Installing and Verifying the JDK

Getting Started: Choosing and Downloading the JDK

Before we begin the installation, it's helpful to know that there are a few different providers of the JDK. The two most common are:

• Oracle JDK: The official JDK from Oracle, the company that stewards Java.
• OpenJDK: A free and open-source implementation of the Java Platform.

For learning and general development, OpenJDK is an excellent choice. Major companies like Amazon, Microsoft, and Red Hat provide their own builds of OpenJDK.

You will also see version numbers, some marked with "LTS," which stands for Long-Term Support. These versions (like JDK 17, 21, etc.) are guaranteed to receive updates for several years, making them stable and reliable choices. For this course, we recommend using JDK 21 (LTS).

The following resource from GeeksforGeeks provides a comprehensive guide to downloading and installing the JDK. We will walk through the key parts of this process together.

The Installation Process

Installing the JDK involves three main steps:

1. Downloading the correct installer for your operating system.
2. Running the installer to place the Java files on your computer.
3. Configuring environment variables to tell your operating system where to find the Java tools.

This third step is the most technical but also the most important for ensuring you can run Java commands from your terminal or command prompt. It involves telling your system's PATH where the Java compiler (javac) and launcher (java) are located.

The installation procedure varies depending on your operating system. Please follow the instructions for your specific system: Windows, macOS, or Linux.

Instructions for Windows

For Windows users, the process involves running a graphical installer and then manually setting the environment variables through the System Properties window. The following video provides a clear, step-by-step visual guide.

For a detailed textual reference with screenshots that you can follow at your own pace, the GeeksforGeeks article is an excellent companion.

Instructions for macOS

On macOS, the installation is done via a .dmg file. Afterward, you'll need to configure your shell's startup file (usually .zshrc) to set the necessary environment variables.

This video from ProgrammingKnowledge is a great walkthrough for the entire process on a modern Mac.

You can also use the GeeksforGeeks article for a textual version of these steps.

Instructions for Linux

For Linux users, installation is typically handled through your distribution's package manager from the terminal, which often simplifies the process. The main task is ensuring the JAVA_HOME environment variable is set correctly.

Since there is no video resource for Linux, please rely on the detailed written guides below. Both provide the necessary commands for Debian/Ubuntu, Fedora/RHEL, and other distributions.

As an alternative, this DEV Community post offers a more concise guide that also covers multiple Linux distributions.

Verifying Your Installation

Once you have completed the installation and configured the environment variables, the final step is to verify that everything works. You will do this using your system's command-line interface: Command Prompt on Windows, or Terminal on macOS and Linux.

Open a new terminal or command prompt window (this is important, as it ensures the new environment variables are loaded). Type the following command and press Enter:

java -version

You should see output that tells you the installed Java version. Next, type this command and press Enter:

javac -version

The javac command is the Java compiler. Seeing a version number for this command confirms that the full Development Kit (not just the runtime) is correctly installed and configured in your system's PATH.

Your output should look something like this:

If you see version numbers for both commands, congratulations! Your Java Development Kit is ready to go. If you get an error like "command not found," the most likely cause is an issue with the environment variables. Please revisit the configuration steps for your operating system carefully.

Conclusion

In this lesson, you've taken the first and most crucial practical step in your Java journey. You have successfully installed the Java Development Kit and verified that your computer is now set up for Java development.

Here are the key takeaways:

• The JDK (Java Development Kit) is essential for developing Java applications. We recommend using an LTS version like JDK 21.
• The installation process consists of downloading, installing, and, most importantly, configuring environment variables (JAVA_HOME and PATH).
• The process differs slightly for Windows, macOS, and Linux, but the goal is the same: making the java and javac commands accessible from the command line.
• Verification is done by running java -version and javac -version in a new terminal window.

Now that your machine has the core Java toolset, you're almost ready to write code. However, you could write code in a simple text editor, compiling and running it from the command line, this can be cumbersome. To make our development process much more efficient and enjoyable, we will next install an Integrated Development Environment (IDE). In the next lesson, we'll set up a powerful IDE that will serve as your primary tool for writing, debugging, and managing your Java projects.