hi im currently creating an android app through which i have to make money transfers such as debit card ,credit card payment or net banking so how should i incorporate payment gateways of banks into my app..... for example im constructing app similar to flipkart or amazon does! i have done all but i dont know to invoke api or code to create transactions!!!

I am not a that much big expert over this one but I would say at first what can do is choose the payment gatewa you want to put over to your app and then try contacting with them I am sure they will guide you with the process of putting down their payment gateway over their app !