服务，计时器和通知…，但有错误.. :)

Question

I'm creating my first service. I have a service with a timer, when the timer run out, if a condition is verified, I want to send a notification. This is the code:

package app.tdgpisa.service;

import java.util.Timer;
import java.util.TimerTask;

import org.json.JSONArray;
import org.json.JSONException;

import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.support.v4.app.NotificationCompat;
import android.util.Log;
import app.tdgpisa.Bacheca;
import app.tdgpisa.R;
import app.tdgpisa.db.Database;

public class NotificaBacheca extends Service {
    private Timer miotimer = new Timer();
    private static  long intervallo = 10*1000;
    private long msg =0;
    Database database=new Database();
    private static final int SIMPLE_NOTIFICATION_ID = 1;
    NotificationManager mNotificationManager;

    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {

        Log.d("notifica", " inizio create");
        String messaggi = database.MessaggiNum();

        try {
            JSONArray jsonArray = new JSONArray(messaggi);
            for (int i = 0; i < jsonArray.length(); i++)
            {
                msg = jsonArray.getJSONObject(i).getInt("NUM");
                Log.d("notifica", "numero msg nel create: "+ msg);
            }

        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

    @Override
    public void onDestroy() {

    }

    @Override
    public void onStart(Intent intent, int startid) {
        StartServUpdateTask();
    }    

    private void StartServUpdateTask() {
        miotimer.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {
                Log.d("notifica", "parte il run");
                String messaggi = database.MessaggiNum();
                JSONArray jsonArray;
                try {
                    jsonArray = new JSONArray(messaggi);
                    long newmsg = jsonArray.getJSONObject(0).getLong("NUM");
                    Log.d("notifica", "numero msg nel run: "+ newmsg);
                    if (newmsg>msg){
                        msg=newmsg;
                        Log.d("notifica", "sono diversi, parte la notifica");
                        Notifica();
                    }
                } catch (JSONException e) {

                }

            }
        }, 0, intervallo);
    }
    private void Notifica() {

        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(NotificaBacheca.this);

        notificationBuilder.setContentTitle("TITOLO");
        notificationBuilder.setContentText("TESTO");
        notificationBuilder.setTicker("SCROLL TESTO");
        notificationBuilder.setWhen(System.currentTimeMillis());
        notificationBuilder.setSmallIcon(R.drawable.ic_launcher);
        notificationBuilder.setAutoCancel(true);

        Intent notificationIntent = new Intent(NotificaBacheca.this, Bacheca.class);
        PendingIntent contentIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0);
        notificationBuilder.setContentIntent(contentIntent);

        notificationBuilder.setDefaults(Notification.DEFAULT_SOUND | Notification.DEFAULT_LIGHTS | Notification.DEFAULT_VIBRATE);

        mNotificationManager.notify(SIMPLE_NOTIFICATION_ID, notificationBuilder.build());
    }


}

And this is the error:

11-19 13:51:56.752: E/AndroidRuntime(343): FATAL EXCEPTION: Timer-0
11-19 13:51:56.752: E/AndroidRuntime(343): java.lang.NullPointerException
11-19 13:51:56.752: E/AndroidRuntime(343):  at app.tdgpisa.service.NotificaBacheca.Notifica(NotificaBacheca.java:104)
11-19 13:51:56.752: E/AndroidRuntime(343):  at app.tdgpisa.service.NotificaBacheca.access$2(NotificaBacheca.java:87)
11-19 13:51:56.752: E/AndroidRuntime(343):  at app.tdgpisa.service.NotificaBacheca$1.run(NotificaBacheca.java:78)
11-19 13:51:56.752: E/AndroidRuntime(343):  at java.util.Timer$TimerImpl.run(Timer.java:284)

Can anyone help me? Sorry for, eventualy, big mistake... :) Thank you!

Answer 1

mNotificationManager is null. It was never intialized to anything. The null pointer line number should have told you everything you needed.

Answer 2

Your mNotificationManager is never set, but you call mNotificationManager.notify(SIMPLE_NOTIFICATION_ID, notificationBuilder.build()); on line 104.

You should set mNotificationManager before.