Install Java (OpenJDK) on Linux, macOS and Windows

Which option to pick

Java is specified by Oracle but built by many vendors from the same OpenJDK source: Eclipse Temurin, Microsoft Build of OpenJDK, Amazon Corretto, the distribution’s own packages, and Oracle’s. For development they are interchangeable; pick what your package manager offers. Install a JDK (development kit, includes javac), not a JRE. Choose the newest LTS version (21 at the time of writing, with 25 as the next LTS) unless the project you work on pins another. If you need to juggle several versions, SDKMAN! on Linux and macOS makes switching easy.

Step: Linux

Debian and Ubuntu (default-jdk picks the distribution’s current OpenJDK; use a numbered package to choose):

sudo apt update
sudo apt install default-jdk
sudo apt install openjdk-21-jdk

Fedora and RHEL:

sudo dnf install java-21-openjdk-devel

Or with SDKMAN!, which works on any distribution and manages versions in your home directory:

curl -s "https://get.sdkman.io" | bash
source "$HOME/.sdkman/bin/sdkman-init.sh"
sdk list java
sdk install java 21-tem

Step: macOS

brew install openjdk@21
sudo ln -sfn "$(brew --prefix)/opt/openjdk@21/libexec/openjdk.jdk" /Library/Java/JavaVirtualMachines/openjdk-21.jdk

The symlink is the step Homebrew prints in its caveats; it registers the JDK with macOS so java and /usr/libexec/java_home find it. Alternatively brew install --cask temurin@21 installs Eclipse Temurin as a normal macOS package, or SDKMAN! works exactly as on Linux.

Step: Windows

winget install Microsoft.OpenJDK.21

Or winget install EclipseAdoptium.Temurin.21.JDK, or download the .msi installer from adoptium.net. The installers set JAVA_HOME and add the bin directory to PATH; open a new terminal afterwards.

Check it works

java -version
javac -version

Both should report the same version, for example openjdk 21.0.x. Note that java uses a single dash for -version. A first compile and run:

cat > Hello.java <<'EOF'
public class Hello {
    public static void main(String[] args) {
        System.out.println("hello from java");
    }
}
EOF
java Hello.java

Common problems

• javac: command not found while java works: only a JRE is installed. Install the -jdk or -devel package.
• The wrong version runs when several are installed: on Debian and Ubuntu use sudo update-alternatives --config java (and the same for javac); on macOS set export JAVA_HOME=$(/usr/libexec/java_home -v 21); with SDKMAN! run sdk use java 21-tem.
• Build tools such as Maven or Gradle complain about JAVA_HOME: set it to the JDK directory, for example /usr/lib/jvm/java-21-openjdk-amd64 on Ubuntu, in your shell startup file or Windows environment variables.
• On macOS, java shows a dialog saying no Java runtime is present even after brew install: the symlink step above was skipped.

Official documentation

• OpenJDK: installation
• Eclipse Temurin installation guide
• SDKMAN! installation