hyeri hyeri - 1 month ago 9
Android Question

Latitude and Longitude are null

I'm working on an app getting user's current location and showing it on map, as well as Latitude and Longitude on the screen, so far everything is going fine, the map's showing my current location as well as displaying latitude and longitude on the screen using this code

@Override
public void onLocationChanged(Location location) {

TextView tvLocation = (TextView) findViewById(R.id.tv_location);

// Getting latitude of the current location
double latitude = location.getLatitude();

// Getting longitude of the current location
double longitude = location.getLongitude();

// Creating a LatLng object for the current location
LatLng latLng = new LatLng(latitude, longitude);

// Showing the current location in Google Map
googleMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));

// Zoom in the Google Map
googleMap.animateCamera(CameraUpdateFactory.zoomTo(15));

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

}


Problem occurs when I want to send this latitude and longitude on server , it throws NUll pointer exception

01-04 23:27:38.759 29286-29286/io.xgear.geotag E/AndroidRuntime: FATAL
EXCEPTION: main
Process: io.xgear.geotag, PID: 29286
java.lang.NullPointerException
at io.xgear.geotag.MainActivity$GeoTagTask.<init>(MainActivity.java:234)
at io.xgear.geotag.MainActivity$1.onClick(MainActivity.java:181)
at android.view.View.performClick(View.java:4633)
at android.view.View$PerformClick.run(View.java:19270)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:146)
at android.app.ActivityThread.main(ActivityThread.java:5602)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
at dalvik.system.NativeStart.main(Native Method)


this is the piece of code for getting latitude and longitude to send

public class GeoTagTask extends AsyncTask<Void, Void, Boolean> {
private final String shopCode;
Location location;
private String lat = Double.toString(location.getLatitude());
private String lng = Double.toString(location.getLongitude());


private boolean isConnect;
GeoTagTask(String shopId) {
shopCode = shopId;
isConnect = false;

}

@Override
protected Boolean doInBackground(Void... params) {
boolean res = false;
try {
ContentValues nameValuePairs = new ContentValues();
nameValuePairs.put("Id", shopCode);
nameValuePairs.put("lat", lat);
nameValuePairs.put("lng", lng);
//Toast.makeText(getApplicationContext(), "Your Location is - \nLat: " + lat + "\nLong: " + lng, Toast.LENGTH_LONG).show();
Log.i("Latitude", lat+"");

Post post = new Post(getApplicationContext());
String result = "";
// isConnect = post.isConnected();
// if(isConnect) {
result = post.doPost(nameValuePairs);
jsonObj = new JSONObject(result);
Log.i("Result", result+"");
if(jsonObj.getInt("success") == 1)
res = true;
// }

} catch (JSONException e) {
e.printStackTrace();
}
return res;
}


and this is the full code

package io.xgear.geotag;


import android.Manifest;
import android.app.Dialog;
import android.app.FragmentTransaction;
import android.content.pm.PackageManager;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.FragmentActivity;
import android.view.Menu;
import android.widget.TextView;
import android.support.v4.app.Fragment;

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.GoogleMapOptions;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.annotation.TargetApi;
import android.content.ContentValues;
import android.os.AsyncTask;
import android.os.Build;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.InputType;
import android.text.TextUtils;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import org.json.JSONException;
import org.json.JSONObject;



import io.xgear.geotag.helper.Post;

public class MainActivity extends FragmentActivity implements LocationListener {
GoogleMap googleMap;
private GeoTagTask mAuthTask = null;
GPSTracker gps;
private JSONObject jsonObj;

// UI references.
private EditText txtShopCode;
private EditText lblAddress;
private View mProgressView;
private View mGeoTagForm;
private Button btnGeoTag;

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

txtShopCode = (EditText) findViewById(R.id.txtShopCode);
btnGeoTag = (Button) findViewById(R.id.btnGeoTag);
mGeoTagForm = (View) findViewById(R.id.geoTagForm);
mProgressView = findViewById(R.id.geoTagProgress);

// Getting Google Play availability status
int status = GooglePlayServicesUtil.isGooglePlayServicesAvailable(getBaseContext());

// Showing status
if (status != ConnectionResult.SUCCESS) { // Google Play Services are not available

int requestCode = 10;
Dialog dialog = GooglePlayServicesUtil.getErrorDialog(status, this, requestCode);
dialog.show();

} else { // Google Play Services are available

// Getting reference to the SupportMapFragment of activity_main.xml
SupportMapFragment fm = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);

// Getting GoogleMap object from the fragment
googleMap = fm.getMap();

// Enabling MyLocation Layer of Google Map
googleMap.setMyLocationEnabled(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
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return;
}
Location location = locationManager.getLastKnownLocation(provider);

if(location!=null){
onLocationChanged(location);
}
locationManager.requestLocationUpdates(provider, 20000, 0, this);
}

btnGeoTag.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
String shopid = txtShopCode.getText().toString();
boolean cancel = false;
View focusView = null;

//txtShopCode.setInputType(InputType.TYPE_CLASS_NUMBER);

if (TextUtils.isEmpty(shopid)) {
txtShopCode.setError(getString(R.string.error_field_required));
focusView = txtShopCode;
cancel = true;

}
else {


showProgress(true);
mAuthTask = new GeoTagTask(shopid);
mAuthTask.execute((Void) null);
}
}

});

}

//


// public void btnGeoTag_Click(View v){
//
// }
@TargetApi(Build.VERSION_CODES.HONEYCOMB_MR2)
public void showProgress(final boolean show) {
// On Honeycomb MR2 we have the ViewPropertyAnimator APIs, which allow
// for very easy animations. If available, use these APIs to fade-in
// the progress spinner.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2) {
int shortAnimTime = getResources().getInteger(android.R.integer.config_shortAnimTime);

mGeoTagForm.setVisibility(show ? View.GONE : View.VISIBLE);
mGeoTagForm.animate().setDuration(shortAnimTime).alpha(
show ? 0 : 1).setListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
mGeoTagForm.setVisibility(show ? View.GONE : View.VISIBLE);
}
});

mProgressView.setVisibility(show ? View.VISIBLE : View.GONE);
mProgressView.animate().setDuration(shortAnimTime).alpha(
show ? 1 : 0).setListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
mProgressView.setVisibility(show ? View.VISIBLE : View.GONE);
}
});
} else {
// The ViewPropertyAnimator APIs are not available, so simply show
// and hide the relevant UI components.
mProgressView.setVisibility(show ? View.VISIBLE : View.GONE);
mGeoTagForm.setVisibility(show ? View.GONE : View.VISIBLE);
}
}

public class GeoTagTask extends AsyncTask<Void, Void, Boolean> {
private final String shopCode;
Location location;
private String lat = Double.toString(location.getLatitude());
private String lng = Double.toString(location.getLongitude());


private boolean isConnect;
GeoTagTask(String shopId) {
shopCode = shopId;
isConnect = false;

}

@Override
protected Boolean doInBackground(Void... params) {
boolean res = false;
try {
ContentValues nameValuePairs = new ContentValues();
nameValuePairs.put("Id", shopCode);
nameValuePairs.put("lat", lat);
nameValuePairs.put("lng", lng);
//Toast.makeText(getApplicationContext(), "Your Location is - \nLat: " + lat + "\nLong: " + lng, Toast.LENGTH_LONG).show();
Log.i("Latitude", lat+"");

Post post = new Post(getApplicationContext());
String result = "";
// isConnect = post.isConnected();
// if(isConnect) {
result = post.doPost(nameValuePairs);
jsonObj = new JSONObject(result);
Log.i("Result", result+"");
if(jsonObj.getInt("success") == 1)
res = true;
// }

} catch (JSONException e) {
e.printStackTrace();
}
return res;
}

@Override
protected void onPostExecute(final Boolean success) {
mAuthTask = null;
showProgress(false);

if (success) {
// Intent intent = new Intent(LoginActivity.this, MainActivity.class);
// intent.putExtra("jsonObj", jsonObj.toString());
// startActivity(intent);
txtShopCode.getText().clear();
txtShopCode.requestFocus();
Toast.makeText(getBaseContext(), "Your shop is geo tagged ", Toast.LENGTH_LONG).show();

} else {
// if(isConnect){
// mPasswordView.setError(getString(R.string.error_incorrect_password));
// mPasswordView.requestFocus();

// }
// else
Toast.makeText(getBaseContext(), R.string.geoTagError, Toast.LENGTH_LONG).show();
}
}

@Override
protected void onCancelled() {
mAuthTask = null;
showProgress(false);
}
}


@Override
public void onLocationChanged(Location location) {

TextView tvLocation = (TextView) findViewById(R.id.tv_location);

// Getting latitude of the current location
double latitude = location.getLatitude();

// Getting longitude of the current location
double longitude = location.getLongitude();

// Creating a LatLng object for the current location
LatLng latLng = new LatLng(latitude, longitude);

// Showing the current location in Google Map
googleMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));

// Zoom in the Google Map
googleMap.animateCamera(CameraUpdateFactory.zoomTo(15));

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

}

@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
}

// @Override
// public boolean onCreateOptionsMenu(Menu menu) {
// // Inflate the menu; this adds items to the action bar if it is present.
// getMenuInflater().inflate(R.menu.activity_main, menu);
// return true;
// }
}


UPDATE
I have added thes lines in GeoTagTask the button is working the app is not crashing but I'm not sure if it's going to work if location is changed because

if( location != null){
onLocationChanged(location);
}
locationManager.requestLocationUpdates(provider, 20000, 0, this);


is giving me errors .

The lines I have added

LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
Criteria criteria = new Criteria();
String provider = locationManager.getBestProvider(criteria, true);

Location location = locationManager.getLastKnownLocation(provider);

Answer

Problem

Problem is inside GeoTagTask ,

Location location;
private String lat = Double.toString(location.getLatitude());
private String lng = Double.toString(location.getLongitude());

You are accessing an uninitialized variable.

Solution

Make onCreate location a global variable,

public class MainActivity extends FragmentActivity implements LocationListener {
    Location location;
    void onCreate() {
        ....
        location = locationManager.getLastKnownLocation(provider);
        ....
    }
}

Use the global variable inside GeoTagTask,

public class GeoTagTask extends AsyncTask<Void, Void, Boolean> {
        private String lat = Double.toString(location.getLatitude());
        private String lng = Double.toString(location.getLongitude());
        ...
}
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