Using Android's Fingerprint Scanner for Application

Fingerprint scanner is not a feature in Android (Now available on Android M).

So each company as Samsung, Motorola, HTC create is own API and SDK to access to fingerprint sensor.

For instance Samsung provide a SDK http://developer.samsung.com/galaxy#pass

Pass SDK allows you to use fingerprint recognition features in your application. With Pass SDK, you can provide reinforced security, since you can identify whether the current user actually is the authentic owner of the device.

If you want to enroll multiple users and check users in your app, it's not possible with Samsung device. You could only check owner of device.

I don't know SDK of other companies.

UPDATE

Android M have new FingerPrint API: https://developer.android.com/about/versions/marshmallow/android-6.0.html#fingerprint-authentication

Android M preview introducing FingerPrint scanner API. You can checkout example for this here : https://github.com/googlesamples/android-FingerprintDialog/