It is extremely not recommended to use "connectors" from banks in android to external banks, since you would expose the data of your server in the android application (.apk), being able to be decompiled and the data to be accessed.
I recommend that you do as @Piovezan commented, use WebServices!
I'll list some advantages :
1 - More security and stability . (The server security data will not be exposed in the code.)
2 - Abstraction of server security logic (You will make a request and the server will treat).
3 - The webservice Logic can be shared with other services that need these data from your bank (Any application can contact the service and have access to your data)
Some tutorials that can help you:
link
link
link
Good luck!