Step #1: Install Capability to Manage Repositories
python-software-properties allows for easy management of your distribution and independent repositories:

sudo apt-get install python-software-properties

Step #2: Add the WebUpd8 Team Personal Package Archive (PPA)
Add the PPA:

sudo apt-add-repository ppa:webupd8team/java

Step #3: The Installation
As a matter of best practice we’ll update our packages:

sudo apt-get update

then let’s install Oracle Java 8 with the PPA installer:

sudo apt-get install oracle-java8-installer

tep #4: Verify Installation
Now verify that Java is installed and is of version 1.8.x:

java -version

Your result should be similar to:

java version "1.8.0_45"
Java(TM) SE Runtime Environment (build 1.8.0_45-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.45-b02, mixed mode)