They can communicate with other Android components and send notifications to the user.įor example, a broadcast receiver can notify the user via the notification framework in Android.Ī receiver can be registered to listen to system messages and intents.Ī receiver gets notified by the Android system if the specified event occurs.įor example, you can register a receiver for the event that the Android system finished the boot process. If not explicitly defined, Android creates a default application object for your application.Īn activity is the visual representation of an Android application.Īn Android application can have several activities.Īctivities use views and fragments to create their user interface and to interact with the user.Ī service performs tasks without providing an user interface.

It is the last component which is stopped during application shutdown. Android application components ComponentĪn Android application can have one Application class which is instantiated before any other Android component. You can define the following components in your configuration files: Table 8. temperatureconverter import import android.os.Bundle import import import import public class MainActivity extends Activity Īn Android application (app) is a single installable unit which can be started and used independently.Īn Android application consists of configuration files, Java source and resource files.

You access them via an InputStream object.ĭefines the actions which can be used in the toolbar of the application.

XML files with layout descriptions are used to define the user interface for activities and fragments.įiles which define the appearance of your Android application.ĭefines animations in XML for the animation API which allows to animate arbitrary properties of objects over time.Īrbitrary files saved in their raw form. In a separate file, e.g., strings are defined in Used to define strings, colors, dimensions, styles andĪrrays of strings or integers via XML files. Images (e.g., png or jpeg files)or vector drawables or XML files which scale automatically with the density of the Android device The following table gives an overview of the supported resources and their standard folder prefixes.

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