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

Short syntax for array initialization

We can use Java’s shortcut syntax for declaring and initializing arrays with specific values. Instead of declaring and initializing the array separately, we can use curly braces ({}) to specify the elements directly. Take a look at the following example:

int[] ages = {31, 7, 5, 1, 0};

This code creates an array of integers and initializes it with the specified values. The size of the array is determined by the number of elements inside the curly braces.

Actually, our previous arrays had values already as well, because when you create an array using the new keyword, Java automatically initializes the elements with default values based on their data type. The default values are as follows:

  • Numeric types (byte, short, int, long, float, double): 0 or 0.0
  • char: ‘\u0000’ (the Unicode null character)
  • boolean: false
  • Reference types (objects and arrays): null

For example, say you create an array of...