Book Image

Java 9 with JShell

By : Gaston C. Hillar
Book Image

Java 9 with JShell

By: Gaston C. Hillar

Overview of this book

The release of Java 9 has brought many subtle and not-so-subtle changes to the way in which Java programmers approach their code. The most important ones are definitely the availability of a REPL, known as JShell, which will make experiments and prototyping much more straightforward than the old IDE-based project-led approach. Another, more subtle change can be seen in the module system, which will lead to more modularized, maintainable code. The techniques to take full advantage of object-oriented code, functional programming and the new modularity features in Java 9 form the main subjects of this book. Each chapter will add to the full picture of Java 9 programming starting out with classes and instances and ending with generics and modularity in Java.
Table of Contents (23 chapters)
Java 9 with JShell
Credits
About the Author
Acknowledgement
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
Index

Creating methods that work with instances of different subclasses


After we declare all the new classes, we will create the following two methods that receive a VirtualAnimal instance as an argument, that is, a VirtualAnimal instance or an instance of any subclass of VirtualAnimal. Each method calls a different instance method defined in the VirtualAnimal class: printAverageNumberOfBabies and printAsciiArg. The code file for the sample is included in the java_9_oop_chapter_07_01 folder, in the example07_02.java file.

void printBabies(VirtualAnimal animal) {
    animal.printAverageNumberOfBabies();
}

void printAsciiArt(VirtualAnimal animal) {
    animal.printAsciiArt();
}

Then the following lines create instances of the next classes: Cockatiel, VirtualDomesticRabbit, and MaineCoon. The code file for the sample is included in the java_9_oop_chapter_07_01 folder, in the example07_02.java file.

Cockatiel tweety = 
    new Cockatiel(3, "White", "Tweety");
VirtualDomesticRabbit bunny = 
    new VirtualDomesticRabbit...