How to properly install Temurin JDK with update-alternatives

You can use the Adoptium Debian / Ubuntu repository

1. Add the Eclipse Adoptium GPG key

   wget -O - https://packages.adoptium.net/artifactory/api/gpg/key/public | sudo apt-key add -
   

2. Add the Eclipse Adoptium apt repository

   echo "deb https://packages.adoptium.net/artifactory/deb $(awk -F= '/^VERSION_CODENAME/{print$2}' /etc/os-release) main" | sudo tee /etc/apt/sources.list.d/adoptium.list
   

3. Install the Temurin version you require

   sudo apt update # update if you haven't already
   sudo apt install temurin-21-jdk
   

4. Configure the default version

   sudo update-alternatives --config java