How to install Virtual box in Kali linux rollling

I made Kali linux (rolling) as the primary OS for one of my systems.The problem i faced was in installation of virtual box. Regular method i.e. apt-get install virtualbox , was not working.

After doing my research ,i found this method working for me... S
Sharing here so that someone in a similar situation as mine can use it.

1. Add the following line to /etc/apt/sources.list
   deb http://mirror.nus.edu.sg/kali/kali kali-rolling main non-free contrib
2. do the following, second command might take some time, let it finish completely.
   apt-get update
   apt-get dist-upgrade
3. Once the upgrade is completed , run
   apt-get install virtualbox
   

CYB3RTR0N