August 2003
Intermediate to advanced
672 pages
16h 23m
English
book
Programmer's Guide to Java™ Certification, A: A Comprehensive Primer, Second Edition
by Khalid A. Mughal, Rolf W. Rasmussen
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4.8. Other Modifiers for Classes
Modifiers abstract and final can be applied to top-level and nested classes.
abstract Classes
A class can be specified with the keyword abstract to indicate that it cannot be instantiated. A class might choose to do this if the abstraction it represents is so general that it needs to be specialized in order to be of practical use. A class Vehicle might be specified as abstract to represent the general abstraction of a vehicle, as creating instances of the class would not make much sense. Creating instances of non-abstract subclasses, like Car and Bus, would make more sense, as this would make the abstraction more concrete.
A class that has one or more abstract methods (see Section 4.10, p. 147) must be declared ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.