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© The Author(s), under exclusive license to APress Media, LLC, part of Springer Nature 2023

J. BarkerBeginning Java Objectshttps://doi.org/10.1007/978-1-4842-9060-6_7

7. Some Final Object Concepts

Jacquie Barker¹

(1)

Fairfax, VA, USA

Polymorphism Simplifies Code Maintenance

Three Distinguishing Features of an Object-Oriented Programming Language

The Benefits of User-Defined Types

The Benefits of Inheritance

The Benefits of Polymorphism

Abstract Classes

Implementing Abstract Methods

Abstract Classes and Instantiation

Declaring Reference Variables of Abstract Types

An Interesting Twist on Polymorphism

Implementing Interfaces

Another Form of the “Is A” Relationship

Interfaces and Casting

Implementing Multiple Interfaces

Interfaces and Casting, ...

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