Is it possible to write an android program that responds to the "knock on the phone in your pocket" event?

Question

Android

Hello.
I accidentally saw an application for the iPhone knocktounlock and now I'm tormented by the question (since I'm not an android developer):
Theoretically, is it possible to write a program that will respond to the "knock on the phone in your pocket" event and send a message to a server on the Internet?
Or is it basically impossible?

Answer 1

Can. But it will take any shaking that fits the pattern of finger tapping as a "knock". Those. a service will be constantly launched that takes accelerometer readings and compares them with a given pattern: short-term accelerations in approximately one direction in the amount of n pieces for a given period of time..

Answer 2

Maybe.