Null Pointer Exception while creating map example

Question

It keeps on getting this error for me and on the emulator it is showing force close. Not getting where it went wrong. Actually I am creating a program (with reference to a book) to get the location data. Following is my program and logcat error. I referred these link1, link2, but I couldn't find the solution from those. Can someone please suggest me what is the problem? Even I already added this in manifest

<uses-permission android:name="android.permission.INTERNET"/>
     <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

and in the application tag

<uses-library android:name="com.google.android.maps"/>

and here is my .java file

public class LBSMap extends MapActivity {

    MapView mapView;
    MapController mc;
    GeoPoint p;

    LocationManager lm;
    LocationListener locationListener;

    private class MapOverlay extends com.google.android.maps.Overlay
    {
        public boolean draw(Canvas canvas, MapView mapView, boolean shadow, long when)
        {
            super.draw(canvas, mapView, shadow);
            Point screenPts=new Point();
            mapView.getProjection().toPixels(p, screenPts);

            Bitmap bmp=BitmapFactory.decodeResource(getResources(), R.drawable.pushpin);
            canvas.drawBitmap(bmp, screenPts.x, screenPts.y-50,null);
            return true;
        }

        public boolean onTouchEvent(MotionEvent event,MapView mapView)
        {
            if(event.getAction()==1)
            {
                GeoPoint p=mapView.getProjection().fromPixels((int)event.getX(),(int)event.getY());

            Geocoder geoCoder=new Geocoder(getBaseContext(),Locale.getDefault());
            try{
                List<Address> addresses=geoCoder.getFromLocation(p.getLatitudeE6()/1E6, p.getLongitudeE6()/1E6, 1);
                String add="";
                if(addresses.size()>0)
                {
                    for(int i=0;i<addresses.get(0).getMaxAddressLineIndex();i++)
                        add +=addresses.get(0).getAddressLine(i) + "\n";
                }
                Toast.makeText(getBaseContext(),add,Toast.LENGTH_SHORT).show();

            }catch(IOException e){
                e.printStackTrace();
            }
            return true;
            }
            return false;
        }
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_lbsmap);

        mapView=(MapView)findViewById(R.id.mapView);
        mapView.setBuiltInZoomControls(true);
        mapView.setSatellite(true);
        mapView.setTraffic(true);

        mc=mapView.getController();

        Geocoder geoCoder=new Geocoder(this,Locale.getDefault());

        try{
            List<Address> addresses=geoCoder.getFromLocation(p.getLatitudeE6()/1E6, p.getLongitudeE6()/1E6, 1); //line 103
            String add="";
            if(addresses.size()>0)
            {
                for(int i=0;i<addresses.get(0).getMaxAddressLineIndex();i++)
                    add +=addresses.get(0).getAddressLine(i) + "\n";
            }
            Toast.makeText(getBaseContext(),add,Toast.LENGTH_SHORT).show();

        }catch(IOException e){
            e.printStackTrace();
        }

        MapOverlay mapOverlay=new MapOverlay();
        List<Overlay> listOfOverlays=mapView.getOverlays();
        listOfOverlays.clear();
        listOfOverlays.add(mapOverlay);

        mapView.invalidate();

        lm=(LocationManager)getSystemService(Context.LOCATION_SERVICE);
        locationListener = new MyLocationListener();
    }

    public void onResume()
    {
        super.onResume();
        lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
    }

    public void onPause()
    {
        super.onPause();
        lm.removeUpdates(locationListener);
    }

    private class MyLocationListener implements LocationListener
    {
        public void onLocationChanged(Location loc)
        {
            if(loc!=null){
                Toast.makeText(getBaseContext(), "Location changed : Lat: "+loc.getLatitude()+ "Lng: "+loc.getLongitude(), Toast.LENGTH_SHORT).show();
                p=new GeoPoint((int)(loc.getLatitude()*1E6),(int)(loc.getLongitude()*1E6));
                mc.animateTo(p);
                mc.setZoom(18);
            }

        }
        public void onProviderDisabled(String provider)
        {}
        public void onProviderEnabled(String provider)
        {}
        public void onStatusChanged(String provider, int status, Bundle extras)
        {}
    }


    @Override
    public boolean isRouteDisplayed()
    {
        return false;
    }
}

Below is the screenshot of the logcat.

enter image description here

@RaghavSood and umar I edited my question with line no 103. Please check. — Spike, Sep 21 '12 at 17:27

score 0 · Answer 1 · answered Sep 21 '12 at 17:31

0

I'm guessing the GeoPoint p is null in your onCreate(), as when you assign a value to it in the Overlay code, you use

GeoPoint p=mapView.getProjection().fromPixels((int)event.getX(),(int)event.getY());

Which creates another local variable, instead of using the global one. Try using:

p=mapView.getProjection().fromPixels((int)event.getX(),(int)event.getY());

You may need to add a final modifier to the declaration to have it work inside another class.

answered Sep 21 '12 at 17:31

Raghav Sood

81,899
22
187
195

Thanks for your response. Tried this. Still showing the same error.:( – Spike Sep 21 '12 at 17:47
when I added sop before the line p=mapView.getProjection().fromPixels((int)event.getX(),(int)event.getY()); It gives the value of p object as null. But why? – Spike Sep 21 '12 at 18:12
I'm guessing that since you assign p in onTouchEvent, it'll be null until you touch the map. – Raghav Sood Sep 21 '12 at 18:17
Yes. I too thought the same thing. But in the book it is given like that. When I initialize p to some values in the onCreate() method, it is working. BTW How come there is only one android chat room now and I am unable to enter that room. – Spike Sep 21 '12 at 18:25
Glad it's working. There are still a few Android rooms. You may not have access to the ones with diamonds next to them, and hence may not be able to talk. – Raghav Sood Sep 21 '12 at 18:34
let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/16976/discussion-between-anoop-kumar-and-raghav-sood) – Spike Sep 21 '12 at 18:45

score 0 · Answer 2 · edited Sep 21 '12 at 23:20

0

Please check that you have internet access code for SDK version > 9

// Allow network access

    if (android.os.Build.VERSION.SDK_INT > 9) {

        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
        StrictMode.setThreadPolicy(policy);

    }

edited Sep 21 '12 at 23:20

Renan

462
7
24

answered Sep 21 '12 at 17:37

Srimanta Panda

1
1

Null Pointer Exception while creating map example

2 Answers2