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interface & delegate
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Interface vs. abstract class
Choosing interfaces and abstract classes is not an either/or
proposition. If you need to change your design, make it an interface.
However, you may have abstract classes that provide some default
behavior. Abstract classes are excellent candidates inside of
application frameworks.
Abstract classes let you define some behaviors; they force your
subclasses to provide others. For example, if you have an application
framework, an abstract class may provide default services such as
event and message handling. Those services allow your application to
plug in to your application framework. However, there is some
application-specific functionality that only your application can
perform. Such functionality might include startup and shutdown tasks,
which are often application-dependent. So instead of trying to define
that behavior itself, the abstract base class can declare abstract
shutdown and startup methods. The base class knows that it needs those
methods, but an abstract class lets your class admit that it doesn't
know how to perform those actions; it only knows that it must initiate
the actions. When it is time to start up, the abstract class can call
the startup method. When the base class calls this method, Java calls
the method defined by the child class.
Many developers forget that a class that defines an abstract method
can call that method as well. Abstract classes are an excellent way to
create planned inheritance hierarchies. They're also a good choice for
nonleaf classes in class hierarchies.
from http://www.javaworld.com/javaworld/javaqa/2001-04/03-qa-0420-abstract.html
On Fri, 14 May 2004 00:39:20 -0700, dotNET User Group Hyd
<[EMAIL PROTECTED]> wrote:
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> interface & delegate
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> From: imparesh007
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> Hi Lakshmi,
>
> thanx for the explanation.
>
> Bye
> Pares
>
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