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

Contrasting instance with class members

An object can be more correctly termed an object instance. This is where instance members (methods/data) get their names: every object gets a copy of an instance member. Class members, however, are different in that there is only one copy per class, regardless of the number of object instances created. We’ll discuss both of these topics now.

Instance members (methods/data)

This is more easily explained by presenting a code example first. Figure 8.3 presents a class with instance members:

Figure 8.3 – A class with instance members

Figure 8.3 – A class with instance members

When you create an object using new, you are creating an object instance. Each instance gets a copy of the instance members (variables and methods). Regarding instance variables, we need to define where instance variables are declared and their resultant scope. An instance variable is defined within the class but outside every method coded in the class. Thus, the scope...