See these pages for more details on how to install Java:
https://help.ubuntu.com/community/Java
http://docs.oracle.com/javase/8/docs/technotes/guides/install/linux_jdk.html

Download the JDK/JRE: http://www.oracle.com/technetwork/java/javase/downloads/index.html

Extract the file "jdk-8u111-linux-x64.tar.gz" in the folder you want to install Java: /opt/jdk1.8.0_111

$ sudo tar -xf jdk-8u111-linux-x64.tar.gz -C /opt/

Change the folder permissions:

$ sudo chmod -R 755 /opt/jdk1.8.0_111
$ sudo chown -R mtitek /opt/jdk1.8.0_111
$ sudo chgrp -R mtitek /opt/jdk1.8.0_111

Setup the environment variables JAVA_HOME and PATH:

• Open the file ".profile":

  $ vi ~/.profile
  

• Append the following lines:

  export JAVA_HOME=/opt/jdk1.8.0_111
  export PATH=$JAVA_HOME/bin:$PATH
  

• Reload the file ".profile":

  $ source ~/.profile
  

• Verify the environment variables:

  $ echo $JAVA_HOME
  $ echo $PATH
  

Locate the default java program file:

$ which java
/opt/jdk1.8.0_111/bin/java