Java Version Switcher

javaswitch.sh

#!/usr/bin/env bash

declare -A JDKS

JDKS[8]="/usr/lib/jvm/jdk1.8.0_251"
JDKS[11]="/usr/lib/jvm/jdk-11.0.9"
JDKS[14]="/usr/lib/jvm/jdk-14.0.1"
JDKS[16]="/usr/lib/jvm/jdk-16.0.2"

if [ "$#" -ne 1 ]; then
        echo "pass one parameter, 8 or 11, for the java version to use"
fi

## deactivate previous
if [ -n "$ZSH_VERSION" ]; then
   # assume Zsh
   for key value in ${(kv)JDKS}; do
	echo "$value"
	sudo update-alternatives --remove "java" "${value}/bin/java"
	sudo update-alternatives --remove "javac" "${value}/bin/javac"
   done
elif [ -n "$BASH_VERSION" ]; then
   # assume Bash
   for k in "${!JDKS[@]}"; do
	echo "${JDKS[$k]}"
	sudo update-alternatives --remove "java" "${JDKS[$k]}/bin/java"
	sudo update-alternatives --remove "javac" "${JDKS[$k]}/bin/javac"
   done
else
   # assume something else
   echo "could not determine your bash"
   exit 0
fi

export JAVA_HOME="${JDKS[$1]}"
echo "switching java home to $JAVA_HOME"
sudo update-alternatives --install "/usr/bin/java" "java" "$JAVA_HOME/bin/java" 100
sudo update-alternatives --install "/usr/bin/javac" "javac" "$JAVA_HOME/bin/javac" 100