Button click event for android widget

Here is another answer with the following benefits:

• It handles all App Widget instances (a user might have multiple instances of your widget in various configurations/sizes on your screen). Coding for all instances is what the official documentation prescribes. See Guide > App Widgets > Using the AppWidgetProvider Class , scroll down to the code example for "ExampleAppWidgetProvider".
• The workhorse code in onReceive in effect calls onUpdate (so you reduce code duplication).
• The code in onUpdate(Context context) is generalised so that it can be dropped into any AppWidgetProvider subclass.

The code:

public class MyWidget extends AppWidgetProvider {

    private static final String ACTION_UPDATE_CLICK = 
              "com.example.myapp.action.UPDATE_CLICK";

    private static int mCount = 0;

    private static String getMessage() {
        return String.valueOf(mCount++);
    }

    private PendingIntent getPendingSelfIntent(Context context, String action) {
        // An explicit intent directed at the current class (the "self").
        Intent intent = new Intent(context, getClass());
        intent.setAction(action);
        return PendingIntent.getBroadcast(context, 0, intent, 0);
    }

    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager,
                         int[] appWidgetIds) {
        super.onUpdate(context, appWidgetManager, appWidgetIds);

        String message = getMessage();

        // Loop for every App Widget instance that belongs to this provider.
        // Noting, that is, a user might have multiple instances of the same
        // widget on
        // their home screen.
        for (int appWidgetID : appWidgetIds) {
            RemoteViews remoteViews = new RemoteViews(context.getPackageName(),
                                                      R.layout.my_widget);

            remoteViews.setTextViewText(R.id.textView_output, message);
            remoteViews.setOnClickPendingIntent(R.id.button_update,
                                                getPendingSelfIntent(context,
                                                           ACTION_UPDATE_CLICK)
            );

            appWidgetManager.updateAppWidget(appWidgetID, remoteViews);

        }
    }

    /**
     * A general technique for calling the onUpdate method,
     * requiring only the context parameter.
     *
     * @author John Bentley, based on Android-er code.
     * @see <a href="http://android-er.blogspot.com
     * .au/2010/10/update-widget-in-onreceive-method.html">
     * Android-er > 2010-10-19 > Update Widget in onReceive() method</a>
     */
    private void onUpdate(Context context) {
        AppWidgetManager appWidgetManager = AppWidgetManager.getInstance
                (context);

        // Uses getClass().getName() rather than MyWidget.class.getName() for
        // portability into any App Widget Provider Class
        ComponentName thisAppWidgetComponentName =
                new ComponentName(context.getPackageName(),getClass().getName()
        );
        int[] appWidgetIds = appWidgetManager.getAppWidgetIds(
                thisAppWidgetComponentName);
        onUpdate(context, appWidgetManager, appWidgetIds);
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        super.onReceive(context, intent);

        if (ACTION_UPDATE_CLICK.equals(intent.getAction())) {
            onUpdate(context);
        }
    }

}

The widget looks like this

This builds on the getPendingSelfIntent work of @Kels, @SharonHaimPour and @Erti-ChrisEelmaa.

It also builds on Android-er > 2010-10-19 > Update Widget in onReceive() method (not me) where it is demonstrated how to call onUpdate from onReceive, on an App Widget instance basis. I make that code general and wrap it in callOnUpdate.

Here is one example more that should help:

package com.automatic.widget;

import android.app.PendingIntent;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.widget.RemoteViews;

public class Widget extends AppWidgetProvider {

    private static final String SYNC_CLICKED    = "automaticWidgetSyncButtonClick";

    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        RemoteViews remoteViews;
        ComponentName watchWidget;

        remoteViews = new RemoteViews(context.getPackageName(), R.layout.widget_layout);
        watchWidget = new ComponentName(context, Widget.class);

        remoteViews.setOnClickPendingIntent(R.id.sync_button, getPendingSelfIntent(context, SYNC_CLICKED));
        appWidgetManager.updateAppWidget(watchWidget, remoteViews);
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO Auto-generated method stub
        super.onReceive(context, intent);

        if (SYNC_CLICKED.equals(intent.getAction())) {

            AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);

            RemoteViews remoteViews;
            ComponentName watchWidget;

            remoteViews = new RemoteViews(context.getPackageName(), R.layout.widget_layout);
            watchWidget = new ComponentName(context, Widget.class);

            remoteViews.setTextViewText(R.id.sync_button, "TESTING");

            appWidgetManager.updateAppWidget(watchWidget, remoteViews);

        }
    }

    protected PendingIntent getPendingSelfIntent(Context context, String action) {
        Intent intent = new Intent(context, getClass());
        intent.setAction(action);
        return PendingIntent.getBroadcast(context, 0, intent, 0);
    }
}

I found out how to do that.
Add an action to the AndroidManifest.xml file in the > <receiver><intent-filter> tag:

<action android:name="MY_PACKAGE_NAME.WIDGET_BUTTON" />

In the provider add a constant that matches the action name:

public static String WIDGET_BUTTON = "MY_PACKAGE_NAME.WIDGET_BUTTON";

In the onUpdate() method add a pending intent that matches the action:

Intent intent = new Intent(WIDGET_BUTTON);
PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
views.setOnClickPendingIntent(R.id.MY_BUTTON_ID, pendingIntent );

Finally, in the onRecieve() method, check the action name:

 if (WIDGET_BUTTON.equals(intent.getAction())) {
//your code here

    }