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

Delving into the object life cycle

To understand Java, it is extremely helpful to have an appreciation of what is happening in the background, in memory. This section will help cement what is happening on the stack and the heap when we call methods, declare local/instance variables, and so forth.

Local variables are kept on the stack (for fast access), whereas instance variables and objects live on the heap (a large area of memory). As we know, we use the new keyword to create a Java object. The new keyword allocates space on the heap for the object and returns the reference to the object. What happens if the object is no longer accessible? For example, the reference may have gone out of scope. How do we reclaim that memory? This is where garbage collection comes into play.

Garbage collection

As mentioned previously, garbage collection reclaims memory taken up by objects that are no longer being used; as in the objects have no references pointing to them. This garbage collection...