Meaningless Drivel is fun!
The moose likes Java in General and the fly likes related to Abstract class Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login
JavaRanch » Java Forums » Java » Java in General
Bookmark "related to Abstract class" Watch "related to Abstract class" New topic

related to Abstract class

padmaratna kamble

Joined: Apr 26, 2006
Posts: 26
I want to know Abstract class has constructor but we can not initiate. why?
and why interface not have constructor?
please help me.
Thanks in advance.
Ernest Friedman-Hill
author and iconoclast

Joined: Jul 08, 2003
Posts: 24199

An abstract class can have instance variables; the purpose of a constructor is to initialize member variables. Although you can't instantiate an abstract class directly, every subclass of that abstract class must call one of the abstract class's constructors from its own constructors; this give the abstract class a chance to initialize its members.

An interface can't have a constructor, as you say. Since an interface cannot have any instance variables, a constructor would serve no purpose. In any case, an interface can't contain any member methods at all, so of course it can't have constructors either.

[Jess in Action][AskingGoodQuestions]
I agree. Here's the link:
subject: related to Abstract class
jQuery in Action, 3rd edition