Java Cookbook, 1st Edition

Chapter 1. Getting Started: Compiling and Running Java

1.0 Introduction

This chapter covers some entry-level tasks that you need to know how to do before you can go on. It is said you must crawl before you can walk, and walk before you can ride a bicycle. Before you can try out anything in this book, you need to be able to compile and run your Java code. I start by demonstrating several methods: using the Java Development Kit (JDK), an Integrated Development Environment (IDE), and build tools like Maven and Gradle. Another issue people run into is setting CLASSPATH correctly, so that’s dealt with next. Deprecation warnings follow after that, because you’re likely to encounter them in maintaining old Java code. The chapter ends with some general information about unit testing and assertions.

If you don’t have Java installed, you’ll need either to download the JDK on its own, particularly to the command-line Java, or download an IDE that includes its own JDK. Be aware that in historical releases there were different downloads, the Java Runtime Environment (JRE) and the JDK. Up until Java 8, the JRE was a smaller download for end users (i.e., just the parts needed to run a Java app, but not to compile one). Since there is less desktop Java than there once was, and since hard disks have gotten much bigger, the JRE was eliminated in favor of creating jlink as part of the JDK, to create custom downloads of the JDK (see Recipe 2.17). The JDK download (sometimes referred to as the Java ...