Book Image

Learn Java with Projects

By : Dr. Seán Kennedy, Maaike van Putten
5 (3)
Book Image

Learn Java with Projects

5 (3)
By: Dr. Seán Kennedy, Maaike van Putten

Overview of this book

Learn Java with Projects stands out in the world of Java guides; while some books skim the surface and others get lost in too much detail, this one finds a nice middle ground. You’ll begin by exploring the fundamentals of Java, from its primitive data types through to loops and arrays. Next, you’ll move on to object-oriented programming (OOP), where you’ll get to grips with key topics such as classes, objects, encapsulation, inheritance, polymorphism, interfaces, and more. The chapters are designed in a way that focuses on topics that really matter in real-life work situations. No extra fluff here, so that you get more time to spend on the basics and form a solid foundation. As you make progress, you’ll learn advanced topics including generics, collections, lambda expressions, streams and concurrency. This book doesn't just talk about theory—it shows you how things work with little projects, which eventually add up to one big project that brings it all together. By the end of this Java book, you’ll have sound practical knowledge of Java and a helpful guide to walk you through the important parts of Java.
Table of Contents (22 chapters)
1
Part 1: Java Fundamentals
9
Part 2: Object-Oriented Programming
15
Part 3: Advanced Topics

Exploring polymorphism

Polymorphism has its origins in the Greek terms poly (many) morphe (forms). Any object that passes more than one “is-a” test can be considered polymorphic. Therefore, only objects of the Object type are not polymorphic as any type passes the “is-a” test for both Object and itself.

In this section, we will discuss why separating the reference type from the object type is so important. In addition, we will examine method overriding and its critical role in enabling polymorphism.

Separating the reference type from the object type

Now that we have inheritance hierarchies, we will regularly differentiate the reference type from the object type. The reference type can be a class, record, enum or interface. In other words, we have flexibility with regard to the reference type. The object type is more restrictive: the object type is based on non-abstract classes, records, and enums only. In other words, we cannot create objects based...