A while ago, I was developing an Android app, and I wanted to integrate this app with Facebook. I followed the Facebook SDK useless documentation and of-course I faced several problems.
One of these problems was at the beginning of creating the Facebook App, I was asked to enter my "Android App Key Hash". They way for getting this Hash Key is to use the key-store tool, but for some reason the key was not accepted by Facebook.
Other solution for this is to use java code to get the hash