Change Java HOME runtime on OS X

jvm.sh

#!/usr/bin/env bash
#
# Resources:
# 	- http://superuser.com/questions/490425/how-do-i-switch-between-java-7-and-java-6-on-os-x-10-8-2
#

JAVA_VMS="/Library/Java/JavaVirtualMachines"

#######################
# List available jdks #
######################
function list_versions {
	echo "Available jdk versions are:"
	for version  in $(ls -1  ${JAVA_VMS} | sed 's/.jdk//g' | sed 's/jdk//g' | tr "\n" " "); do
		echo "  ${version}"
	done
}

######################
# Use a specific jdk #
#####################
function use_version {
	version="jdk${1}.jdk"
	if [[ "$(ls  -1 ${JAVA_VMS} | grep -E "${version}" | wc -l )" -eq 0 ]]; then
		echo "No such version \`$1\` in the JavaVirtualMachines directory"
		return
	fi

	path=$PATH
	if [[ "$(echo $PATH | grep -E "${JAVA_VMS}" | wc -l | awk '{print $1}')" -eq 1 ]]; then
		path=$(echo $PATH | tr ":" "\n" | grep -v "${JAVA_VMS}" | tr "\n" ":")
	fi

	# remove trailing ":"
	if [ "${path:(${#path}-1):1}" = ":" ]; then
		path=${path%?}
	fi

	# setup java paths
	java_home_dir="${JAVA_VMS}/${version}/Contents/Home"
	java_bin_dir="${java_home_dir}/bin"

	# /usr/libexec/java_home -v $1 --exec
	export JAVA_HOME=$java_home_dir
	export PATH=$JAVA_HOME/bin:$path

	cat <<EOF
Updated \$JAVA_HOME and \$PATH to following values:
	JAVA_HOME=$JAVA_HOME
	PATH=$PATH"
EOF
}

function remove_version {
	version="jdk${1}.jdk"
	if [[ "$(ls  -1 ${JAVA_VMS} | grep -E "${version}" | wc -l )" -eq 0 ]]; then
		echo "No such version \`$1\` in the JavaVirtualMachines directory"
		return
	fi

	dir="${JAVA_VMS}/${version}"
	echo "Attempting to remove the jdk version $1"
	sudo rm -rf $dir
}

################
# Print usage #
###############
function print_usage {
	# run as jvm bash alias with .
	arg=$0
	if [[ "$arg" = "-bash" ]]; then
		arg="jvm"
	fi

	cat <<EOF
Usage: $(basename $arg) OPTION [\$ARG ...]

OPTIONS
	list            List available versions
	remove \$VERSION Remove the specified version
	use \$VERSION    Specify the version to use
	help            Print this help
EOF
}

###################
# Read user input #
###################
function read_user_input {
	for el in "$@"; do
		if [[ "$el" = "list" ]]; then
			list_versions
			return
		elif [[ "$el" = "remove" ]]; then
			remove_version $2
			return
		elif [[ "$el" = "use" ]]; then
			use_version $2
			return
		elif [[ "$el" = "help" ]]; then
			print_usage $@
			return
		fi
	done

	print_usage
}

read_user_input "$@"

Running the script

You will need to source the script when running:

. jvm.sh use $version

or

source . jvm.sh use $version

To be able to export the values from the script to the current user environment.
These changes are not permanent but only available for the current user environment.

Available commands:

• list List all available jdk versions from the JavaVirtualMachines directory
• use The version to use

Expected requirements

An OS X environment

Added "remove" function.
Creating a bash alias i.e.

alias jvm=". jvm.sh"

Comes in handy and no need source . the script manually.