This example explains the use of app widgets in android. This app widget that displays the GPS coordinates the device.
Algorithm:
1.) Create a new project by File-> New -> Android Project name it GPSAppWidgetExample.
2.) Write following into res/values/strings.xml:
<resources>
<string name="app_name">GPSAppWidgetExample</string>
<string name="hello_world">Hello world!</string>
<string name="menu_settings">Settings</string>
<string name="title_activity_gpsapp_widget_example">GPSAppWidgetExample</string>
<string name="app_info">This widget shows the GPS coordinates of the device's position. The widget refreshes the position in 15 minutes interval</string>
</resources>
3.) Create and write following into res/xml/gpswidgetinfo.xml:
<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
android:minWidth="294dp"
android:minHeight="72dp"
android:updatePeriodMillis="900000"
android:initialLayout="@layout/gpswidget">
</appwidget-provider>
4.) Write following into gpswidget.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="@drawable/back"
android:padding="10dip">
<ImageView
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:src="@drawable/widgeticon"/>
<TextView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/txtInfo"
android:text="Waiting for GPS coordinates..."
android:textColor="#FFFFFFFF"
android:gravity="center_horizontal|center_vertical"/>
</LinearLayout>
</LinearLayout>
5.) Write following into AndroidManifest.xml:
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.gpsappwidgetexample"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="5"
android:targetSdkVersion="15" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".GPSAppWidgetExample"
android:label="@string/title_activity_gpsapp_widget_example" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<receiver android:name=".GPSWidgetProvider">
<intent-filter>
<action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
</intent-filter>
<meta-data android:name="android.appwidget.provider"
android:resource="@xml/gpswidgetinfo" />
</receiver>
<service android:name=".GPSWidgetProvider$GPSWidgetService"></service>
</application>
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
</manifest>
Write following into main.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"
android:padding="10dip">
<ImageView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:src="@drawable/widgeticon"
android:scaleType="fitCenter"/>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center_horizontal"
android:text="@string/app_name"
android:textSize="20dip"
android:textStyle="bold"
android:padding="10dip"/>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center_horizontal"
android:text="@string/app_info"/>
</LinearLayout>
6.) Add two icons back.png and widgeticon.png into your drawable folder.
7.) Run for output.
Steps:
1.) Create a project named GPSAppWidgetExample and set the information as stated in the image.
Build Target: Android 4.0
Application Name: GPSAppWidgetExample
Package Name: com. example. GPSAppWidgetExample
Activity Name: GPSAppWidgetExample
Min SDK Version: 2.0
2.) Open GPSAppWidgetExample.java file and write following code there:
package com.example.gpsappwidgetexample;
import android.app.Activity;
import android.os.Bundle;
public class GPSAppWidgetExample extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
}
3.) Create and Write following into GPSWidgetProvider.java:
package com.example.gpsappwidgetexample;
import java.util.List;
import android.app.PendingIntent;
import android.app.Service;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.location.Address;
import android.location.Criteria;
import android.location.Geocoder;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.IBinder;
import android.widget.RemoteViews;
public class GPSWidgetProvider extends AppWidgetProvider {
@Override
public void onDeleted(Context context, int[] appWidgetIds) {
super.onDeleted(context, appWidgetIds);
}
@Override
public void onDisabled(Context context) {
super.onDisabled(context);
}
@Override
public void onEnabled(Context context) {
super.onEnabled(context);
}
@Override
public void onReceive(Context context, Intent intent) {
super.onReceive(context, intent);
}
@Override
public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
super.onUpdate(context, appWidgetManager, appWidgetIds);
final int N = appWidgetIds.length;
for (int i=0; i<N; i++) {
int appWidgetId = appWidgetIds[i];
Intent intent = new Intent(context, GPSAppWidgetExample.class);
PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, intent, 0);
RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.gpswidget);
views.setOnClickPendingIntent(R.id.txtInfo, pendingIntent);
appWidgetManager.updateAppWidget(appWidgetId, views);
}
context.startService(new Intent(context,GPSWidgetService.class));
}
public static class GPSWidgetService extends Service{
private LocationManager manager = null;
private LocationListener listener = new LocationListener() {
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {}
@Override
public void onProviderEnabled(String provider) {}
@Override
public void onProviderDisabled(String provider) {}
@Override
public void onLocationChanged(Location location) {
AppLog.logString("Service.onLocationChanged()");
updateCoordinates(location.getLatitude(),location.getLongitude());
stopSelf();
}
};
@Override
public IBinder onBind(Intent intent) {
return null;
}
@Override
public void onCreate() {
super.onCreate();
AppLog.logString("Service.onCreate()");
manager = (LocationManager)getSystemService(LOCATION_SERVICE);
}
@Override
public void onStart(Intent intent, int startId) {
super.onStart(intent, startId);
waitForGPSCoordinates();
}
@Override
public void onDestroy() {
stopListening();
AppLog.logString("Service.onDestroy()");
super.onDestroy();
}
public int onStartCommand(Intent intent, int flags, int startId) {
waitForGPSCoordinates();
AppLog.logString("Service.onStartCommand()");
return super.onStartCommand(intent, flags, startId);
}
private void waitForGPSCoordinates() {
startListening();
}
private void startListening(){
AppLog.logString("Service.startListening()");
final Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_COARSE);
criteria.setAltitudeRequired(false);
criteria.setBearingRequired(false);
criteria.setCostAllowed(true);
criteria.setPowerRequirement(Criteria.POWER_LOW);
final String bestProvider = manager.getBestProvider(criteria, true);
if (bestProvider != null && bestProvider.length() > 0) {
manager.requestLocationUpdates(bestProvider, 500, 10, listener);
}
else {
final List<String> providers = manager.getProviders(true);
for (final String provider : providers) {
manager.requestLocationUpdates(provider, 500, 10, listener);
}
}
}
private void stopListening(){
try {
if (manager != null && listener != null) {
manager.removeUpdates(listener);
}
manager = null;
}
catch (final Exception ex) {
}
}
private void updateCoordinates(double latitude, double longitude){
Geocoder coder = new Geocoder(this);
List<Address> addresses = null;
String info = "";
AppLog.logString("Service.updateCoordinates()");
AppLog.logString(info);
try
{
addresses = coder.getFromLocation(latitude, longitude, 2);
if(null != addresses && addresses.size() > 0){
int addressCount = addresses.get(0).getMaxAddressLineIndex();
if(-1 != addressCount){
for(int index=0; index<=addressCount; ++index){
info += addresses.get(0).getAddressLine(index);
if(index < addressCount)
info += ", ";
}
}
else
{
info += addresses.get(0).getFeatureName() + ", " + addresses.get(0).getSubAdminArea() + ", " + addresses.get(0).getAdminArea();
}
}
AppLog.logString(addresses.get(0).toString());
}
catch (Exception e)
{
e.printStackTrace();
}
coder = null;
addresses = null;
if(info.length() <= 0){
info = "lat " + latitude + ", lon " + longitude;
}
else{
info += ("n" + "(lat " + latitude + ", lon " + longitude + ")");
}
RemoteViews views = new RemoteViews(getPackageName(), R.layout.gpswidget);
views.setTextViewText(R.id.txtInfo, info);
ComponentName thisWidget = new ComponentName(this, GPSWidgetProvider.class);
AppWidgetManager manager = AppWidgetManager.getInstance(this);
manager.updateAppWidget(thisWidget, views);
}
}
}
4.) Create and Write following into AppLog.java:
package com.example.gpsappwidgetexample;
import android.util.Log;
public class AppLog {
private static final String APP_TAG = "GPSWidget";
public static int logString(String message){
return Log.i(APP_TAG, message);
}
}
5.) Compile and build the project.
Note:- Application’s actual outcome can be tested on original device only.
Output
