Java version switcher for Ubuntu

swapJava

#!/bin/bash
# Swaps between java versions
# 
# Execute using the source or '.' command to set environment correctly
#
# to install alternatives after unpacking oracle java tar at /opt/jdk1.8.0_202/ execute
# sudo sh -c 'for bin in /opt/jdk1.8.0_202/bin/*; do update-alternatives --install /usr/bin/$(basename $bin) $(basename $bin) $bin 1500; done'
# 
# to switch manually for individual bins execute
# sudo update-alternatives --config java

VERSION=$1

if [ -z "$VERSION" ]; then
    echo "ERROR: specify Java version to be 8 or 11."
    exit 1
fi

echo "Activating java version" $VERSION

if [ $VERSION -eq 11 ]; then
    sudo sh -c 'for bin in /opt/jdk-11.0.4/bin/*; do update-alternatives --set $(basename $bin) $bin; done'
    export JAVA_HOME="/opt/jdk-11.0.4/"

elif [ $VERSION -eq 8 ]; then
    sudo sh -c 'for bin in /opt/jdk1.8.0_202/bin/*; do update-alternatives --set $(basename $bin) $bin; done'
    export JAVA_HOME="/opt/jdk1.8.0_202/"
else
    echo "ERROR: unsupported version specified:" $VERSION
    exit 1
fi