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

Arrays – what, when, and why?

So far, we’ve only seen single values, such as int, double, and String. Imagine we want to calculate an average result. That would look something like this:

double result1 = 7.0;double result2 = 8.6;
double result3 = 9.0;
double total = result1 + result2 + result3;
double average = total / 3;
System.out.println(average);

This code isn’t very scalable. If we were to add a fourth result, we would need to do three things in order to make this work:

  • Declare and initialize a fourth variable
  • Add this fourth variable to the total
  • Divide by 4 instead of 3

This is a hassle, and it is error-prone. If we knew arrays, we could alter this by only changing one element of our code. Let’s see what arrays are. Then, we will rewrite this example once we get to iterate over arrays.

Java can’t do basic math?!

If you were to run the previous code snippet, you’d see something interesting. If I asked...