In this example we will be making a simple Android application which will be integrated with PayPal service, just to show how it is done through PayPal developer sandbox account.
First we will need a new Android project in Android Studio, and then we will to create an PayPal developers account. On the following link is simple step-by-step tutorial how to create the account:
https://developer.paypal.com/docs/classic/lifecycle/sb_create-accounts/
After the creating the account, very important is to see you BUSINESS account for testing, because from there we will need the client_id for receiving payment, and it will look something like this:
Android for beginners 