Develop Reference

How to locate the nearest marker to a user?

I'm quite new to android development and I was wondering if it is possible for me to locate the nearest marker to a user and knowing which marker is closest direct the user there using a polyline and google directions api. The locations of the markers are taken from a database that I have parsed into a list array which I then use to place the markers on the map. I have tried to find help from other questions however they do not seem to fit in my project.
If it is possible for me to find the nearest marker to the user how can I do it if not is there an alternative method I could use??
This is my code for my main activity:
package com.example.defiblocator;
import android.Manifest;
import android.content.pm.PackageManager;
import android.location.Location;
import android.os.Build;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.content.ContextCompat;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.location.LocationRequest;
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.BitmapDescriptorFactory;
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 java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class MainActivity extends AppCompatActivity implements OnMapReadyCallback,
LocationListener,GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener{
public static TextView data;
public static String location;
GoogleMap mapAPI;
SupportMapFragment mapFragment;
Location mLastLocation;
Marker mCurrLocationMarker;
GoogleApiClient mGoogleApiClient;
LocationRequest mLocationRequest;
String delimiter = ",";
List<String> full = new ArrayList<>();
List<String> size = new ArrayList<>();
private ArrayList<LatLng> markerCoords = new ArrayList<LatLng>();
String info;
String name;
Double lat;
Double lng;
Button emergency;
LatLng mark;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.mapAPI);
mapFragment.getMapAsync(this);
data = findViewById(R.id.fetchdata);
new fetchData(new CallbackClass()).execute();
emergency = findViewById(R.id.button);
emergency.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
}
});
}
#Override
public void onMapReady(GoogleMap googleMap) {
mapAPI = googleMap;
mapAPI.getUiSettings().setZoomControlsEnabled(true);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
buildGoogleApiClient();
mapAPI.setMyLocationEnabled(true);
//mapAPI.setOnMyLocationChangeListener(this);
}
} else {
buildGoogleApiClient();
mapAPI.setMyLocationEnabled(true);
}
}
protected synchronized void buildGoogleApiClient() {
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API).build();
mGoogleApiClient.connect();
}
#Override
public void onConnected(Bundle bundle) {
mLocationRequest = new LocationRequest();
mLocationRequest.setInterval(1000);
mLocationRequest.setFastestInterval(1000);
mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);
if (ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
}
}
#Override
public void onConnectionSuspended(int i) {
}
#Override
public void onLocationChanged(Location location) {
/*mLastLocation = location;
if (mCurrLocationMarker != null) {
mCurrLocationMarker.remove();
}*/
//Place current location marker
LatLng patient = new LatLng(location.getLatitude(), location.getLongitude());
MarkerOptions markerOptions = new MarkerOptions();
markerOptions.position(patient);
markerOptions.title("Patient");
markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE));
mCurrLocationMarker = mapAPI.addMarker(markerOptions);
//move map camera
mapAPI.animateCamera(CameraUpdateFactory.zoomTo(11));
mapAPI.moveCamera(CameraUpdateFactory.newLatLng(patient));
//stop location updates
if (mGoogleApiClient != null) {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
}
}
#Override
public void onConnectionFailed(#NonNull ConnectionResult connectionResult) {
}
public class CallbackClass implements CallbackInterface {
#Override
public void onSuccess(String callbackData) {
info = callbackData;
full = Arrays.asList(info.split(delimiter));
size = Arrays.asList(info.split(delimiter));
Integer x = 0;
while(x != size.size()){
name = full.get(x);
x += 1;
lat = Double.valueOf(full.get(x));
x += 1;
lng = Double.valueOf(full.get(x));
x += 1;
LatLng pos = new LatLng(lat, lng);
mapAPI.addMarker(new MarkerOptions().position(pos).title(name));
mark = new LatLng(lat,lng);
markerCoords.add(mark);
}
}
#Override
public void onFailure() {
}
}
}
and this is the code for parsing the JSON from the database any help would be greatly appreciated.
package com.example.defiblocator;
import android.app.Application;
import android.os.AsyncTask;
import android.widget.TextView;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
public class fetchData extends AsyncTask <Void,Void,Void>{
CallbackInterface callbackInterface;
String data = "";
String json_url;
String singleParsed = "";
public String dataParsed = "";
String sent;
public fetchData(CallbackInterface callbackInterface) {
this.callbackInterface = callbackInterface;
}
public Integer x = 0;
#Override
protected void onPreExecute(){
json_url = "http://defiblocator.ml/json_get_data.php";
dataParsed = "";
}
#Override
protected Void doInBackground(Void... voids) {
try {
URL url = new URL(json_url);
HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection();
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
String line = "";
while(line != null){
line = bufferedReader.readLine();
data = data + line;
}
JSONArray JA = new JSONArray(data);
for(int i =0 ; i <JA.length(); i++){
JSONObject JO = (JSONObject) JA.get(i);
singleParsed = JO.get("name") + "," + JO.get("lat") + "," +JO.get("lng") + "," ;
dataParsed = dataParsed + singleParsed ;
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException | JSONException e){
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void aVoid) {
MainActivity.data.setText(dataParsed);
callbackInterface.onSuccess(dataParsed);
}
}

You could use a simple distance formula to archive this:
private Double distance(Double lat1, Double lon1, Double lat2, Double lon2) {
return Math.sqrt (Math.pow((lat1 - lat2), 2) - Math.pow((lon1 - lon2), 2));
}
// The user Location
currentLat = xxxx;
currentLon = xxxx;
if ((markerCoords != null) && (markerCoords.size() > 0)) {
LatLng near = markerCoords.get(0);
for (int x = 1; x < markerCoords.size(); x++) {
Double lat = markerCoords.get(x).latitude;
Double lon = markerCoords.get(x).longitude;
Double currentMarkerdistance = distance(
currentLat,
currentLon,
markerCoords.get(x).latitude,
markerCoords.get(x).longitude);
Double nearMarkerdistance = distance(
currentLat,
currentLon,
near.latitude,
near.longitude);
if (currentMarkerdistance < nearMarkerdistance) {
near = markerCoords.get(x);
}
}
}
// After this process the near variable will hold the near marker

how to get driving alternative routes in google map direction api v2

I just want to show driving mode alternative routes in my android app. I done a single shortest route but I want multiple driving routes.
My code is here
my mapsavtivity class
package com.example.sherazahmed.itis;
import android.content.Intent;
import android.graphics.Color;
import android.location.Location;
import android.os.AsyncTask;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;
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.MarkerOptions;
import com.google.android.gms.maps.model.PolylineOptions;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
public class onNotificationClick extends FragmentActivity implements OnMapReadyCallback {
private GoogleMap mMap;
static LatLng current=new LatLng(0,0);
static LatLng destination=new LatLng(0,0);
public void onNotificationClick(LatLng current,LatLng destination){
this.current=current;
this.destination=destination;
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_on_notification_click);
// 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);
}
#Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
mMap.addMarker(new MarkerOptions().position(current).title("current location"));
mMap.addMarker(new MarkerOptions().position(destination).title("destination"));
DownloadTask downloadTask;
String url=null;
String mode = "mode=driving";
String mode1 = "mode=bicycling";
String mode2 = "mode=walking";
url = getDirectionsUrl(current, destination,mode);
downloadTask=new DownloadTask();
// Start downloading json data from Google Directions API
downloadTask.execute(url);
//2
url = getDirectionsUrl(current, destination,mode2);
downloadTask=new DownloadTask();
// Start downloading json data from Google Directions API
downloadTask.execute(url);
//3
url = getDirectionsUrl(current, destination,mode1);
downloadTask=new DownloadTask();
// Start downloading json data from Google Directions API
downloadTask.execute(url);
}
private String getDirectionsUrl(LatLng origin,LatLng dest, String mode){
// Origin of route
String str_origin = "origin="+origin.latitude+","+origin.longitude;
// Destination of route
String str_dest = "destination="+dest.latitude+","+dest.longitude;
// Sensor enabled
String sensor = "sensor=false";
String alter="Alternative=true";
// Travelling Mode
// Building the parameters to the web service
String parameters = str_origin+"&"+str_dest+"&"+sensor+"&"+mode+"&"+alter;
// Output format
String output = "json";
// Building the url to the web service
String url = "https://maps.googleapis.com/maps/api/directions/"+output+"?"+parameters;
return url;
}
/** A method to download json data from url */
private String downloadUrl(String strUrl) throws IOException{
String data =new String();
InputStream iStream = new InputStream() {
#Override
public int read() throws IOException {
return 0;
}
};
HttpURLConnection urlConnection = null;
try{
URL url = new URL(strUrl);
// Creating an http connection to communicate with url
urlConnection = (HttpURLConnection) url.openConnection();
// Connecting to url
urlConnection.connect();
// Reading data from url
iStream = urlConnection.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(iStream));
StringBuffer sb = new StringBuffer();
String line = "";
while( ( line = br.readLine()) != null){
sb.append(line);
}
data = sb.toString();
br.close();
}catch(Exception e){
Log.d("Exception in down url", e.toString());
}finally{
iStream.close();
urlConnection.disconnect();
}
return data;
}
// Fetches data from url passed
private class DownloadTask extends AsyncTask<String, Void, String>{
// Downloading data in non-ui thread
#Override
protected String doInBackground(String... url) {
// For storing data from web service
String data =new String();
try{
// Fetching the data from web service
data = downloadUrl(url[0]);
}catch(Exception e){
Log.d("Background Task",e.toString());
}
return data;
}
// Executes in UI thread, after the execution of
// doInBackground()
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
ParserTask parserTask = new ParserTask();
// Invokes the thread for parsing the JSON data
parserTask.execute(result);
}
}
/** A class to parse the Google Places in JSON format */
private class ParserTask extends AsyncTask<String, Integer, List<List<HashMap<String,String>>> >{
// Parsing the data in non-ui thread
#Override
protected List<List<HashMap<String, String>>> doInBackground(String... jsonData) {
JSONObject jObject;
List<List<HashMap<String, String>>> routes = null;
try{
jObject = new JSONObject(jsonData[0]);
DirectionsJSONParser parser = new DirectionsJSONParser();
// Starts parsing data
routes = parser.parse(jObject);
}catch(Exception e){
e.printStackTrace();
}
return routes;
}
// Executes in UI thread, after the parsing process
#Override
protected void onPostExecute(List<List<HashMap<String, String>>> result) {
ArrayList<LatLng> points = new ArrayList<LatLng>();
PolylineOptions lineOptions = new PolylineOptions();
// Traversing through all the routes
for(int i=0;i<result.size();i++){
points = new ArrayList<LatLng>();
lineOptions = new PolylineOptions();
// Fetching i-th route
List<HashMap<String, String>> path = result.get(i);
// Fetching all the points in i-th route
for(int j=0;j<path.size();j++){
HashMap<String,String> point = path.get(j);
double lat = Double.parseDouble(point.get("lat"));
double lng = Double.parseDouble(point.get("lng"));
LatLng position = new LatLng(lat, lng);
points.add(position);
}
// Adding all the points in the route to LineOptions
lineOptions.addAll(points);
lineOptions.width(4);
// Changing the color polyline according to the mode
}
if(result.size()<1){
Toast.makeText(getBaseContext(), "No Points", Toast.LENGTH_SHORT).show();
return;
}
// Drawing polyline in the Google Map for the i-th route
mMap.addPolyline(lineOptions);
}
}
}
DirectionJSONParser class
public class DirectionsJSONParser {
/** Receives a JSONObject and returns a list of lists containing latitude and longitude */
public List<List<HashMap<String,String>>> parse(JSONObject jObject){
List<List<HashMap<String, String>>> routes = new ArrayList<List<HashMap<String,String>>>() ;
JSONArray jRoutes = null;
JSONArray jLegs = null;
JSONArray jSteps = null;
try {
jRoutes = jObject.getJSONArray("routes");
/** Traversing all routes */
for(int i=0;i<jRoutes.length();i++){
jLegs = ( (JSONObject)jRoutes.get(i)).getJSONArray("legs");
List path = new ArrayList<HashMap<String, String>>();
/** Traversing all legs */
for(int j=0;j<jLegs.length();j++){
jSteps = ( (JSONObject)jLegs.get(j)).getJSONArray("steps");
/** Traversing all steps */
for(int k=0;k<jSteps.length();k++){
String polyline = "";
polyline = (String)((JSONObject) ((JSONObject)jSteps.get(k)).get("polyline")).get("points");
List<LatLng> list = decodePoly(polyline);
/** Traversing all points */
for(int l=0;l<list.size();l++){
HashMap<String, String> hm = new HashMap<String, String>();
hm.put("lat", Double.toString(((LatLng)list.get(l)).latitude) );
hm.put("lng", Double.toString(((LatLng)list.get(l)).longitude) );
path.add(hm);
}
}
routes.add(path);
}
}
} catch (JSONException e) {
e.printStackTrace();
}catch (Exception e){
}
return routes;
}
/**
* Method to decode polyline points
* Courtesy : jeffreysambells.com/2010/05/27/decoding-polylines-from-google- maps-direction-api-with-java
* */
private List<LatLng> decodePoly(String encoded) {
List<LatLng> poly = new ArrayList<LatLng>();
int index = 0, len = encoded.length();
int lat = 0, lng = 0;
while (index < len) {
int b, shift = 0, result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lat += dlat;
shift = 0;
result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lng += dlng;
LatLng p = new LatLng((((double) lat / 1E5)),
(((double) lng / 1E5)));
poly.add(p);
}
return

String alter="Alternatives=true";
is the way to do this thing, i just forgot to place
"s" in alternative in above code !
cheers !

Calculate Time and distance and draw a path between two draggable markers in Google maps v2

Need your help!!..I am building an android app using Google API V2. I have managed to place two markers on the map and also get there location. What I mainly want to do now is to calculate their distance and time like we do in the Google maps and draw a path between them. How can I achieve that?
a-) Can I do it without using JSON? I just know JAVA not java script so help please.
b-) Who ever answer it, Please if you can, Elaborate the steps taken in the code comments?
Here is my Maps ACtivity
--
import android.app.ProgressDialog;
import android.content.Intent;
import android.content.IntentSender;
import android.graphics.Color;
import android.location.Address;
import android.location.Geocoder;
import android.location.Location;
import android.os.AsyncTask;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
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.LocationListener;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.maps.CameraUpdate;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
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.maps.model.Polyline;
import com.google.android.gms.maps.model.PolylineOptions;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
public class MapsActivity extends FragmentActivity implements
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,LocationListener,GoogleMap.OnMarkerClickListener, GoogleMap.OnInfoWindowClickListener, GoogleMap.OnMapLongClickListener, GoogleMap.OnMarkerDragListener {
private GoogleApiClient mGoogleApiClient;
private GoogleMap mMap; // Might be null if Google Play services APK is not available.
public static final String TAG = MapsActivity.class.getSimpleName();
private final static int CONNECTION_FAILURE_RESOLUTION_REQUEST = 9000;
private LocationRequest mLocationRequest;
private LocationRequest LocationDrop;
// TextView currentloc;
String filterAddress = "";
String DropoffAdress = "";
String DraggedDroppOff= "";
String dragendaddress = "";
// TextView dropOffaddress;
double currentLatitude;
double currentLongitude;
double draglat;
double draglng;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
setUpMapIfNeeded();
// tvLocInfo = (TextView) findViewById(R.id.locinfo);
mMap.setOnMapLongClickListener(this);
mMap.setOnMarkerDragListener(this);
mMap.setOnMarkerClickListener(this);
// LocationDrop = LocationRequest.create().setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY).setInterval(10 * 1000).setFastestInterval(1 * 1000);
mGoogleApiClient = new GoogleApiClient.Builder(this).addConnectionCallbacks(this).addOnConnectionFailedListener(this).addApi(LocationServices.API).build();
// Create the LocationRequest object
mLocationRequest = LocationRequest.create()
.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY)
.setInterval(10 * 1000) // 10 seconds, in milliseconds
.setFastestInterval(1 * 1000); // 1 second, in milliseconds
}
#Override
protected void onResume() {
super.onResume();
setUpMapIfNeeded();
mGoogleApiClient.connect();
}
protected void onPause() {
super.onPause();
if (mGoogleApiClient.isConnected()) {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
mGoogleApiClient.disconnect();
}
}
/**
* Sets up the map if it is possible to do so (i.e., the Google Play services APK is correctly
* installed) and the map has not already been instantiated.. This will ensure that we only ever
* call {#link #setUpMap()} once when {#link #mMap} is not null.
* <p>
* If it isn't installed {#link SupportMapFragment} (and
* {#link com.google.android.gms.maps.MapView MapView}) will show a prompt for the user to
* install/update the Google Play services APK on their device.
* <p>
* A user can return to this FragmentActivity after following the prompt and correctly
* installing/updating/enabling the Google Play services. Since the FragmentActivity may not
* have been completely destroyed during this process (it is likely that it would only be
* stopped or paused), {#link #onCreate(Bundle)} may not be called again so we should call this
* method in {#link #onResume()} to guarantee that it will be called.
*/
private void setUpMapIfNeeded() {
// Do a null check to confirm that we have not already instantiated the map.
if (mMap == null) {
// Try to obtain the map from the SupportMapFragment.
mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
.getMap();
// Check if we were successful in obtaining the map.
if (mMap != null) {
setUpMap();
}
}
}
/**
* This is where we can add markers or lines, add listeners or move the camera. In this case, we
* just add a marker near Africa.
* <p>
* This should only be called once and when we are sure that {#link #mMap} is not null.
*/
private void setUpMap() {
// mMap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Pick Me").snippet(filterAddress));
}
#Override
public void onConnected(Bundle bundle) {
Log.i(TAG, "Location services connected.");
Location location = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
if (location != null) {
// LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
handleNewLocation(location);
}
else {
handleNewLocation(location);
}
}
private void handleNewLocation(Location location) {
Log.d(TAG, location.toString());
currentLatitude = location.getLatitude();
currentLongitude = location.getLongitude();
LatLng latLng = new LatLng(currentLatitude, currentLongitude);
MarkerOptions optionsA = new MarkerOptions().position(latLng).title("Pick Me").snippet(filterAddress).icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE));
mMap.addMarker(optionsA).setDraggable(false);
mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
CameraUpdate zoom=CameraUpdateFactory.zoomTo(15);
// mMap.moveCamera(center);
mMap.animateCamera(zoom);
// mMap.setOnMarkerDragListener();
Geocoder geoCoder = new Geocoder(getBaseContext(), Locale.getDefault());
try {
List<Address> addresses = geoCoder.getFromLocation(currentLatitude,currentLongitude,1);
// List<Address> dropaddress = geoCoder.getFromLocation(laterLongitut,laterlatitude,1);
if (addresses.size() > 0) {
for (int i = 0; i < addresses.get(0).getMaxAddressLineIndex(); i++)
filterAddress += addresses.get(0).getAddressLine(i) + " ";
Log.e("My current address is 2", filterAddress );
}
}catch (IOException ex){
ex.printStackTrace();
}catch (Exception e2){
e2.printStackTrace();
}
// currentloc = (TextView) findViewById(R.id.txmarker);
// currentloc.setText("Address" + filterAddress);
Log.e("My current address is 1", filterAddress);
// Log.e("My later address is 2", DropoffAdress );
Toast.makeText(getBaseContext(),filterAddress,Toast.LENGTH_LONG).show();
}
#Override
public void onConnectionSuspended(int i) {
Log.i(TAG, "Location services suspended. Please reconnect.");
}
#Override
public void onConnectionFailed(ConnectionResult connectionResult) {
if (connectionResult.hasResolution()) {
try {
// Start an Activity that tries to resolve the error
connectionResult.startResolutionForResult(this, CONNECTION_FAILURE_RESOLUTION_REQUEST);
} catch (IntentSender.SendIntentException e) {
e.printStackTrace();
}
} else {
Log.i(TAG, "Location services connection failed with code " + connectionResult.getErrorCode());
}
}
#Override
public void onLocationChanged(Location location) {
handleNewLocation(location);
}
public void onBackPressed(){
Intent intent = new Intent(this,TurnOnGps.class);
startActivity(intent);
setContentView(R.layout.activity_turn_on_gps);
}
#Override
public void onInfoWindowClick(Marker marker) {
marker.setTitle(filterAddress);
}
#Override
public void onMapLongClick(LatLng latLng) {
MarkerOptions options2 = new MarkerOptions();
options2.position(latLng);
options2.title("Drop ME").snippet("Dragg Me ");
options2.draggable(true);
mMap.addMarker(options2);
mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
CameraUpdate zoom=CameraUpdateFactory.zoomTo(15);
Toast.makeText(getBaseContext(),"Please Drag Marker to set your Drop OFF",Toast.LENGTH_LONG).show();
// mMap.moveCamera(center);
mMap.animateCamera(zoom);
/* double updateddroplat = latLng.latitude;
double updateddroplng = latLng.longitude;
//Converting the latlngs to a string through geoencoder
LatLng latLng1 = new LatLng(updateddroplat,updateddroplng);
Geocoder geoCoder = new Geocoder(getBaseContext(), Locale.getDefault());
try {
List<Address> addresses = geoCoder.getFromLocation(updateddroplat,updateddroplng,1);
if(addresses.size() > 0){
for (int i=0; i < addresses.get(0).getMaxAddressLineIndex(); i++)
DropoffAdress += addresses.get(0).getAddressLine(i) + "";
Log.e("My DroppOff Location is" , DropoffAdress);
}
}catch (IOException ex){
ex.printStackTrace();
}catch (Exception e2){
e2.printStackTrace();
}
Log.e("My DropOff Location is" , DropoffAdress);
Toast.makeText(getBaseContext(),DropoffAdress,Toast.LENGTH_LONG).show();
*/
}
#Override
public void onMarkerDragStart(Marker marker) {
marker.setSnippet("Please Drag me to set your Drop OFF");
}
#Override
public void onMarkerDrag(Marker marker) {
}
#Override
public void onMarkerDragEnd(Marker marker) {
DropoffAdress = dragendaddress;
Log.e("My DroppOff Location is" , DraggedDroppOff);
LatLng dragposition = marker.getPosition();
draglat = dragposition.latitude;
draglng = dragposition.longitude;
LatLng latLng1 = new LatLng(draglat, draglng);
marker.getId();
// marker.getSnippet();
marker.setSnippet(dragendaddress);
marker.setTitle("Drop ME");
Geocoder geoCoder = new Geocoder(getBaseContext(), Locale.getDefault());
try {
List<Address> addresses = geoCoder.getFromLocation(draglat,draglng,1);
if(addresses.size() > 0){
for (int i=0; i < addresses.get(0).getMaxAddressLineIndex(); i++){
dragendaddress += addresses.get(0).getAddressLine(i) + "";
Log.e("My DroppOff Location is", dragendaddress);
}
Toast.makeText(getBaseContext(),dragendaddress,Toast.LENGTH_LONG).show();
}
}catch (IOException ex){
ex.printStackTrace();
}catch (Exception e2){
e2.printStackTrace();
}
}
#Override
public boolean onMarkerClick(Marker marker ) {
Log.e("am in markerclick event","");
String Title = marker.getTitle();
String Snippet = marker.getSnippet();
Log.e("I am in onMarkerClick", Title);
if(Title.equals("Pick Me")){
marker.setSnippet(filterAddress);
Toast.makeText(getBaseContext(),filterAddress,Toast.LENGTH_LONG).show();
Log.e("I am in onMarkerClick", Title);
}else if(Title.equals("Drop ME")){
marker.setSnippet(dragendaddress);
Toast.makeText(getBaseContext(),dragendaddress,Toast.LENGTH_LONG).show();
}
try {
Polyline polyline = mMap.addPolyline(new PolylineOptions().add(new LatLng(currentLatitude, currentLongitude), new LatLng(draglat, draglng)).width(10).color(Color.RED));
}catch (Exception e){
e.printStackTrace();
}
return false;
}

calculating the distance ::
public float distance (LatLng point1, LatLng point2 )
{
double earthRadius = 3958.75;
double latDiff = Math.toRadians(point2.latitude - point1.latitude);
double lngDiff = Math.toRadians(point2.longitude - point2.longitude);
double a = Math.sin(latDiff /2) * Math.sin(latDiff /2) +
Math.cos(Math.toRadians(point1.latitude)) * Math.cos(Math.toRadians(point2.latitude)) *
Math.sin(lngDiff /2) * Math.sin(lngDiff /2);
double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
double distance = earthRadius * c;
int meterConversion = 1609;
return new Float(distance).floatValue();
}
and to draw a line add the points to a list then use the polyline function .

Ok Firstly thanks all you guys for being a support. I finally got the solution to my problem with blessings and a bit of my own RND..
http://wptrafficanalyzer.in/blog/route-between-two-locations-with-waypoints-in-google-map-android-api-v2/
This greatly solved the Direction Parsing issue.
And i molded my code and added the methods from the Maps activity and JSON class.
Which solved the problem.
Happy :)
Thanks for taking the time..
+Any one having the same issue can post there problem in the comments i would try to answer it. Through what ever small i have learnt from solving this problem..

You can use code here. In this code distanceText gives distance between two points and timeText gives travelling time.

java.lang.nullpointerexception attempt to invoke method 'int java.util.List.size()' [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 2 years ago.
Main Activity
trying to add google map please help as soon as u can
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import org.json.JSONObject;
import android.app.ActionBar;
import android.content.Intent;
import android.graphics.Color;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
import com.google.android.gms.maps.model.PolylineOptions;
import com.parse.ParseAnalytics;
import com.parse.ParseUser;
public class OnscreenActivity extends FragmentActivity {
private static final LatLng sydney = new LatLng(30.8894669, 75.8246729);
private static final LatLng connct = new LatLng(30.8914863, 75.874398);
GoogleMap googleMap;
final String TAG1 = "PathGoogleMapActivity";
public static final String TAG = OnscreenActivity.class.getSimpleName();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_map);
SupportMapFragment fm = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.fragment1);
googleMap = fm.getMap();
ParseAnalytics.trackAppOpened(getIntent());
ParseUser currentUser = ParseUser.getCurrentUser();
if (currentUser == null) {
navigateToLogin();
} else {
Log.i(TAG, currentUser.getUsername());
}
ActionBar actionbar = getActionBar();
actionbar.show();
MarkerOptions options = new MarkerOptions();
options.position(sydney);
options.position(connct);
googleMap.addMarker(options);
String url = getMapsApiDirectionsUrl();
ReadTask downloadTask = new ReadTask();
downloadTask.execute(url);
googleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(connct, 16));
addMarkers();
}
private void addMarkers() {
// TODO Auto-generated method stub
if (googleMap != null) {
googleMap.addMarker(new MarkerOptions().position(sydney).title(
"First Point"));
googleMap.addMarker(new MarkerOptions().position(connct).title(
"Second Point"));
}
}
private String getMapsApiDirectionsUrl() {
String waypoints = "waypoints=optimize:true|" + sydney.latitude + ","
+ sydney.longitude + "|" + "|" + connct.latitude + ","
+ connct.longitude;
String sensor = "sensor=false";
String params = waypoints + "&" + sensor;
String output = "json";
String url = "https://maps.googleapis.com/maps/api/directions/"
+ output + "?" + params;
return url;
}
private class ReadTask extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String... url) {
String data = "";
try {
HttpConnection http = new HttpConnection();
data = http.readUrl(url[0]);
} catch (Exception e) {
Log.d("Background Task", e.toString());
}
return data;
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
new ParserTask().execute(result);
}
}
private class ParserTask extends
AsyncTask<String, Integer, List<List<HashMap<String, String>>>> {
#Override
protected List<List<HashMap<String, String>>> doInBackground(
String... jsonData) {
JSONObject jObject;
List<List<HashMap<String, String>>> routes = null;
try {
jObject = new JSONObject(jsonData[0]);
PathJsonParser parser = new PathJsonParser();
routes = parser.parse(jObject);
} catch (Exception e) {
e.printStackTrace();
}
return routes;
}
#Override
protected void onPostExecute(List<List<HashMap<String, String>>> routes) {
ArrayList<LatLng> points = null;
PolylineOptions polyLineOptions = null;
// traversing through routes
for (int i = 0; i < routes.size(); i++) {
points = new ArrayList<LatLng>();
polyLineOptions = new PolylineOptions();
List<HashMap<String, String>> path = routes.get(i);
for (int j = 0; j < path.size(); j++) {
HashMap<String, String> point = path.get(j);
double lat = Double.parseDouble(point.get("lat"));
double lng = Double.parseDouble(point.get("lng"));
LatLng position = new LatLng(lat, lng);
points.add(position);
}
polyLineOptions.addAll(points);
polyLineOptions.width(2);
polyLineOptions.color(Color.BLUE);
}
googleMap.addPolyline(polyLineOptions);
}
}
private void navigateToLogin() {
Intent intent = new Intent(this, Login.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(intent);
}
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.map, menu);
return true;
}
public boolean onOptionsItemSelected(MenuItem item) {
int itemId = item.getItemId();
if (itemId == R.id.action_logout) {
ParseUser.logOut();
navigateToLogin();
}
if (itemId == R.id.options) {
Intent intent = new Intent(this, UserOptions.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(intent);
}
return super.onOptionsItemSelected(null);
}
}

It is impossible for us to tell you exactly why the routes List is null in your onPostExecute in the ParserTask, but it is.
If it is intended that your doInBackground in ParserTask can return null, you should at least check if the routes variable is null before you attempt to do anything with it. This will not fix the error and might result in your app not doing what it should, but as I mentioned previously, it's impossible to tell you any more without the full log.
if (routes == null) return; will suppress the error, but only solve your problem if you read multiple json files and some of them actually parse.

Android collect and send data

I am working on application where I need to collect accelerometer and location data & send them over web-server. I have to collect the data on sensor changed event. Right now I am trying to collect it when I click on start button, but somehow I don't see that data getting stored in my file. Could anyone help me with this ?
I have to send this data to MySQL database for processing (on web-server). How will I send the data over to server?
Here is what I have tried right now :
package myapp;
import java.io.*;
import java.util.ArrayList;
import java.util.List;
import app.AccelLocData;
import com.google.android.gms.maps.*;
import com.google.android.gms.maps.GoogleMap.OnMapClickListener;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.Dialog;
import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
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.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
public class MapViewActivity extends Activity implements LocationListener,
SensorEventListener, OnClickListener {
GoogleMap googleMap;
private boolean started = false;
private ArrayList<AccelLocData> sensorData;
private SensorManager sensorManager;
private Button btnStart, btnStop;
private String provider;
// private Button btnUpload;
#SuppressLint("NewApi")
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
sensorData = new ArrayList<AccelLocData>();
btnStart = (Button) findViewById(R.id.btnStart);
btnStop = (Button) findViewById(R.id.btnStop);
btnStart.setOnClickListener(this);
btnStop.setOnClickListener(this);
btnStart.setEnabled(true);
btnStop.setEnabled(false);
int status = GooglePlayServicesUtil
.isGooglePlayServicesAvailable(getBaseContext());
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
googleMap.setOnMapClickListener(new OnMapClickListener() {
#Override
public void onMapClick(LatLng latLng) {
// Creating a marker
MarkerOptions markerOptions = new MarkerOptions();
// Setting the position for the marker
markerOptions.position(latLng);
// Setting the title for the marker.
// This will be displayed on taping the marker
markerOptions.title(latLng.latitude + " : "
+ latLng.longitude);
// Clears the previously touched position
googleMap.clear();
// Animating to the touched position
googleMap.animateCamera(CameraUpdateFactory
.newLatLng(latLng));
// Placing a marker on the touched position
googleMap.addMarker(markerOptions);
}
});
// Enabling MyLocation Layer of Google Map
googleMap.setMyLocationEnabled(true);
LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
Criteria criteria = new Criteria();
provider = locationManager.getBestProvider(criteria, true);
Location location = locationManager.getLastKnownLocation(provider);
if (location != null) {
onLocationChanged(location);
}
locationManager.requestLocationUpdates(provider, 20000, 0, this);
}
}
public void onSensorChanged(SensorEvent event) {
if (started) {
double x = event.values[0];
double y = event.values[1];
double z = event.values[2];
long timestamp = System.currentTimeMillis();
LocationManager locManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
criteria.setPowerRequirement(Criteria.POWER_MEDIUM);
criteria.setAccuracy(Criteria.ACCURACY_FINE);
provider = locManager.getBestProvider(criteria, true);
Location location = locManager.getLastKnownLocation(provider);
double latitude = 0;
double longitude = 0;
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
AccelLocData data = new AccelLocData(timestamp, x, y, z, latitude,
longitude);
// System.out.println("Accel Data:" + data.toString());
// System.out.println("Latitude:" + latitude);
// System.out.println("Longitude:" + longitude);
sensorData.add(data);
}
}
#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));
System.out.println("Latitude:" + latitude + ", Longitude:" + longitude);
// Setting latitude and longitude in the TextView tv_location
// tvLocation.setText("Latitude:" + latitude + ", Longitude:" +
// longitude);
}
#Override
public void onProviderDisabled(String arg0) {
// 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 void onAccuracyChanged(Sensor arg0, int arg1) {
// TODO Auto-generated method stub
}
#Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btnStart:
btnStart.setEnabled(false);
btnStop.setEnabled(true);
// btnUpload.setEnabled(false);
// sensorData = new ArrayList<AccelLocData>();
// save prev data if available
started = true;
try {
File root = android.os.Environment
.getExternalStorageDirectory();
File dir = new File(root.getAbsolutePath() + "/myapp");
dir.mkdirs();
File sensorFile = new File(dir, "acc.txt");
// sensorFile.createNewFile();
FileOutputStream fOut = new FileOutputStream(sensorFile);
ObjectOutputStream myOutWriter = new ObjectOutputStream(fOut);
System.out.println("Sensor data size:"+sensorData.size());
for(int i=0;i<sensorData.size();i++){
System.out.println("Sensor Data:" + sensorData.get(i).getX());
}
myOutWriter.writeObject(sensorData);
myOutWriter.close();
fOut.close();
} catch (Exception e) {
}
Sensor accel = sensorManager
.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
sensorManager.registerListener(this, accel,
SensorManager.SENSOR_DELAY_FASTEST);
break;
case R.id.btnStop:
btnStart.setEnabled(true);
btnStop.setEnabled(false);
// btnUpload.setEnabled(true);
started = false;
sensorManager.unregisterListener(this);
// don't need chart
// openChart();
// show data in chart
break;
// case R.id.btnUpload:
// break;
default:
break;
}
}
}

In your activity put this into your OnClick of your Startbutton:
startService(new Intent(this, BackgroundService.class));
and this to your Stopbutton:
stopService(new Intent(this, BackgroundService.class));
Create a new Class for example like the following:
public class BackgroundService extends Service implements LocationListener,
SensorEventListener{
//Hint: there are some methods you need to implement which I forgot to mention but eclipse will add them for you
#Override
public void onCreate() {
//enable networking, look into this: http://www.vogella.com/blog/2012/02/22/android-strictmode-networkonmainthreadexception/
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
//do your data collecting-methods and connect to your webserver
}
#Override
public void onDestroy() {
//unregister your sensor listener
}
}
In this method I got this:
#Override
public void onSensorChanged(SensorEvent event) {
sendValuesToYourServer(Float.toString(event.values[0]) + "," + Float.toString(event.values[1]) +","+ Float.toString(event.values[2]));
}