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)

NullPointerException – Have No Fear

We presented the concept of null within Java in a previous chapter. As you may recall, null is the value that is implicitly assigned to an object upon creation, that is, unless you assign a different value to it. Related to null is the NullPointerException value. This is a very common event that can and will happen to you for a variety of reasons. In this section, we will highlight some of the most common scenarios of this in an effort to introduce you to a different way of thinking when dealing with any type of exception in your code.

In Example01, we examined the process of trying to perform operations on an object that was pointing to null. Let's look at some other possible cases:

public class Example04 {
    public static void main(String[] args) {
        String vehicleType = null;
        String vehicle = "car";
&...