Choose Java Alternative Version :
When we have got multiple versions of Java installed, we can choose which one you want to use by running the update-alternatives command.
Running below command shows a list of installed Java JDKs and JREs allowing one to be selected as the default that is used when java needs to be executed.
$ sudo update-alternatives --config java
There are 2 choices for the alternative java (providing /usr/bin/java).
Selection Path Priority Status
------------------------------------------------------------
0 /usr/lib/jvm/java-6-openjdk/jre/bin/java 1061 auto mode
1 /usr/lib/jvm/java-6-openjdk/jre/bin/java 1061 manual mode
* 2 /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java 1051 manual mode
Press enter to keep the current choice[*], or type selection number: 2
To choose a default javac compiler, run the following command.
$ sudo update-alternatives --config javac
If we prefer to use a gui instead of the command line, we can execute galternatives instead and define the default versions of software with the following dialog.
$ sudo galternatives
