To get a list of your installed Java platforms, run the following command from the terminal:
sudo update-alternatives --config java
This will give you a list output similar to this:
There are 2 choices for the alternative java (providing /usr/bin/java).
Selection Path Priority Status
---------------------------------------------------------------------------------------------
0 /usr/lib/jvm/java-8-oracle/jre/bin/java 1081 auto mode
*1 /usr/lib/jvm/java-7-openjdk-i386/jre/bin/java 1071 manual mode
2 /usr/lib/jvm/java-8-oracle/jre/bin/java 1081 manual mode
Press enter to keep the current choice[*], or type selection number:
In this case, the Open JDK 6 version is running. To switch to the Open JDK version 7, you would select option 1 at the prompt and press the Enter key.
You will now be running the OpenJDK 7 version. No other changes will be needed to switch your Java versions.
