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

Explaining Java casting

To discuss casting properly, we need to explain both the widening and narrowing of Java’s primitive data types. With this in mind, it is helpful to remember the sizes of the primitive data types in bytes. Table 3.3 represents this information:

Table 3.3 – The sizes of Java’s primitive types

Table 3.3 – The sizes of Java’s primitive types

The preceding table presents the sizes in bytes of Java’s various primitive data types. This will help us as we discuss both widening and narrowing.

Widening

Widening is done automatically; in other words, a cast is not needed. As the promotion is done in the background, widening is also known as implicit promotion. With Table 3.3 in mind, the widening rules are as follows:

byte → short/char → int → long → float → double

Given the sizes from Table 3.3, most of these rules should make sense. For example, a byte can automatically fit into a short because 1 byte fits into...