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

Declaring and initializing arrays

There are different ways to declare and initialize arrays in Java. What you’ll need will depend a lot on the specific situation. So, let’s just start with the basics of declaring arrays.

Declaring arrays

To declare an array in Java, you need to specify the data type of the elements, followed by square brackets ([]) and the array’s name. Take the following example:

int[] ages;

Here, int[] is the data type of the array, and ages is the name of the array. Right now, we can’t add any values to the array, because it hasn’t been initialized yet. This is different from initializing variables, which we have seen so far. Let’s see how to initialize arrays next.

Initializing arrays

After declaring an array, it needs to be initialized. We do this by specifying its size and allocating memory for the elements. We can use the new keyword to do this, followed by the data type, and then specify the size of...