FFT based simple Spectrum Analyzer with Source Code

i am writing this blogpost to pay homage to my alma mater... i was not at my level best to understand all aspects of Electonics & Telecommunication, the Microprocessor, the Digital Communication, the Digital Signal processing as taught by my professors... however, after so many years while playing around with different software, i understand how valuable was their contribution to make me an engineer. i remember, how important was the lesson of digital communication, and digital signal processing taught by Dr. T.K.Sen... i remember how important was the lesson of Microprocessor taught by A.R.... i remember how important was the lectures of Maths during our engineering course... i remember how important were the concepts of Fourier Transformation, FFT, DFT, Laplace Transformation, Matrix algebra and Complex Algebra...Hats off to all those professors who in spite of all odds helped a small town boy see the outer world...

You can install this FFT based simple Spectrum Analyzer with a sampling frequency of 8 KHz and audio encoding as 16 bit PCM from google play at https://play.google.com/store/apps/details?id=com.somitsolutions.android.spectrumanalyzer
i was so excited when i finished the coding part (of course with the help of Google...) and saw its working on a real device...

here are the a screenshot i have taken from an Android device...

and here (https://gitlab.com/som.mukhopadhyay/FFTBasedSpectrumAnalyzer) goes the source code which may help someone interested in Android...