How to create app widget in android?

What is app widget?

App Widgets are miniature application views that can be embedded in other applications (such as the Home screen) and receive periodic updates. These views are referred to as Widgets in the user interface, and you can publish one with an App Widget provider. An application component that is able to hold other App Widgets is called an App Widget host. The screenshot below shows the Music App Widget.


To create an App Widget, you need the following:

AppWidgetProviderInfo object

Describes the metadata for an App Widget, such as the App Widget's layout, update frequency, and the AppWidgetProvider class. This should be defined in XML.

AppWidgetProvider class implementation

Defines the basic methods that allow you to programmatically interface with the App Widget, based on broadcast events. Through it, you will receive broadcasts when the App Widget is updated, enabled, disabled and deleted.

View layout

Defines the initial layout for the App Widget, defined in XML.

Additionally, you can implement an App Widget configuration Activity. This is an optional Activity that launches when the user adds your App Widget and allows him or her to modify App Widget settings at create-time.
The following sections describe how to setup each of these components.

Declaring an App Widget in the Manifest

First, declare the AppWidgetProvider class in your application's AndroidManifest.xml file. For example:

<receiver android:name="ExampleAppWidgetProvider" >
    <intent-filter>
        <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
    </intent-filter>
    <meta-data android:name="android.appwidget.provider"
               android:resource="@xml/example_appwidget_info" />
</receiver>

The <receiver> element requires the android:name attribute, which specifies the AppWidgetProvider used by the App Widget.
The <intent-filter> element must include an <action> element with the android:name attribute. This attribute specifies that the AppWidgetProvider accepts the ACTION_APPWIDGET_UPDATE broadcast. This is the only broadcast that you must explicitly declare. The AppWidgetManager automatically sends all other App Widget broadcasts to the AppWidgetProvider as necessary.
The <meta-data> element specifies the AppWidgetProviderInfo resource and requires the following attributes:

• android:name - Specifies the metadata name. Use android.appwidget.provider to identify the data as the AppWidgetProviderInfo descriptor.
• android:resource - Specifies the AppWidgetProviderInfo resource location.

 credits:developer.android.com