How to install Java 8 in Ubuntu/mint

For installing java 8 in your system, you need to executes the following commands with sudo permission.

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

How to check , which version is installed in my system?

Its very simple, you can simple the following command on your terminal/cmd to see the latest java installed version

javac -version

Read for more Info: 
http://tipsonubuntu.com/2016/07/31/install-oracle-java-8-9-ubuntu-16-04-linux-mint-18/