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 functional interfaces from the API

Now, let’s examine some popular functional interfaces defined in the API. Interestingly, the two sorting interfaces from Chapter 13, namely Comparator and Comparable, are both functional interfaces. Comparable defines one abstract method, namely int compareTo(T o), and Comparator defines two abstract methods, namely int compare(T o1, T o2) and boolean equals(Object o). Remember, however, that methods inherited from Object do not count when you’re deciding if an interface is a functional interface or not. As boolean equals(Object o) is inherited from Object, this means that Comparator is a functional interface.

In this section, we will concentrate on the functional interfaces defined in the java.util.function package (https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/function/package-summary.html). This package has a large number of general-purpose functional interfaces that are used by the JDK and are...