Android Payment Integration App Development

I have the concept and basic screen sketches ready; I now need the actual Android application coded from the ground up, complete with a seamless payment flow. The app is Android-only for the moment, so everything should be built and tested in Android Studio using Kotlin or Java—whichever you feel delivers the cleanest, most maintainable result. The critical requirement is a fully functioning payment gateway connection. I’m open to Stripe, PayPal, or any other widely used PCI-compliant service, as long as test transactions run smoothly and the code clearly returns success or failure states that I can extend later. Deliverables • Complete Android source code with clear comments • Payment service fully integrated and verified with test cards • Installable APK for review on physical devices • Brief setup guide so I can build and run the project locally Keep the architecture modular because I may plug in social features down the road. Smooth performance, quick screen loads, and rock-solid payment handling are the benchmarks for acceptance.