Hello World Widget in Android

In this exercise, a dummy home screen app widget will be described; to show the

simpliest element of a ndroid app widget.

- Create a new project of android application as normal, HelloWidget.

- Modify AndroidManifest.xml to have a receiver, with name of "HelloWidgetProvider", under Appliation.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="com.exercise.HelloWidget"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon" android:label="@string/app_name">
  <activity android:name=".HelloWidget"

            android:label="@string/app_name">
      <intent-filter>
          <action android:name="android.intent.action.MAIN" />
          <category android:name="android.intent.category.LAUNCHER" />

      </intent-filter>
  </activity>
 <receiver android:name="HelloWidgetProvider" >
    <intent-filter>
        <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />

    </intent-filter>
    <meta-data android:name="android.appwidget.provider"
     android:resource="@xml/hellowidgetproviderinfo" />
 </receiver>
</application>

<uses-sdk android:minSdkVersion="4" />

</manifest>

The element requires the android:name attribute, which specifies the AppWidgetProvider used by the App Widget.

The element must include an element with the android:name attribute. This attribute specifies that the AppWidgetProvider accepts the ACTION_APPWIDGET_UPDATE broadcast.

The 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.

- Create a new folder /res/xml, create a new hellowidgetproviderinfo.xml

 

<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
android:minWidth="146dp"
android:minHeight="72dp"
android:updatePeriodMillis="10000"
android:initialLayout="@layout/hellowidget_layout"
>
</appwidget-provider>

It define the AppWidgetProviderInfo object in an XML resource using a single , include the essential qualities of an App Widget, such as its minimum layout dimensions, its initial layout resource, how often to update the App Widget, and (optionally) a configuration Activity to launch at create-time.

- Create a layout file /res/layout/hellowidget_layout.xml
 

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"

/>
</LinearLayout>

It's the layout of the widget. In this dummy exercisse, just copy the content of the auto-generated layout, main.xml.

- Create a class HelloWidgetProvider.java extends AppWidgetProvider. With nothing inside.

package com.exercise.HelloWidget;

import android.appwidget.AppWidgetProvider;

public class HelloWidgetProvider extends AppWidgetProvider {

}

It do nothing at all. Now you can build and Install the application as normal, then close it after started.
It's not own target in this exercise.

- Add the HelloWidget on Home Screen. It's
a dummy widget without any function, just show how to create a app widget.