How to run multiple versions of java in Ubuntu linux

Hi,

 First install the two version of java by issuing the commands.

apt-get install openjdk-6-jre
apt-get install openjdk-7-jre

It will install the two version of java but the last installed version can be used by default on the system.


The installation path will be

/usr/lib/jvm/java-7-openjdk-i386
/usr/lib/jvm/java-6-openjdk-i386

By default the java bin path /usr/bin/java is linked to the file /etc/alternatives/java which is linked to /usr/lib/jvm/java-7-openjdk-i386/jre/bin/java(if it is installed first). Other wise the link will be to /usr/lib/jvm/java-6-openjdk-i386/jre/bin/java

To use a different version of java on the same ubuntu machine, we need to export the java home path using the command

export JAVA_HOME=/usr/lib/jvm/java-7-openjdk-i386/

If you need to make it permenant you need to add this in the .bashrc file.


Other wise there is another command which will help to change the java version.

which is

update-alternatives --config java
which will list the installed java versions

update-alternatives --config java
There are 3 choices for the alternative java (providing /usr/bin/java).

  Selection    Path                                           Priority   Status ------------------------------------------------------------
  0            /usr/lib/jvm/java-6-openjdk-i386/jre/bin/java   1061      auto mode
  1            /usr/lib/jvm/java-6-openjdk-i386/jre/bin/java   1061      manual mode
* 2            /usr/lib/jvm/java-7-openjdk-i386/jre/bin/java   1051      manual mode
  3            /usr/lib/jvm/java-7-oracle/jre/bin/java         1         manual mode

If you want to use java version 1.6 choose the first one and enter it will change the binary path of the java to the new one.

Regards
Syamkumar