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

Encapsulation

As previously stated, encapsulation is a key concept in OOP. The principle here is that you protect the data in your class and ensure that the data can only be manipulated (retrieved and/or changed) via your code. In other words, you have control over how external classes interact with your internal state (data). So, how do we do this?

Achieving encapsulation

Basic encapsulation is very easy to achieve. You simply mark your data as private and manipulate the data via public methods. Thus, external classes cannot access the data directly (as it is private); these external classes must go through your public methods to retrieve or change the data.

These public methods make up the class’s "interface"; in other words, how you interact with the class. This “interface” (group of public methods) is very different from and not to be confused with the interface language construct (Chapter 10). Figure 8.16 presents a code example to help...