Download the best and easy QR Code Reader in the world. Only 1 MB in size and without any ads.
https://play.google.com/store/apps/details?id=com.zakasoft.qrcodereader
To create an app similar to this visit the below link.
https://www.varvet.com/blog/android-qr-code-reader-made-easy/
Zakaria Bin Abdur Rouf 