Android battery level widget

Question

I'm working on android widget that displays the level of battery left.

It seem to work on the emulator except that the emulator's battery level doesn't move, so I can't test further. On real device (ICS), it only displays the initial textview("TEST") and doesn't do anything else.

Manifest

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.battery"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="17" />

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <receiver android:name="main.MyBatteryWidget"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
        </intent-filter>
        <meta-data android:name="android.appwidget.provider"
            android:resource="@xml/widget_info" />
    </receiver>
    <service android:name="main.MyBatteryWidget$BatteryUpdateService"
        android:exported="false" >
        <intent-filter>
            <action android:name="com.example.battery.action.UPDATE" />
        </intent-filter>
    </service>
</application>

widget_info.xml

<?xml version="1.0" encoding="utf-8"?>
<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
    android:updatePeriodMillis="0"
    android:minWidth="40dip"
    android:minHeight="72dip"
    android:initialLayout="@layout/widget_layout" >

</appwidget-provider>

widget_layout.xml

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

    <TextView android:id="@+id/textView"
        android:text="TEST"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />


</LinearLayout>

MyBatteryWidget.java

package main;

import android.app.Service;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.BatteryManager;
import android.os.IBinder;
import android.util.Log;
import android.widget.RemoteViews;

import com.example.battery.R;

public class MyBatteryWidget extends AppWidgetProvider {

    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager,
        int[] appWidgetIds) {
        Log.d("TEST", "onUpdate");
        context.getApplicationContext().startService(new Intent("com.example.battery.action.UPDATE"));
    }

    public static class BatteryUpdateService extends Service {
        private static int level = 0;
        private static int scale = 0;

        private BroadcastReceiver receiver = new BroadcastReceiver(){
            @Override
            public void onReceive(Context context, Intent intent) {
                String action = intent.getAction();

                if (action.equals(Intent.ACTION_BATTERY_CHANGED)) {
                    level = intent.getIntExtra(BatteryManager.EXTRA_LEVEL, -1);
                    scale = intent.getIntExtra(BatteryManager.EXTRA_SCALE, -1);
                    Log.d("TEST", "receive");
                    updateViews(context);
                }
            }
        };

        private void updateViews(Context context) {
            RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.widget_layout);
            views.setTextViewText(R.id.textView, String.valueOf(level / scale));
            ComponentName componentName = new ComponentName(context, MyBatteryWidget.class);
            AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);
            appWidgetManager.updateAppWidget(componentName, views);
        }

        @Override
        public int onStartCommand(Intent intent, int flags, int startId) {
            // TODO Auto-generated method stub
            Log.d("TEST", "start");
            registerReceiver(receiver, new IntentFilter(Intent.ACTION_BATTERY_CHANGED));
            return super.onStartCommand(intent, flags, startId);
        }

        @Override
        public IBinder onBind(Intent intent) {
            // TODO Auto-generated method stub
            return null;
        }

    }

}

Logcat

03-27 19:51:34.963: D/dalvikvm(608): Not late-enabling CheckJNI (already on)
03-27 19:51:35.043: E/Trace(608): error opening trace file: No such file or directory (2)
03-27 19:51:35.083: D/TEST(608): onUpdate
03-27 19:51:35.103: D/TEST(608): start
03-27 19:51:35.133: D/TEST(608): receive

You can change the battery level in the emulator using telnet: http://www.stealthcopter.com/blog/2010/07/changing-the-battery-percentage-in-an-avd-android-virtual-device-emulator/ — twaddington, Mar 28 '13 at 01:00

score 0 · Answer 1 · answered Mar 28 '13 at 01:15

0

Intent.ACTION_BATTERY_CHANGED

You have to listen it in Android Manifest

<receiver android:name=".myReceiver" >
    <intent-filter>
        <action android:name="Intent.ACTION_BATTERY_CHANGED" />
    </intent-filter>
</receiver>

answered Mar 28 '13 at 01:15

minhaz

4,233
3
33
49

You shouldn't need to register that there. According to official android tutorial, BatteryManager broadcasts them in a sticky intent. – awonderer Mar 28 '13 at 02:54
Sticky means after broadcast it stick around but if you want to receive regular broadcast then you have to register it in Manifest. – minhaz Mar 28 '13 at 03:09
I took `android.appwidget.action.APPWIDGET_UPDATE` out and tried above except I put `android:name="main.MyBatteryWidget"` for receiver. Do I need to modify something else in my code? It didn't do anything on emulator. – awonderer Mar 28 '13 at 03:20
As you are having trouble with this i recommend you try each module individually. And, FYI, i am not sure why you need service. – minhaz Mar 28 '13 at 03:29
I used service because of the tutorials and sample codes I saw around. Could you tell me what is wrong about using service here? – awonderer Mar 28 '13 at 05:34

score 0 · Accepted Answer · answered Mar 28 '13 at 20:02

0

For a working example have a look at my Mini Status Widget, see code

answered Mar 28 '13 at 20:02

j.holetzeck

4,048
2
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Android battery level widget

2 Answers2