Android™ How to Program, Second Edition

8.3.2. Communicating Data Between a Fragment and a Host Activity

To communicate data between Fragments and a host Activity or the Activity’s other Fragments, it’s considered best practice to do so through the host Activity—this makes the Fragments more reusable, because they do not refer to one another directly. Typically, each Fragment defines an interface of callback methods that are implemented in the host Activity. We’ll use this technique to enable this app’s MainActivity to be notified when the user selects a contact to display, touches an action bar item (, or ), or finishes editing an existing contact or adding a new one.