References :

https://source.android.com/source/initializing.html

For Ubuntu >= 15.04 (you need a 64bit version of ubuntu. The website says it recommends 14.04, I am using 16.04. )

sudo apt-get update
sudo apt-get install openjdk-8-jdk

sudo apt-get install git-core gnupg flex bison gperf build-essential \
  zip curl zlib1g-dev gcc-multilib g++-multilib libc6-dev-i386 \
  lib32ncurses5-dev x11proto-core-dev libx11-dev lib32z-dev ccache \
  libgl1-mesa-dev libxml2-utils xsltproc unzip

Configure USB Access. Replace <username> with your username

wget -S -O - http://source.android.com/source/51-android.rules | sed "s/<username>/$USER/" | sudo tee >/dev/null /etc/udev/rules.d/51-android.rules; sudo udevadm control --reload-rules