Awesome Script for Changing Java Versions

#jvm

#profile

#jdk

#java

#bash

#switch jdk

I noticed this post
https://coderwall.com/p/2klgtg
and decided that I should put up the way that I like to change my java versions.

I originally took part of this from stack overflow somewhere but have tweaked it a little to work better.

Basically I just add the following snippets to my Mac OSX ~/.profile file.

#!/bin/bash

alias java_ls='/usr/libexec/java_home -V 2>&1 | grep -E "\d.\d.\d_\d\d" | cut -d , -f 1 | colrm 1 4 | grep -v Home'

function java_use() {
    export JAVA_HOME=$(/usr/libexec/java_home -v $1)
    export PATH=$JAVA_HOME/bin:$PATH
    java -version
}

and then reloaded my profile by running source ~/.profile in terminal

So how do i use it?

Well just execute
java_ls
at the terminal and you will get a full listing of the available installed java_home's on your machine, like this ...

tom@Toms-iMac:~/dev$ java_ls
1.7.0_25
1.7.0_21
1.7.0_13
1.6.0_43-b01-447
1.6.0_43-b01-447

But how do I then change my current java version?
Well just simply execute

java_use java_version

For example if you wanted to switch to use java jdk 1.6 you would simply write

java_use 1.6

or if you wanted to switch to java jdk 1.7.0_21 you would simply write

java_use 1.7.0_21.

You could also have used just java_use 1.7 if you don't mind it picking up the most recent patch revision of java 1.7 you have installed.

Running this command will also output the java -version at the end so you know which jdk you're working with, like this ...

tom@Toms-iMac:~/dev$ java_use 1.7
java version "1.7.0_25"
Java(TM) SE Runtime Environment (build 1.7.0_25-b15)
Java HotSpot(TM) 64-Bit Server VM (build 23.25-b01, mixed mode)

So how does it work?

There is a java_home executable which allows you to list the available/installed java home directories and show/set the current java_home. The alias does some nice massaging of it's output to make it look better in the results. It also can take a parameter to allows you to set that as your java home. Basically it's awesome and it works.

Why is this better than other solutions?