Java

• Java binaries are installed at:
• Compiler: /usr/lib/jvm/default/bin/javac
• Runtime: /usr/lib/jvm/default/bin/java (or default-runtime)
• Alternatively you can invoke the symlink /usr/bin/java

Brew (MacOS)

• openjdk is keg-only

brew install openjdk
sudo ln -sfn \
  /opt/homebrew/opt/openjdk/libexec/openjdk.jdk \
  /Library/Java/JavaVirtualMachines/openjdk.jdk

Pacman (Archlinux)

• Packages
• jdk-openjdk
• openjdk-doc
• openjdk-src

pacman -S "jdk11-openjdk" "openjdk11-doc" "openjdk11-src"

# Show installed JDKs
archlinux-java status

# Show default JDK
archlinux-java get

# Change default JDK
archlinux-java set "java-17-openjdk" # create symlink /usr/lib/jvm/default -> /usr/lib/jvm/java-17-openjdk

Apt (Debian)

# Show java locations
sudo update-java-alternatives -l

## If not, java must be using another jdk, then:
sudo update-alternatives --config java # Java executor
sudo update-alternatives --config javac # Java compiler

Setup Java Home

• There's no need to set JAVA_HOME if the binaries are already in your $PATH

sudo vim "/etc/environment"
JAVA_HOME="/usr/lib/jvm/default"
JAVA_HOME="/usr/lib/jvm/java-11-amazon-corretto"
JAVA_HOME="/usr/lib/jvm/java-16-openjdk"
source "/etc/environment" # update the current terminal
echo "$JAVA_HOME"

# Or...
export JAVA_HOME=$(readlink -f /usr/bin/javac | sed "s:/bin/javac::")