In a certain situation, I'd like my app to be able to "fake" an incoming SMS on the user's device, as a sort of notification. This would save me money when I'd normally use Twilio to send a text to my users but I know they already have my app. Is there any way to do this? I imagine it would have something to do with Intents and Content Providers but I don't really know where to start.
To clarify: I'm not new to Android and I do respect all of the normal Notification methods. However, my app will have an opt-in for text messages and I'd like to be able to trigger them for free rather than paying for it. This is for SMS-specific uses and not as a substitute for a normal Notification.
Yes (although I really don't support doing this) it is, in theory possible by creating and broadcasting the proper intent. Specifically, they android.provider.Telephony.SMS_RECEIVED intent will be received by anybody who is listening for SMS messages, including the default SMS application. This will in turn cause the notification to be displayed.
All of that said, I've only ever done this in a custom version of Android from within the system process. I'm really not sure if a generic application can do this (in fact, I kinda doubt it). The other caveat is that you will need to formulate your data into PDU's which represent the binary data format of an SMS message. You can look this up, but it's nontrivial.
A far better approach would be to simply have your application display a notification in the tray, the way well behaved applications are supposed to notify the users of events. Take a look at the Notification class.