show, list or set java version for current shell, mac only

jv.sh

# show, list or set java version for current shell
# usage: jv; jv -l; or jv 8
jv() {
  local d v="$1"
  if [ $# -ge 1 ]; then
    [ -z "${v#-[lLV]}" ] && { /usr/libexec/java_home -V; return; }
    [ -z "${v##-*}" ] && { /usr/libexec/java_home "$@"; return; }
    [ ${#v} -eq 1 -a -z "${v#[0-8]}" ] && v="1.$v"
    [ -n "$v" ] && d=$(/usr/libexec/java_home -v "$v") && \
    export JAVA_HOME="$d"
  fi
 
  [ -n "$JAVA_HOME" ] && echo "JAVA_HOME: $JAVA_HOME"
  java -version
}