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

Exploring the super keyword

The super keyword is used in a subclass in two specific scenarios: to call a parent constructor and to access parent members (typically methods). When an object is constructed, the order of constructor calls is very important. Bearing in mind that we now have the possibility of having many classes in an inheritance hierarchy, the order of constructor calls is from the top down. This means that, the parent constructor is always called before the subclass constructor. If you have a hierarchy where Toyota “is-a” Car and Car “is-a” Vehicle, then when you go to create a Toyota object, the order of constructor calls is as follows: Vehicle is first, Car is second, and Toyota is last.

There is a good reason for this. Firstly, remember that the constructor’s role is to initialize the instance members of the class. Now, given that the subclass constructor may use inherited members from its parent when initializing its own members...