What makes an android application?

The following six components provide the building blocks of any android application:

1. Activity: You application's Presentation layer. Evey screen of your application will be an extension of activity class. Activities uses Views for GUI that display information and respond to user action. In terms of desktop application, an activity is equivalent to a form.

2. Service: The invisible workers of your application. Service component run in the background, updating data sources and visible activities and triggering notifications. They are used to perform regular processing that’s need to continue even when your application’s activities aren’t active or visible

  

3. Content Provider:  Sharable data sources, used to share and manage application data source. They are preferred means of sharing data across application boundaries . This means that you can configure your own Content Providers to permits access from other applications and use content providers exposed by others to access their stored data. Android include several native content provider that expose useful database like the media stores and contact details.

4. Intent : A inter-process message passing framework. Using intent you can broadcast messages system-wide or to a target activity or service, stating an action have performed. The system will then determine the target(s) that will perform any actions as appropriate.

5. Broadcast receiver: Intent broadcast consumers. If you register a broadcast receiver, your application can listen for broadcast intent that match specific filter criteria. Broadcast receiver will automatically start your application in response to an incoming intent, making them perfect for event driving application.

6. Widgets: Visual application content that can be added to the desktop. A special variation of broadcast receiver, widgets let you create dynamic, interactive component for users to embed in their home screen.

7. Notifications: A user notification framework. It let you to signal user without stealing focus or interrupting their current activity. For example, when a device receive a text message or an incoming call or a file via Bluetooth, it alert the user by flashing lights, making sounds, displaying icon, showing message.

        These are the very basic component of all android application. This post only gives a summarize picture of these component.