Install multiple Java versions and switch between them

March 17, 2022

macOS

Download the tarball from here: https://jdk.java.net/16/

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sudo mv openjdk-16.0.1_osx-x64_bin.tar.gz /Library/Java/JavaVirtualMachines/
cd /Library/Java/JavaVirtualMachines/
sudo tar -xzf openjdk-16.0.1_osx-x64_bin.tar.gz
sudo rm openjdk-16.0.1_osx-x64_bin.tar.gz

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echo -n "\nexport JAVA_HOME=`/usr/libexec/java_home -v16`" >> ~/.zprofile

source ~/.zprofile

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java -version

/usr/libexec/java_home -v16 gives you the version specific path. If you wanted to use a different JDK version, say 17, then you'd update JAVA_HOME and set it to /usr/libexec/java_home -v17

Ubuntu Linux

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# java -version

openjdk version "1.8.0_312"
OpenJDK Runtime Environment (build 1.8.0_312-8u312-b07-0ubuntu1~20.04-b07)
OpenJDK 64-Bit Server VM (build 25.312-b07, mixed mode)

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sudo apt install -y openjdk-17-jdk

update-java-alternatives --list

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java-1.11.0-openjdk-amd64      1111       /usr/lib/jvm/java-1.11.0-openjdk-amd64
java-1.17.0-openjdk-amd64      1711       /usr/lib/jvm/java-1.17.0-openjdk-amd64
java-1.8.0-openjdk-amd64       1081       /usr/lib/jvm/java-1.8.0-openjdk-amd64

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# sudo update-java-alternatives --set /path/to/java/version
sudo update-java-alternatives --set /usr/lib/jvm/java-1.17.0-openjdk-amd64

Check version with java -version and you'll see the new one

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openjdk version "17.0.2" 2022-01-18
OpenJDK Runtime Environment (build 17.0.2+8-Ubuntu-120.04)
OpenJDK 64-Bit Server VM (build 17.0.2+8-Ubuntu-120.04, mixed mode, sharing)

Update the $JAVA_HOME env var

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export JAVA_HOME="$(jrunscript -e 'java.lang.System.out.println(java.lang.System.getProperty("java.home"));')"

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export JAVA_HOME='/usr/lib/jvm/java-1.17.0-openjdk-amd64'
export PATH=$PATH:$JAVA_HOME/bin