How to Install OpenJDK in macOS

Java is a popular programming language used to build web, mobile, and desktop applications. To create and run Java programs, you need the Java Development Kit (JDK). OpenJDK is the free and open-source version of the JDK, widely used by developers on macOS and other systems.

You can install OpenJDK on macOS in two simple ways:

• Using Homebrew: Easy and quick installation using the macOS package manager.
• Manual Installation: Download and install the JDK directly from the official website.

Methods to Install OpenJDK in macOS

Method 1: Using Homebrew

Homebrew is a package manager for macOS that makes software installation simple and quick.

Step 1: Check If Java Is Already Installed

• Before installing OpenJDK, check if Java is already installed on your macOS:
• Open the Terminal (press ⌘Command + Space, type Terminal, and hit Enter).
• Type the following command:

java -version

• If Java is installed, you will see the version number. If not, you will see a message saying Java is not installed.

Step 2: Install Homebrew (If Not Installed)

• Homebrew is a package manager for macOS that makes it easy to install software like OpenJDK. To check if Homebrew is installed, run:

brew --version

• If Homebrew is not installed, install it using this command:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

• Follow the on-screen instructions to complete the installation.

Step 3: Install OpenJDK

• Once Homebrew is installed, you can use it to install the latest version of OpenJDK:
• Open the Terminal run the following command:

brew install openjdk

• Homebrew will download and install the latest version of OpenJDK.

Step 4: Verify the Installation

• To confirm that OpenJDK has been installed successfully, check the version:

java -version

• You should see output showing the installed version of OpenJDK, such as:

openjdk version "21.0.1" 2025-01-01

OpenJDK Runtime Environment (build 21.0.1+12)

OpenJDK 64-Bit Server VM (build 21.0.1+12, mixed mode)

Step 5: Set JAVA_HOME (Optional)

• Some applications require the JAVA_HOME environment variable to be set. Here’s how you can set it:
• Open the Terminal and edit your shell configuration file. If you are using zsh (default shell on macOS), run:

nano ~/.zshrc

• Add the following line to the file:

export JAVA_HOME="$(brew --prefix openjdk)/libexec/openjdk.jdk/Contents/Home"

• Save the file (press Ctrl + O, then Enter, and Ctrl + X to exit).
• Apply the changes by running:

source ~/.zshrc

• Verify the JAVA_HOME variable:

echo $JAVA_HOME

• This should display the path to your OpenJDK installation.

Method 2: Manual Installation

If you prefer not to use Homebrew, you can manually download and install OpenJDK from the official website:

Step 1: Download OpenJDK

• Visit the official OpenJDK website.
• Download the macOS .tar.gz file for your desired version.

Step 2: Extract the File

• Double-click the downloaded file to extract it.

Step 3: Move the Folder

• Open Terminal and run:

sudo mv jdk-21.jdk /Library/Java/JavaVirtualMachines/

Replace jdk-21.jdk with your actual folder name if different.

Step 4: Verify Installation

java -version

Step 5: Set JAVA_HOME

• Open your shell configuration file:

nano ~/.zshrc

• Add:

export JAVA_HOME="/Library/Java/JavaVirtualMachines/jdk-21.jdk/Contents/Home"

• Apply the changes:

source ~/.zshrc

• Verify:

echo $JAVA_HOME