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ADT? What is it??

Aditya Herlambang

Joined: Feb 01, 2007
Posts: 11
Hey guys I just learned about this what is called ADT in java, but still I don't quite understand what it is. I tried reading the books several times but still I can't get the concept of what it is.
There is also a keyword 'extend', what is that actually?? There is also the terminology of collection, Set<E>, bag, and List ADT. What is all that about?? Can someone explain it to me very briefly?? Many thanks to those who are willing to help me
Jeanne Boyarsky
author & internet detective

Joined: May 26, 2003
Posts: 32819

Welcome to JavaRanch!

ADT stands for abstract data type. It is a data type that can be implemented in different ways. For example, Set is an interface that defines the methods you can expect in a set. AbstractSet implements some of the methods. It is still abstract though as the implementation may vary. There are several concrete implementations of Set like HashSet (uses keys) and TreeSet (uses sorting.)

The "extends" keyword defines a superclass. For example, HashSet extends AbstractSet in that it adds implementation to the abstract type.

Wikipedia explains this in more detail. If you have any more specific questions, feel free to reply to this thread.

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Aditya Herlambang

Joined: Feb 01, 2007
Posts: 11
and what is the relationship between ADT and class?
I agree. Here's the link:
subject: ADT? What is it??
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