or

2) Implement the method to throw java.lang.UnsupportedOperationException:



If your class "implements" an interface, you must implement all methods that interface requires.
[ December 06, 2006: Message edited by: �dne Brunborg ]

Entia non sunt multiplicanda praeter necessitatem
Jesper de Jong
Java Cowboy
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Joined: Aug 16, 2005
Posts: 14349
    
  22

You can write a class that implements the interface, but if the class does not implement all methods of the interface, the class has to be an abstract class.

If you don't want the class to be abstract, then you must implement all the methods of the interface. If you don't know what to do with the third method, you can provide an implementation that for example throws an UnsupportedOperationException like �dne shows, but that may not be what you want.
Sanjit Kumar
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Joined: Dec 04, 2006
Posts: 35
Adne has given the best explanation of this question.
 
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subject: Interface