Passing data to activity from threaded service

How can I pass data from a threaded service to the activity that created the servic开发者_StackOverflow社区e?

It's a login scenario. The user enters credentials, the activity starts a service which calls an wcf service to confirm the credentials. When this is done I want the service to tell the activity that the login has succeeded/failed.

You can simply use AsyncTask to perform the login check. It is recommended to show a dialog while performing long work, see the example with progress dialog.