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

Understanding and declaring variables

If you want to store a value for later use, you need a variable. Therefore, every programming language provides this feature via variables. In this section, we will learn what a variable is and how to declare one. The area in your code where you can use a particular variable is known as the variable’s scope. This is a very important concept and will be covered in detail in Chapter 4.

What is a variable?

Variables are locations in memory that have a name (called an identifier) and a type. They resemble named pigeonholes or post office boxes (see Figure 2.1). The variable’s name is required so that we can refer to the variable and distinguish it from other variables.

A variable’s type specifies the sort of values it can store/hold. For example, is the variable to be used for storing whole numbers such as 4 or decimal numbers such as 2.98? The answer to that question determines the variable’s type.

Declaring...