Book Image

The Java Workshop

By : David Cuartielles, Andreas Göransson, Eric Foster-Johnson
4 (2)
Book Image

The Java Workshop

4 (2)
By: David Cuartielles, Andreas Göransson, Eric Foster-Johnson

Overview of this book

Java is a versatile, popular programming language used across a wide range of industries. Learning how to write effective Java code can take your career to the next level, and The Java Workshop will help you do just that. This book is designed to take the pain out of Java coding and teach you everything you need to know to be productive in building real-world software. The Workshop starts by showing you how to use classes, methods, and the built-in Collections API to manipulate data structures effortlessly. You’ll dive right into learning about object-oriented programming by creating classes and interfaces and making use of inheritance and polymorphism. After learning how to handle exceptions, you’ll study the modules, packages, and libraries that help you organize your code. As you progress, you’ll discover how to connect to external databases and web servers, work with regular expressions, and write unit tests to validate your code. You’ll also be introduced to functional programming and see how to implement it using lambda functions. By the end of this Workshop, you’ll be well-versed with key Java concepts and have the knowledge and confidence to tackle your own ambitious projects with Java.
Table of Contents (20 chapters)

Checking the Precedence of a Class with instanceof

You can check whether an object is an instance of a specific class. This can be convenient for things such as error checking, handling data in different ways depending on its precedence, and more. The following example shows the checkNumber method, which can discriminate between different types of variables and will print different messages based on that:

public class Example04 {
    public static void checkNumber(Number val) {
        if( val instanceof Integer )
            System.out.println("it is an Integer");
        if( val instanceof Double )
            System.out.println("it is a Double");
    public static void main(String[] args) {