NullPointerException en AlarmManager.setRepeating()-ElapsedRealTime-Android

sdk background-service

Question

Estoy desarrollando una aplicación para Android, que enciende / apaga el wifi después de cada 5 segundos (5 segundos son solo para probar) Si esta información ayuda: Estoy usando un NavigationDrawer para esta aplicación. Estoy usando la alarma elapsedRealTime para esto. El usuario selecciona la hora de un menú desplegable y después del tiempo seleccionado, la aplicación activa / desactiva wifi. Por ejemplo: cuando él (el usuario) selecciona 30 minutos desde el menú desplegable (spinner), el wifi se debe encender / apagar después de 30 minutos. Creo que tengo todo implementado (como BroadcastReceiver , IntentService ).

Mi código si ayuda. Así es como llamo a mi clase SpinnerTimeOnItemSelectedListener .

public class TweaksFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
view = inflater.inflate(R.layout.fragment_tweaks, container, false);
addListenerOnSpinnerItemSelection();
return view;
}
public void addListenerOnSpinnerItemSelection(){
spinnerSelectTime = (Spinner) view.findViewById(R.id.spinner_select_time);
spinnerSelectTime.setOnItemSelectedListener(new SpinnerTimeOnItemSelectedListener());
}

En SpinnerTimeOnItemSelectedListener estoy creando la alarma y ejecutando BroadCastReceiver después de la alarma

 public class SpinnerTimeOnItemSelectedListener extends Activity implements AdapterView.OnItemSelectedListener {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
if(parent.getItemAtPosition(position).toString().equals("Zeit auswählen") || parent.getItemAtPosition(position).toString().equals("Select Time")){
//onNothingSelected(parent);
Toast.LENGTH_SHORT).show();
} else if (parent.getItemAtPosition(position).toString().equals("30min")){
alarm(parent);
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
public void alarm(AdapterView<?> parent) {
try {
Toast.makeText(parent.getContext(), "alarm() is called", Toast.LENGTH_SHORT).show();
Intent intent = new Intent(this, BroadCastReceiver.class);
PendingIntent mAlarmSender = PendingIntent.getBroadcast(this, 0, intent, 0);
long firstTime = SystemClock.elapsedRealtime();
AlarmManager am = (AlarmManager) getSystemService(ALARM_SERVICE);
am.setRepeating(AlarmManager.ELAPSED_REALTIME,
firstTime, 10, mAlarmSender);
} catch (Exception e) {
e.printStackTrace();
}
}
}

Mi clase BroadCastReceiver

public class BroadCastReceiver extends WakefulBroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
Toast.makeText(context, "BroadCastReceiver is running", Toast.LENGTH_SHORT).show();
startWakefulService(context,new Intent(context, BackgroundService.class));
}

}

Mi clase BackgroundService

public class BackgroundService extends IntentService {
public BackgroundService() {
super("BackgroundService");
}
private WifiManager wifiManager;
@Override
protected void onHandleIntent(Intent intent) {
// Hier kommt der Code zum ein und ausschalten (von z.B. wifi)
// Ein Intentservice gibt nichts auf der UI aus
wifiManager = (WifiManager) this.getSystemService(Context.WIFI_SERVICE);
if (wifiManager.isWifiEnabled()) {
wifiManager.setWifiEnabled(false);
} else {
wifiManager.setWifiEnabled(true);
}
}
}

Mi archivo Manifest

 <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.selfmade.ali.wifionoffer" >
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".MyActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".SpinnerTimeOnItemSelectedListener" ></activity>
<activity android:name=".ElapsedRealtimeAlarm"></activity>
<receiver android:name=".BroadCastReceiver" ></receiver>
<service android:name=".BackgroundService" android:exported="false" android:enabled="true" ></service>
</application>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />

Me estoy convirtiendo en una NullPointerException en esta línea: am.setRepeating(AlarmManager.ELAPSED_REALTIME, firstTime, 10000, mAlarmSender); ¿Cuál puede ser el problema y cómo puedo solucionarlo? Aquí está el logcat si ayuda:

07-27 15:24:29.490 20446-20446/com.selfmade.ali.wifionoffer W/System.err﹕ java.lang.NullPointerException
07-27 15:24:29.500 20446-20446/com.selfmade.ali.wifionoffer W/System.err﹕ at com.selfmade.ali.wifionoffer.SpinnerTimeOnItemSelectedListener.alarm(SpinnerTimeOnItemSelectedListener.java:93)
07-27 15:24:29.500 20446-20446/com.selfmade.ali.wifionoffer W/System.err﹕ at com.selfmade.ali.wifionoffer.SpinnerTimeOnItemSelectedListener.onItemSelected(SpinnerTimeOnItemSelectedListener.java:38)
07-27 15:24:29.500 20446-20446/com.selfmade.ali.wifionoffer W/System.err﹕ at android.widget.AdapterView.fireOnSelected(AdapterView.java:956)
07-27 15:24:29.500 20446-20446/com.selfmade.ali.wifionoffer W/System.err﹕ at android.widget.AdapterView.access$200(AdapterView.java:49)
07-27 15:24:29.500 20446-20446/com.selfmade.ali.wifionoffer W/System.err﹕ at android.widget.AdapterView$SelectionNotifier.run(AdapterView.java:920)
07-27 15:24:29.500 20446-20446/com.selfmade.ali.wifionoffer W/System.err﹕ at android.os.Handler.handleCallback(Handler.java:733)
07-27 15:24:29.500 20446-20446/com.selfmade.ali.wifionoffer W/System.err﹕ at android.os.Handler.dispatchMessage(Handler.java:95)
07-27 15:24:29.500 20446-20446/com.selfmade.ali.wifionoffer W/System.err﹕ at android.os.Looper.loop(Looper.java:157)
07-27 15:24:29.500 20446-20446/com.selfmade.ali.wifionoffer W/System.err﹕ at android.app.ActivityThread.main(ActivityThread.java:5356)
07-27 15:24:29.500 20446-20446/com.selfmade.ali.wifionoffer W/System.err﹕ at java.lang.reflect.Method.invokeNative(Native Method)
07-27 15:24:29.500 20446-20446/com.selfmade.ali.wifionoffer W/System.err﹕ at java.lang.reflect.Method.invoke(Method.java:515)
07-27 15:24:29.500 20446-20446/com.selfmade.ali.wifionoffer W/System.err﹕ at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
07-27 15:24:29.500 20446-20446/com.selfmade.ali.wifionoffer W/System.err﹕ at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
07-27 15:24:29.500 20446-20446/com.selfmade.ali.wifionoffer W/System.err﹕ at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:132)
07-27 15:24:29.500 20446-20446/com.selfmade.ali.wifionoffer W/System.err﹕ at dalvik.system.NativeStart.main(Native Method)
07-27 15:24:51.692 20446-20446/com.selfmade.ali.wifionoffer W/IInputConnectionWrapper﹕ getExtractedText on inactive InputConnection
07-27 15:24:51.692 20446-20446/com.selfmade.ali.wifionoffer W/IInputConnectionWrapper﹕ getTextBeforeCursor on inactive InputConnection
07-27 15:24:51.702 20446-20446/com.selfmade.ali.wifionoffer W/IInputConnectionWrapper﹕ getSelectedText on inactive InputConnection
07-27 15:24:51.702 20446-20446/com.selfmade.ali.wifionoffer W/IInputConnectionWrapper﹕ getTextAfterCursor on inactive InputConnection

Estoy teniendo este problema durante 3 días y espero que alguien me pueda ayudar