some issue in detecting location application crashes

Question

I am Trying to develop small application in which i am trying to Detect Location.

I am using the following code but i don't know why my application crashes. It show the application stops Unfortunately.

Here is the code. Please tell me if there is any bug and if not then please at least reply.

Thanks.

Here is the Code.

package com.project.kamani.nearby;

import java.io.IOException;
import java.util.List;
import java.util.Locale;

import android.app.Activity;
import android.location.Address;
import android.location.Criteria;
import android.location.Geocoder;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.widget.Toast;

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapFragment;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

public class Map extends Activity implements LocationListener{

public GoogleMap google_map;

public List<Address> addresses;

public Geocoder geocoder;

private Location location;

private double lat;
private double lang;

private Criteria criteria;

private LocationManager location_manager;

private String provider;

private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES=20;//DISTANCE IN METERS
private static final long MIN_TIME_BW_UPDATES=1000*60*1;// TAKES UPDATE AFTER 1 MINUTES

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    if(isGooglePlayAvailable())
    {

        criteria=new Criteria();

        setContentView(R.layout.mapdemo);

        getGoogleMap();

        getUserLocation();

        //Toast.makeText(this, "Latitude:"+lat+" Longitude:"+lang, Toast.LENGTH_LONG).show();

        getAddress(lat,lang);

        drawMarker(lat,lang);

    }

}

private boolean isGooglePlayAvailable(){

    int status=GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);

    if(status==ConnectionResult.SUCCESS)
        return true;
    else
        GooglePlayServicesUtil.getErrorDialog(status, this, 10).show();
    return false;

}

private void getGoogleMap(){

    if(google_map==null){

        google_map=((MapFragment)getFragmentManager().findFragmentById(R.id.map)).getMap();

    }

}

private void drawMarker(double lattitude,double longitude){
    google_map.clear();

    google_map.setMyLocationEnabled(true);

    LatLng latlng=new LatLng(lattitude, longitude);

    google_map.moveCamera(CameraUpdateFactory.newLatLng(latlng));
    google_map.animateCamera(CameraUpdateFactory.zoomTo(15));

    LatLng currentPosition = new LatLng(lattitude,longitude);
    google_map.addMarker(new MarkerOptions().position(currentPosition).snippet("Address:" + addresses.get(0).getAddressLine(0) + "City:"+ addresses.get(0).getAddressLine(1)+"Country:"+addresses.get(0).getAddressLine(2)).icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED)).title("ME"));
}

private void getAddress(double lattitude,double longitude){

    geocoder=new Geocoder(Map.this, Locale.getDefault());

    try {
        addresses=geocoder.getFromLocation(lattitude, longitude, 1);
        Toast.makeText(Map.this, "Address:" + addresses.get(0).getAddressLine(0) + "City:"+ addresses.get(0).getAddressLine(1)+"Country:"+addresses.get(0).getAddressLine(2), Toast.LENGTH_LONG).show();
    } catch (IOException e) {
        e.printStackTrace();
    }

}

private void getUserLocation(){

    location_manager=(LocationManager) getSystemService(LOCATION_SERVICE);
    if(location_manager!=null){
        provider=location_manager.getBestProvider(criteria, true);
        location=location_manager.getLastKnownLocation(provider);
        location_manager.requestLocationUpdates(provider, Map.MIN_TIME_BW_UPDATES, Map.MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
        lat=location.getLatitude();
        lang=location.getLongitude();
    }
}

@Override
public void onLocationChanged(Location location) {

    google_map.clear();

    drawMarker(lat, lang);

}

@Override
public void onProviderDisabled(String provider) {
    // TODO Auto-generated method stub

}

@Override
public void onProviderEnabled(String provider) {
    // TODO Auto-generated method stub

}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
    // TODO Auto-generated method stub

}

}

Here is the snapshot that error i am getting in logcat. enter image description here

I hope it will be helpful to solve error.

EDIT:-

If you don't want to monitor once again full code just try to view at getUserLocation method still the application stops working when i enable the GPS thanks for your support.

Are you running this code in device or emulator.Because "Geocoder" class will not work in emulator so you must check in real device. — Biraj Zalavadia, Sep 11 '13 at 04:08
can you please copy an paste the actual stacktrace. The picture is hard to see. — Emmanuel, Sep 11 '13 at 12:06
@njzk2 when i am trying to copy the error from logcat it disappers. i am updating the above code please check it out and thanks for helping. — Nirav Kamani, Sep 11 '13 at 14:26
@njzk2 right now i can't say because i modified some code and as we know maps are unable to run inside emulator and i am not having any device right now to check out thanks once again for support. can you tell me what is the problem now over here?And if still it throws NullPointerException for location then what can i do? — Nirav Kamani, Sep 11 '13 at 14:36

score 2 · Accepted Answer · answered Sep 11 '13 at 04:11

2

location is never initialized. Your are setting location as the variable that will hold the return value of getUserLocation() and it is also its parameter; both are null.

answered Sep 11 '13 at 04:11

Emmanuel

13,083
4
39
53

Hi brother i want to tell you after making correction that you told me i done that now when i enabling GPS in my Device then only application crashes can you tell me why it happens?If the GPS is off then app works fine. – Nirav Kamani Sep 11 '13 at 11:01
the parameter is not used, it is unlikely to cause the NPE – njzk2 Sep 11 '13 at 11:41
he is passing the location which is null, and return the same thing he passed in to the method. Then location is used to get the latitude; hence it is null and it crashes. – Emmanuel Sep 11 '13 at 12:04

score 0 · Answer 2 · answered Nov 09 '13 at 10:49

public class MainActivity extends MapActivity implements LocationListener {

private MapView mapView;

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

    // Getting reference to MapView
    mapView = (MapView) findViewById(R.id.map_view);

    // Setting Zoom Controls on MapView
    mapView.setBuiltInZoomControls(true);

    // Getting LocationManager object from System Service LOCATION_SERVICE
    LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);

    // Creating a criteria object to retrieve provider
    Criteria criteria = new Criteria();

    // Getting the name of the best provider
    String provider = locationManager.getBestProvider(criteria, true);

    // Getting Current Location
    Location location = locationManager.getLastKnownLocation(provider);

    if(location!=null){
        onLocationChanged(location);
    }

    locationManager.requestLocationUpdates(provider, 20000, 0, this);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}

@Override
protected boolean isRouteDisplayed() {
    // TODO Auto-generated method stub
    return false;
}

@Override
public void onLocationChanged(Location location) {
    TextView tvLocation = (TextView) findViewById(R.id.tv_location);

    // Getting latitude
    double latitude = location.getLatitude();

    // Getting longitude
    double longitude = location.getLongitude();

    // Setting latitude and longitude in the TextView tv_location
    tvLocation.setText("Latitude:" +  latitude  + ", Longitude:"+ longitude );

    // Creating an instance of GeoPoint corresponding to latitude and longitude
    GeoPoint point = new GeoPoint((int)(latitude * 1E6), (int)(longitude*1E6));

    // Getting MapController
    MapController mapController = mapView.getController();

    // Locating the Geographical point in the Map
    mapController.animateTo(point);

    // Applying a zoom
    mapController.setZoom(15);

    // Redraw the map
    mapView.invalidate();

    // Getting list of overlays available in the map
    List<Overlay> mapOverlays = mapView.getOverlays();

    // Creating a drawable object to represent the image of mark in the map
    Drawable drawable = this.getResources().getDrawable(R.drawable.cur_position);

    // Creating an instance of ItemizedOverlay to mark the current location in the map
    CurrentLocationOverlay currentLocationOverlay = new CurrentLocationOverlay(drawable);

    // Creating an item to represent a mark in the overlay
    OverlayItem currentLocation = new OverlayItem(point, "Current Location", "Latitude : " + latitude + ", Longitude:" + longitude);

    // Adding the mark to the overlay
    currentLocationOverlay.addOverlay(currentLocation);

    // Clear Existing overlays in the map
    mapOverlays.clear();

    // Adding new overlay to map overlay
    mapOverlays.add(currentLocationOverlay);

}

@Override
public void onProviderDisabled(String provider) {
    // TODO Auto-generated method stub
}

@Override
public void onProviderEnabled(String provider) {
    // TODO Auto-generated method stub
}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
    // TODO Auto-generated method stub
}
}

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some issue in detecting location application crashes

2 Answers2