Add partner repository:

$ sudo apt-get purge openjdk*

Update the source list:

$ sudo add-apt-repository "deb http://archive.canonical.com/ lucid partner"
$ sudo apt-get update
$ sudo apt-get install sun-java6-jre sun-java6-plugin

Install Sun’s Java packages:

$ sudo update-alternatives -config java

Confirm that your system is configured properly for Sun’s JRE (by checking the java version):

$ java -version

JDK 8

You can use WebUpd8 PPA (this will download the required files from Oracle and install JDK 8):

$ sudo apt-add-repository ppa:webupd8team/java
$ sudo apt-get update
$ sudo apt-get install oracle-java8-installer

Also ensure your JAVA_HOME variable has been set to /usr/lib/jvm/java-8-oracle.

For this you can use the following command (see step 3 of Manual Install to see how to make it permanent):

$ export JAVA_HOME=/usr/lib/jvm/java-8-oracle

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