Manage multiple java versions on the mac from the fish shell

setjdk.fish

function setjdk
  if test -n "$JAVA_HOME"
    removeFromPath "$JAVA_HOME/bin"
  end
  if test "$argv[1]" = "-t"
    set -l POSSIBLE_JAVA_HOME (/usr/libexec/java_home -V 2>&1 >/dev/null | grep $argv[2] | awk -F '\t' '{print $3}')
    if test -d "$POSSIBLE_JAVA_HOME"
      set -gx JAVA_HOME $POSSIBLE_JAVA_HOME
      set -gx PATH $JAVA_HOME/bin $PATH
    else
      echo "Unable to find any JVMs matching version \""$argv[2]"\"."
    end
  else
    set -gx JAVA_HOME (/usr/libexec/java_home -v $argv[1])
    set -gx PATH $JAVA_HOME/bin $PATH
  end
end

function removeFromPath
  set -l idx 0
  for x in (seq (count $PATH))
    if test "$argv[1]" = "$PATH[$x]"
      set idx $x
    end
  end
  if test $idx -gt 0
    set -e PATH[$idx]
  end
end

USAGE:

The output of the command gives you the parameter you supply to the script:
/usr/libexec/java_home -V

Will output the JDK version for you to select:

Matching Java Virtual Machines (7):
17.0.2, x86_64: "OpenJDK 17.0.2" /Library/Java/JavaVirtualMachines/Openjdk-17.0.2.jdk/Contents/Home
17.0.2, x86_64: "Java SE 17.0.2" /Library/Java/JavaVirtualMachines/jdk-17.0.2.jdk/Contents/Home
16, x86_64: "Java SE 16" /Library/Java/JavaVirtualMachines/jdk-16.jdk/Contents/Home
15.0.1, x86_64: "Java SE 15.0.1" /Library/Java/JavaVirtualMachines/jdk-15.0.1.jdk/Contents/Home
14.0.1, x86_64: "Java SE 14.0.1" /Library/Java/JavaVirtualMachines/jdk-14.0.1.jdk/Contents/Home
11.0.10, x86_64: "Java SE 11.0.10" /Library/Java/JavaVirtualMachines/jdk-11.0.10.jdk/Contents/Home
1.8.0_251, x86_64: "Java SE 8" /Library/Java/JavaVirtualMachines/jdk1.8.0_251.jdk/Contents/Home

Currently you supply the first version text to select the JDK you want to use (or matching).

setjdk 17.0.2

The script has been enhanced to work with the text description, the reason being that you can have multiple same versions from different vendors, so how do you select which version of 17.0.2 you would like? Therefore the script now accepts an option (-t) allowing you supply the text description:

setjdk -t "OpenJDK 17.0.2"

or say

setjdk -t "Java SE 17.0.2"

Now you will get the exact version/vendor JDK. So the script operates as previously but with additional flag -t if required.