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| <p>Contains high-level classes encapsulating the overall Android application model.</p> |
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| <p>An Android application is defined using one or more of Android's four core application |
| components. Two such application components are defined in this package: {@link |
| android.app.Activity} and {@link android.app.Service}. The other two components are from the {@link |
| android.content} package: {@link android.content.BroadcastReceiver} and {@link |
| android.content.ContentProvider}.</p> |
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| <p>An {@link android.app.Activity} is an application component that provides a screen with which |
| users can interact in order to do something, such as dial the phone, take a photo, send an email, or |
| view a map. An activity can start other activities, including activities that live in separate |
| applications.</p> |
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| <p>A {@link android.app.Service} is an application component that can perform |
| long-running operations in the background without a user interface. For example, a service |
| can handle network transactions, play music, or work with a content provider without the user being |
| aware of the work going on.</p> |
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| <p>The {@link android.app.Fragment} class is also an important part of an application's |
| design—especially when designing for large screen devices, such as tablets. A fragment defines |
| a distinct part of an activity's behavior, including the associated UI. It has its own lifecycle |
| that is similar to that of the activity and can exist alongside other fragments that are embedded in |
| the activity. While an activity is running, you can add and remove fragments and include each |
| fragment in a back stack that's managed by the activity—allowing the user to navigate |
| backwards through the fragment states, without leaving the activity.</p> |
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| <p>This package also defines application utilities, such as dialogs, notifications, and the |
| action bar.</p> |
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| <p>For information about using some the classes in this package, see the following |
| documents: <a href="{@docRoot}guide/topics/fundamentals/activities.html">Activities</a>, <a |
| href="{@docRoot}guide/topics/fundamentals/services.html">Services</a>, <a |
| href="{@docRoot}guide/components/fragments.html">Fragments</a>, <a |
| href="{@docRoot}guide/topics/ui/actionbar.html">Using the Action Bar</a>, <a |
| href="{@docRoot}guide/topics/ui/dialogs.html">Creating Dialogs</a>, and <a |
| href="{@docRoot}guide/topics/ui/notifiers/index.html">Notifying the User</a>.</p> |
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