I'm getting GoogleMap.clear on a null object reference

Question

I have a Google Maps based application and it was working with the methods getMap(), now with the new model getMapAsync, I'm having troubles when I want to clear or use in general the GoogleMap object,

java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.gms.maps.GoogleMap.clear()' on a null object reference.

I'm using a Fragment.

  @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        View view = inflater.inflate(R.layout.fragment_passenger_page1,
                container, false);
        MapFragment fm = (MapFragment) mainActivity.getFragmentManager().findFragmentById(R.id.map);
        fm.getMapAsync(this);
...
}

the problem is here when I use:

   @Override
    public void onResume() {

mMap.clear();

        if (listMarkers.size() > 0)

        {
            setMarker(listMarkers);
        }
        super.onResume();

    }

This function is called every time the App opens, and says that mMap is null.

Please help me.

Where is the `mMap` initialization goes ?? I do not see it in this code . — ADM, Dec 03 '18 at 04:10
Possible duplicate of [What is a NullPointerException, and how do I fix it?](https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) — ADM, Dec 03 '18 at 04:36
You got this problem because the map comes async, it means that your onResume will fired before that you will get initialized map object. Look at first answer, and work with map object after that getMapAsync will done. — Vadim Eksler, Dec 03 '18 at 06:34
I implemented the clear() function that runs after the map is ready, I need to do it this way because I don't want to create the map object every time the app opens, if the application is onPause I want to keep the map. — Sebastian Martinez, Dec 03 '18 at 13:04

score 1 · Answer 1 · answered Dec 03 '18 at 05:33

please implement OnMapReadyCallback interface and override

 @Override
 public void onMapReady(GoogleMap googleMap) {
    this.googleMap = googleMap;
    googleMap.clear()
    if (listMarkers.size() > 0)

    {
        setMarker(listMarkers);
    }


 }

and remove code from on resume methods

score 0 · Answer 2 · answered Dec 03 '18 at 12:58

thanks for your comments, I solved my problem by calling a clear() function in onResume, checking if the GoogleMap exists and if not creating it and passing to mMap.

 @Override
public void onResume() {

    clear();
    if (listMarkers.size() > 0)

    {
        setMarker(listMarkers);
    }
    super.onResume();

}

The clear function looks like:

public void clear() {

    GoogleMap gm = createMap();
    if (gm == null) {
        Log.e("clear", "The map is null"); //for testing purposes
        return;

    } else {
        Log.e("clear", "The map already exists"); //for testing purposes
        mMap = gm;
        mMap.clear();
    }


    startLocation = null;
    endLocation = null;
    txtFrom.setText("");
    txtTo.setText("");

}

And finally the createMap():

 private GoogleMap createMap() {

    if (mMap != null) {
        Log.e("create", "The map already exists"); // for testing purposes
        return mMap;
    }
    MapFragment fm = (MapFragment) 
    mainActivity.getFragmentManager().findFragmentById(R.id.map);
    try {
        fm.getMapAsync(this);
    } catch (Exception ex) {
        Log.e("Error", ex.getLocalizedMessage());
    }

    return null;

}

So in this way I always create a new GoogleMap if it doesn't exists.

If i'm doing something wrong don't hesitate to tell me :)

I'm getting GoogleMap.clear on a null object reference

2 Answers2