Notification and OnChangeLocation from GPSTracker Class

Question

I use a GPSTracker class, with the method OnLocationChanged I want to send a notification when ....the locaiton change :)

i use :

@Override
public void onLocationChanged(Location location) {
    latitude = (double) (location.getLatitude());
    longitude = (double) (location.getLongitude());
    //   Toast.makeText(this, "fffff", Toast.LENGTH_LONG).show();
    //  Toast.makeText(getApplicationContext(), Double.toString(latitude)   , Toast.LENGTH_LONG).show();

    Log.i("okok", "position changee" + Double.toString(latitude) + "-" + Double.toString(longitude));


        NotificationManager notif = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        Notification notify = new Notification(R.drawable.a, "tittle", System.currentTimeMillis());
        PendingIntent pending = PendingIntent.getActivity(getApplicationContext(), 0, new Intent(), 0);

        notify.setLatestEventInfo(getApplicationContext(), "subject", "body", pending);
        notif.notify(0, notify);

}

and there is an error on the 1st line of the NotificationLManager: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object android.content.Context.getSystemService(java.lang.String)' on a null object reference

Same issue when trying to use an HttpConnection to a remote website. I tryied already to use the try{} method

Would you have an idea pleaaaaase thanks David

GPSTracker? There is no such class in Android's SDK... Are you talking about extremely wrong written class from androidhive's so called tutorial? For your sanity, please, don't use it.. — Selvin, May 06 '16 at 06:51
The answers given so far are spot on and there's also [this useful discussion](http://stackoverflow.com/questions/7298731/when-to-call-activity-context-or-application-context) about the different ways to get a `Context` and which one to use in which use case. — Markus Kauppinen, May 06 '16 at 08:10

score 1 · Answer 1 · answered May 06 '16 at 06:23

1

I think your getting this error because your Context is null

you can try to wrap it like this and debug

if (getApplicationContext() != null) {
// Code goes here.
}

it has to do something with with your Context, try to access it different

it would have been better if you would have posted logcat

answered May 06 '16 at 06:23

Max

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public void onLocationChanged(Location location) { latitude = (double) (location.getLatitude()); longitude = (double) (location.getLongitude()); if (getApplicationContext() != null) { Toast.makeText(this, "fffff", Toast.LENGTH_LONG).show(); // Toast.makeText(getApplicationContext(), Double.toString(latitude) , Toast.LENGTH_LONG).show(); /* long now = location.getTime(); Log.i("gps", "onLocationChanged. gps time: " + now); notifBuilder.setContentText(now + "," + now ); getNotifMngr().notify(1, notifBuilder.getNotification());*/ } – david marchioni May 07 '16 at 11:13

score 1 · Answer 2 · answered May 06 '16 at 06:25

getSystemService(java.lang.String)

is a method of Context class. So it need a Context object to be called from. What is your GPSTracker class? Is it subclass Context class i.e. Activity, application, Service? If not call this method with a proper context object which can't be null at a time of calling it.

Your complete code for GPSTracker class help to spot the error in particular, otherwise you can identify it yourself.

Notification and OnChangeLocation from GPSTracker Class

2 Answers2