Intents and Receivers
You have learned many of the techniques for designing activities. Thanks to the preceding chapter, you now also know about the lifecycle of an activity: when and how it starts, pauses, and ends.
All of the examples presented so far have consisted of just one activity. But if you remember the early part of the book, you will recall that I said Android’s architecture was built around the assumption that activities are cheap, easy to create and destroy, and should be plentiful to help build out the capabilities of any application you might wish to build. Activities, in the plural.
Each of our example applications, from button counters to phone dialers, has used a single activity to display its functionality (with ...