Develop Reference

Draggable marker for android studio

I need to use google map in android app to get the address from the users. The customer can drag the marker to anywhere in the map and need to select continue.
But my code is working like already there a marker and if you long pressed then a new marker will come and you can drag and drop anywhere, but I need to remove the first marker.
package com.restaurant.grillizadmin;
import androidx.annotation.NonNull;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import androidx.fragment.app.FragmentActivity;
import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.location.Address;
import android.location.Geocoder;
import android.location.Location;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import com.google.android.gms.location.FusedLocationProviderClient;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
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.Marker;
import com.google.android.gms.maps.model.MarkerOptions;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.firestore.DocumentReference;
import com.google.firebase.firestore.FirebaseFirestore;
import com.restaurant.grillizadmin.Domain.Items;
import java.io.IOException;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback, GoogleMap.OnMapLongClickListener, GoogleMap.OnMarkerDragListener {
private static final String TAG = "MapsActivity";
private GoogleMap mMap;
private Geocoder geocoder;
private int ACCESS_LOCATION_REQUEST_CODE = 10001;
FusedLocationProviderClient fusedLocationProviderClient;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
geocoder = new Geocoder(this);
fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this);
}
/**
* Manipulates the map once available.
* This callback is triggered when the map is ready to be used.
* This is where we can add markers or lines, add listeners or move the camera. In this case,
* we just add a marker near Sydney, Australia.
* If Google Play services is not installed on the device, the user will be prompted to install
* it inside the SupportMapFragment. This method will only be triggered once the user has
* installed Google Play services and returned to the app.
*/
#Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
mMap.setOnMapLongClickListener(this);
mMap.setOnMarkerDragListener(this);
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
enableUserLocation();
zoomToUserLocation();
} else {
if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.ACCESS_FINE_LOCATION)) {
//We can show user a dialog why this permission is necessary
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, ACCESS_LOCATION_REQUEST_CODE);
} else {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, ACCESS_LOCATION_REQUEST_CODE);
}
}
// Add a marker at Taj Mahal and move the camera
// LatLng latLng = new LatLng(27.1751, 78.0421);
// MarkerOptions markerOptions = new MarkerOptions()
// .position(latLng)
// .title("Taj Mahal")
// .snippet("Wonder of the world!");
// mMap.addMarker(markerOptions);
// CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLngZoom(latLng, 16);
// mMap.animateCamera(cameraUpdate);
try {
List<Address> addresses = geocoder.getFromLocationName("uae", 1);
if (addresses.size() > 0) {
Address address = addresses.get(0);
LatLng london = new LatLng(address.getLatitude(), address.getLongitude());
MarkerOptions markerOptions = new MarkerOptions()
.position(london)
.title(address.getLocality());
mMap.addMarker(markerOptions);
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(london, 16));
}
} catch (IOException e) {
e.printStackTrace();
}
}
private void enableUserLocation() {
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;
}
mMap.setMyLocationEnabled(true);
}
private void zoomToUserLocation() {
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;
}
Task<Location> locationTask = fusedLocationProviderClient.getLastLocation();
locationTask.addOnSuccessListener(new OnSuccessListener<Location>() {
#Override
public void onSuccess(Location location) {
LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(latLng, 20));
mMap.addMarker(new MarkerOptions().position(latLng));
}
});
}
#Override
public void onMapLongClick(LatLng latLng) {
Log.d(TAG, "onMapLongClick: " + latLng.toString());
try {
List<Address> addresses = geocoder.getFromLocation(latLng.latitude, latLng.longitude, 1);
if (addresses.size() > 0) {
Address address = addresses.get(0);
String streetAddress = address.getAddressLine(0);
mMap.addMarker(new MarkerOptions()
.position(latLng)
.title(streetAddress)
.draggable(true)
);
}
} catch (IOException e) {
e.printStackTrace();
}
}
#Override
public void onMarkerDragStart(Marker marker) {
Log.d(TAG, "onMarkerDragStart: ");
}
#Override
public void onMarkerDrag(Marker marker) {
Log.d(TAG, "onMarkerDrag: ");
}
#Override
public void onMarkerDragEnd(Marker marker) {
Log.d(TAG, "onMarkerDragEnd: ");
LatLng latLng = marker.getPosition();
try {
List<Address> addresses = geocoder.getFromLocation(latLng.latitude, latLng.longitude, 1);
if (addresses.size() > 0) {
Address address = addresses.get(0);
String streetAddress = address.getAddressLine(0);
marker.setTitle(streetAddress);
}
} catch (IOException e) {
e.printStackTrace();
}
}
#Override
public void onRequestPermissionsResult(int requestCode, #NonNull String[] permissions, #NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == ACCESS_LOCATION_REQUEST_CODE) {
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
enableUserLocation();
zoomToUserLocation();
} else {
//We can show a dialog that permission is not granted...
}
}
}
}

In your onMapLongClick method you are saying mMap.addMarker(...). So of coarse you are adding new markers.
Try creating a marker object at the top of your class. And then in your onMapLongClick method, update the location (and make it visible in case you are inclined on hiding it at some point.)

java.lang.RuntimeException: Unable to start activity ComponentInfo on a null object reference [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
how to call a method in another Activity from Activity
(6 answers)
How to call a method in MainActivity from another class?
(11 answers)
Closed 12 months ago.
Hello I have this error with my code :
java.lang.NullPointerException: Attempt to invoke virtual method 'double fr.uge.bluetoothle.MapsActivity.calculDistance(double, double, double, double)' on a null object reference
I develop on Android Studio in Java.
It seems that I can't access to MapsActivity.java from MyLocationListener.java
I think I don't instantiate well my MpasActivity class.
I have this error in the folowing code MyLocationListener.java
package fr.uge.bluetoothle;
import android.location.Location;
import android.location.LocationListener;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;
import androidx.annotation.NonNull;
public class MyLocationListener implements LocationListener {
public String longitude;
public String latitude;
public double distance;
private static final String TAG = "Loca";
public MapsActivity mapsActivity;
#Override
public void onLocationChanged(#NonNull Location location) {
/*Toast.makeText(
mapsActivity.getBaseContext(),
"Location changed: Lat: " + location.getLatitude() + " Lng: "
+ location.getLongitude(), Toast.LENGTH_SHORT).show();*/
String longitude = "Longitude: " + location.getLongitude();
Log.v(TAG, longitude);
String latitude = "Latitude: " + location.getLatitude();
Log.v(TAG, latitude);
distance = mapsActivity.calculDistance(2.58622,48.84008,location.getLongitude(),location.getLatitude());
System.out.println(distance);
}
And here there is my activity's name MapsActivity.java
package fr.uge.bluetoothle;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import android.Manifest;
import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.graphics.Color;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
import com.mapbox.android.core.location.LocationEngine;
import com.mapbox.android.core.permissions.PermissionsListener;
import com.mapbox.android.core.permissions.PermissionsManager;
import com.mapbox.mapboxsdk.Mapbox;
import com.mapbox.mapboxsdk.location.LocationComponent;
import com.mapbox.mapboxsdk.location.modes.CameraMode;
import com.mapbox.mapboxsdk.maps.MapView;
import com.mapbox.mapboxsdk.maps.MapboxMap;
import com.mapbox.mapboxsdk.maps.OnMapReadyCallback;
import com.mapbox.mapboxsdk.maps.Style;
import java.util.List;
import java.lang.Math;
import com.mapbox.mapboxsdk.style.layers.CircleLayer;
import com.mapbox.mapboxsdk.style.layers.Layer;
import com.mapbox.mapboxsdk.style.layers.LineLayer;
import com.mapbox.mapboxsdk.style.layers.Property;
import com.mapbox.mapboxsdk.style.sources.VectorSource;
import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.lineCap;
import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.lineColor;
import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.lineJoin;
import static com.mapbox.mapboxsdk.style.layers.PropertyFactory.lineWidth;
public class MapsActivity extends Activity implements OnMapReadyCallback, PermissionsListener {
private MapView mapView;
private MapboxMap mapboxMap;
private PermissionsManager permissionsManager;
private LocationComponent locationComponent;
MyLocationListener myLocationListener;
private static Context mContext;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Mapbox.getInstance(this, getString(R.string.mapbox_access_token));
setContentView(R.layout.activity_maps);
mapView = findViewById(R.id.mapView);
mapView.onCreate(savedInstanceState);
mapView.getMapAsync(this);
//Display Location
LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
LocationListener locationListener = new MyLocationListener();
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.
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 1);
return;
}
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER, 5000, 1, locationListener);
Toast.makeText(
getBaseContext(),
"Location changed: Lat: " + myLocationListener.getLatitude() + " Lng: "
+ myLocationListener.getLongitude(), Toast.LENGTH_SHORT).show();
}
#Override
public void onMapReady(#NonNull MapboxMap mapboxMap) {
this.mapboxMap = mapboxMap;
mapboxMap.setStyle(getString(R.string.navigation_guidance_day), new Style.OnStyleLoaded() {
#Override
public void onStyleLoaded(#NonNull Style style) {
enableLocationComponent(style);
//Add the GPX File
VectorSource vectorSource = new VectorSource("vector-source", getString(R.string.tileset_cyclo));
style.addSource(vectorSource);
//Tracks Layer
/*CircleLayer circleLayer = new CircleLayer("circle-layer-id", "vector-source");
circleLayer.setSourceLayer("tracks");
style.addLayer(circleLayer);*/
//Waypoints Layer
CircleLayer circleLayer1 = new CircleLayer("circle-layer-id-1", "vector-source");
circleLayer1.setSourceLayer("waypoints");
style.addLayer(circleLayer1);
}
});
}
private void enableLocationComponent(Style loadMapStyle) {
/*Check if permissions are enabled and if not request*/
if (PermissionsManager.areLocationPermissionsGranted(this)) {
//Activate the MapBox LocationComponent to show user location
//Adding in LocationComponentOptions is also an optional parameter
locationComponent = mapboxMap.getLocationComponent();
locationComponent.activateLocationComponent(this, loadMapStyle);
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.
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 1);
return;
}
locationComponent.setLocationComponentEnabled(true);
//Set the component's camera mode
locationComponent.setCameraMode(CameraMode.TRACKING);
}
else {
permissionsManager = new PermissionsManager(this);
permissionsManager.requestLocationPermissions(this);
}
}
#Override
public void onExplanationNeeded(List<String> permissionsToExplain) {
Toast.makeText(this, R.string.user_location_permission_explanation, Toast.LENGTH_SHORT).show();
}
#Override
public void onPermissionResult(boolean granted) {
if (granted){
enableLocationComponent(mapboxMap.getStyle());
}
else {
Toast.makeText(this, R.string.user_location_permission_not_granted, Toast.LENGTH_SHORT).show();
}
}
#Override
public void onRequestPermissionsResult(int requestCode, #NonNull String[] permissions, #NonNull int[] grantResults) {
permissionsManager.onRequestPermissionsResult(requestCode, permissions, grantResults);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()) {
case android.R.id.home:
onBackPressed();
return true;
}
return super.onOptionsItemSelected(item);
}
#Override
protected void onStart() {
super.onStart();
mapView.onStart();
}
#Override
protected void onStop() {
super.onStop();
mapView.onStop();
}
#Override
protected void onPause() {
super.onPause();
mapView.onLowMemory();
}
#Override
protected void onDestroy() {
super.onDestroy();
mapView.onDestroy();
}
#Override
protected void onSaveInstanceState(Bundle outState){
super.onSaveInstanceState(outState);
mapView.onSaveInstanceState(outState);
}
#Override
public void onLowMemory() {
super.onLowMemory();
mapView.onLowMemory();
}
public Context getContext() {
return mContext;
}
public double calculDistance(double longitude_point, double latitude_point, double longitude_loca, double latitude_loca){
double distance;
distance = Math.acos(Math.sin(Math.toRadians(longitude_point))*Math.sin(Math.toRadians(longitude_loca))+
Math.cos(Math.toRadians(longitude_point))*Math.cos(Math.toRadians(longitude_loca))*
Math.cos(Math.toRadians(latitude_point-latitude_loca)));
distance = distance * 6371;
return distance;
}
}
I don't understand where is the problem I think That's the problem come from the transition between the activity and my other java file.

Your call to mapsActivity.calculDistance() throws an exception because the variable mapsActivity is null. You haven't set the variable mapsActivity to anything.
Looking at your code, the method calculDistance() is basically a utility method and doesn't really belong to any class (it doesn't use any methods or member variables of the class). You can simply make this a static method by adding the static keyword to the method declaration, like this:
public static double calculDistance(double longitude_point,
double latitude_point, double longitude_loca, double latitude_loca) {
Now you can use this method from any other class, like this:
distance = MapsActivity.calculDistance(2.58622,48.84008,
location.getLongitude(),location.getLatitude());
Notice that you are calling the method on the class, not on an instance of the class. In this case, you don't need to declare a variable mapsActivity, because this is no longer used.
A somewhat cleaner approach would be to move this method out of the MapsActivity class and put it in a new utility class (which should contain only public static methods and should have a private constructor so that it is not possible to actually create any instances of that utility class.

My Android App Takes Too Long To Search For Location But Doesn't Display It In The End

I was learning to develop an Android app with the GoogleMaps class. Now, in order for it function, I require the location data of the user. Now, it's all good up to this point. But whenever I install the app on my phone, the notification bar for the app shows that the app is looking for a user's location, but it takes too long to do this. In the end, however, it doesn't display it either.
Could anyone help me with this? I don't understand why this happens. I have also provided all the permissions in the manifest file as well.
For more clarity, here's the code:
#Override
public void onRequestPermissionsResult(int requestCode, #NonNull String[] permissions, #NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
}
}
}
Apart from this, there's also another bit of code, that I have used for a final confirmation from the users whether they are sure about providing/not providing their location information:
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED){
ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.ACCESS_FINE_LOCATION},1);
}
else {
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
}
Thanks for the help.
Edit - Here's the complete body of code:
package com.example.userlocation;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import android.Manifest;
import android.content.Context;
import android.content.pm.PackageManager;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
LocationManager locationManager;
LocationListener locationListener;
#Override
public void onRequestPermissionsResult(int requestCode, #NonNull String[] permissions, #NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if(grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
}
}
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
locationListener = new LocationListener() {
#Override
public void onLocationChanged(Location location) {
Toast.makeText(MainActivity.this, "User Location" + location.toString(), Toast.LENGTH_SHORT).show();
}
#Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
#Override
public void onProviderEnabled(String provider) {
}
#Override
public void onProviderDisabled(String provider) {
}
};
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED)
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION},1);
else {
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
}
}
}

Android GPS tracker returns 0.0 always

I am using the classic GPS tracker code to retrieve my current location, but I always get 0 as a return for both lat and lon, even though I try to change positions its still always 0. please note that I have used the following code in previews apps and it worked.
manifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.apostolis.map1sttest">
<!-- Permition list bellow !-->
<uses-permission android:name="android.permission.INTERNET" /> <!-- internet -->
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> <!-- internet 3g/4g enabled-->
<uses-permission android:name="android.permission.GET_ACCOUNTS" /> <!-- Google accounts -->
<uses-permission android:name="android.permission.NETWORK" /> <!-- internet -->
<uses-permission android:name="android.permission.USE_CREDENTIALS" /> <!-- Google acconts -->
<uses-permission android:name="android.permission.READ_PHONE_STATE"/> <!-- phone info -->
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> <!-- GPS -->
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/> <!-- GPS -->
<uses-feature android:name="android.hardware.location.gps" /> <!-- GPS (needed for android 5.0+) -->
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
GPStracker.java
package com.example.apostolis.map1sttest;
import android.app.AlertDialog;
import android.app.Service;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.IBinder;
import android.provider.Settings;
import android.support.annotation.Nullable;
import android.widget.Toast;
/**
* Created by Apostolis on 10/27/2016.
*/
public class GPStracker extends Service implements LocationListener {
private final Context context;
boolean isGPSEnabled = false;
boolean isNetworkEnabled = false;
boolean canGetLocation = false;
Location location;
double latitude;
double longituzzde;
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10;
private static final long MIN_TIME_BW_UPDATES = 100;
protected LocationManager locationManager;
public GPStracker(Context context){
this.context = context;
getLocation();
}
public Location getLocation(){
try {
locationManager = (LocationManager)context.getSystemService(LOCATION_SERVICE);
isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
isNetworkEnabled = locationManager.isProviderEnabled(locationManager.NETWORK_PROVIDER);
if(!isGPSEnabled && !isGPSEnabled) {
} else {
this.canGetLocation = true;
if(isNetworkEnabled) {
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
if (locationManager != null) {
location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
if(isGPSEnabled) {
if(location == null) {
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
if(locationManager != null) {
location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if(location != null){
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
return location;
}
public void stopUsingGPS(){
if(locationManager != null) {
locationManager.removeUpdates(GPStracker.this);
}
}
public double getLatitude() {
if(location != null) {
latitude = location.getLatitude();
}
return latitude;
}
public double getLongitude(){
if(location != null) {
longitude = location.getLongitude();
}
return longitude;
}
public boolean canGetLocation() {
return this.canGetLocation;
}
public void showSettingsAlert(){
AlertDialog.Builder alertDialog = new AlertDialog.Builder(context);
alertDialog.setTitle("GPS SETTINGS");
alertDialog.setMessage("GPS is not enabled.Go to Settings menu and enable it?");
alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
context.startActivity(intent);
}
}) ;
alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
alertDialog.show();
}
#Override
public void onLocationChanged(Location location) {
this.location = location;
getLatitude();
getLongitude();
}
#Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
#Override
public void onProviderEnabled(String provider) {
}
#Override
public void onProviderDisabled(String provider) {
}
#Nullable
#Override
public IBinder onBind(Intent intent) {
return null;
}
}
MainActivity.java
package com.example.apostolis.map1sttest;
import android.Manifest;
import android.content.pm.PackageManager;
import android.location.Location;
import android.location.LocationListener;
import android.support.annotation.Nullable;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;
public class MainActivity extends AppCompatActivity implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener, LocationListener {
GPStracker gps;
private String lat,lon;
Button btnGetLocation;
private GoogleApiClient mGoogleApiClient;
private LocationRequest mLocationRequest;
private double mCurrentLatitude,mCurrentLongitude;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnGetLocation = (Button) findViewById(R.id.btgps);
//creating onClick listener for GPS.
btnGetLocation.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
gps = new GPStracker(MainActivity.this);
if (gps.canGetLocation()) {
double latitude = gps.getLatitude();
double longitude = gps.getLongitude();
lat = Double.toString(latitude);
lon = Double.toString(longitude);
Toast.makeText(MainActivity.this,
"Your Location is: Lat: " + lat.toString() + " Lon:" + lon.toString(), Toast.LENGTH_LONG).show();
} else {
gps.showSettingsAlert();
}
}
});
};
#Override
public void onLocationChanged(Location location) {
}
#Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
#Override
public void onProviderEnabled(String provider) {
}
#Override
public void onProviderDisabled(String provider) {
}
#Override
public void onConnected(#Nullable Bundle bundle) {
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 = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
if (location == null) {
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, (com.google.android.gms.location.LocationListener) this);
} else {
mCurrentLatitude = location.getLatitude();
mCurrentLongitude = location.getLongitude();
Toast.makeText(this, mCurrentLongitude + " * ********"+mCurrentLatitude, Toast.LENGTH_LONG).show();
}
}
#Override
public void onConnectionSuspended(int i) {
}
#Override
public void onConnectionFailed(ConnectionResult connectionResult) {
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.apostolis.map1sttest.MainActivity">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!" />
<Button
android:text="Button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:id="#+id/btgps" />
</RelativeLayout>

implement GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener, LocationListener
in your activity and past below code in override methods
#Override
public void onConnected(#Nullable Bundle bundle) {
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 = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
if (location == null) {
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, (com.google.android.gms.location.LocationListener) this);
} else {
Toast.makeText(this, location.getLatitude() + " * ********"+location.getLongitude(), Toast.LENGTH_LONG).show();
}
}
create variables
private LocationRequest mLocationRequest;
protected GoogleApiClient mGoogleApiClient;
add this inside your onCreate method
mLocationRequest = LocationRequest.create()
.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY)
.setInterval(10 * 1000) // 10 seconds, in milliseconds
.setFastestInterval(1 * 1000); // 1 second, in milliseconds
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.addApi(Places.GEO_DATA_API)
.build();
and add this inside your onResume
if (!mGoogleApiClient.isConnected() && !mGoogleApiClient.isConnecting()) {
Log.e("Google API", "Connecting");
mGoogleApiClient.connect();
}

Why does my code keep returning "unable to get location?"

I am trying to get the user's location, but whenever I run this code it returns "unable to get location." I'm not sure why this isn't working. I'm running it on the default emulator in Android Studio. What did i do wrong?
import android.Manifest;
import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
public class MainActivity extends Activity implements LocationListener {
LocationManager locationManager;
String provider;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
provider = locationManager.getBestProvider(new Criteria(), false);
if (checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// public void requestPermissions(#NonNull String[] permissions, int requestCode)
// 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 Activity#requestPermissions for more details.
return;
}
Location location = locationManager.getLastKnownLocation(provider);
if (location != null) {
Log.i("Location Info", "Location achieved!");
} else {
Log.i("Location Info", "Unable to get location");
}
}
#Override
protected void onResume() {
super.onResume();
if (checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// public void requestPermissions(#NonNull String[] permissions, int requestCode)
// 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 Activity#requestPermissions for more details.
return;
}
locationManager.requestLocationUpdates(provider, 400, 1, this);
}
#Override
protected void onPause() {
super.onPause();
if (checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// public void requestPermissions(#NonNull String[] permissions, int requestCode)
// 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 Activity#requestPermissions for more details.
return;
}
locationManager.removeUpdates(this);
}
#Override
public void onLocationChanged(Location location) {
Double lat = location.getLatitude();
Double lng = location.getLongitude();
Log.i("Location info: Lat", lat.toString());
Log.i("Location info: Lng", lng.toString());
}
#Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
#Override
public void onProviderEnabled(String provider) {
}
#Override
public void onProviderDisabled(String provider) {
}
public void getLocation(View view) {
if (checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// public void requestPermissions(#NonNull String[] permissions, int requestCode)
// 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 Activity#requestPermissions for more details.
return;
}
Location location = locationManager.getLastKnownLocation(provider);
onLocationChanged(location);
}
}

Try this if you're using Eclipse, go to Window->Open Perspective->DDMS -> Emulator Control, then type one in Location Controls and hit Send.