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Java 9 with JShell

You're reading from   Java 9 with JShell Introducing the full range of Java 9's new features via JShell

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Product type Paperback
Published in Mar 2017
Publisher Packt
ISBN-13 9781787282841
Length 408 pages
Edition 1st Edition
Languages
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Author (1):
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Gaston C. Hillar Gaston C. Hillar
Author Profile Icon Gaston C. Hillar
Gaston C. Hillar
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Table of Contents (16) Chapters Close

Preface 1. JShell – A Read-Evaluate-Print-Loop for Java 9 2. Real-World Objects to UML Diagrams and Java 9 via JShell FREE CHAPTER 3. Classes and Instances 4. Encapsulation of Data 5. Mutable and Immutable Classes 6. Inheritance, Abstraction, Extension, and Specialization 7. Members Inheritance and Polymorphism 8. Contract Programming with Interfaces 9. Advanced Contract Programming with Interfaces 10. Maximization of Code Reuse with Generics 11. Advanced Generics 12. Object-Oriented, Functional Programming, and Lambda Expressions 13. Modularity in Java 9 A. Exercise Answers Index

Working with object initialization and its customization


When you ask Java to create an instance of a specific class, something happens under the hood. Java creates a new instance of the specified type, the JVM (Java Virtual Machine) allocates the necessary memory, and then executes the code specified in the constructor.

When Java executes the code within the constructor, there is already a live instance of the class. Thus, the code in the constructor has access to the fields and methods defined in the class. Obviously, we must be careful in the code we put within the constructor because we might end up generating huge delays when we create instances of the class.

Note

Constructors are extremely useful to execute setup code and properly initialize a new instance.

Let's forget about the hierarchy structure in which we were working for the classes that represent 2D shapes. Imagine that we have to code the Circle class as a standalone class that doesn't inherit from any other class. Before we can...

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