update java ubuntu code example

Example 1: update ubuntu

sudo apt update && sudo apt upgrade -y
#or use it seperately
sudo apt update
sudo apt upgrade
#you make wanna run below command to remove unwanted
#and free up some space
sudo apt autoremove

Example 2: install openjdk 8 sdk on ubuntu

sudo apt-get install openjdk-8-jdk

Example 3: install java ubuntu

sudo apt install default-jre