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

Applying access modifiers

One of the cornerstones of OOP is the principle of encapsulation (data abstraction). Encapsulation can be achieved using access modifiers. Before we discuss encapsulation, we must understand the access modifiers themselves.

Access modifiers determine where a class, field, or method is visible and therefore available for use. The level you are annotating at, determines the available access modifiers:

  • Top level: Classes, enums, records and interfaces – public or package-private (no keyword)
  • Member level: The access modifiers are, in order from most restrictive to least restrictive, private, package-private, protected, and public

Let’s discuss these in turn.

private

A member marked as private is accessible within its own class only. In other words, the block scope of the class defines the boundary. When in a class (scope), you cannot access the private members of another class, even if you have an object reference to...