[Android Studio] LemonKicks:
Hi everyone,

I'm working on my first app (still a noob) with Google Maps API v2 in Android Studio and followed a couple of tutorials to get the user's current position and draw a path between two points (not working right now). I am using Retrofit to parse JSON. Now I have a current position and when the user taps the screen, a green marker appears and when the user taps again a red marker appears. Clicking on my driving button to get the route between red and green does nothing.

I would like the current position of the user also to be the starting point (so no extra markers). A user has to be able to enter an address and a new marker has to be set at that address. A route should be drawn between the current position of the user and the new address (showing distance and time) Like Runkeeper, I would like that - when the user moves - the marker at the current position moves with him.

I just can't find any good up to date tutorials which I can use to create this? Is someone able to help me or could someone look at my code? Or know any good tutorials?

package com.lemonkicks.trackmycab.trackmycab;

import android.Manifest;
import android.content.pm.PackageManager;
import android.graphics.Color;
import android.location.Location;
import android.os.Build;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.support.v4.content.ContextCompat;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import com.lemonkicks.trackmycab.trackmycab.POJO.Example;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GoogleApiAvailability;
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 com.google.android.gms.maps.model.Polyline;
import com.google.android.gms.maps.model.PolylineOptions;

import java.util.ArrayList;
import java.util.List;

import retrofit.Call;
import retrofit.Callback;
import retrofit.GsonConverterFactory;
import retrofit.Response;
import retrofit.Retrofit;

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback,
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,
LocationListener {

private GoogleMap mMap;
GoogleApiClient mGoogleApiClient;
Location mLastLocation;
Marker mCurrLocationMarker;
LocationRequest mLocationRequest;
LatLng origin;
LatLng dest;
ArrayList<LatLng> MarkerPoints;
TextView ShowDistanceDuration;
Polyline line;

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

ShowDistanceDuration = (TextView) findViewById(R.id.show_distance_time);

if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
checkLocationPermission();
}

// Initializing
MarkerPoints = new ArrayList<>();

//show error dialog if Google Play Services not available
if (!isGooglePlayServicesAvailable()) {
Log.d("onCreate", "Google Play Services not available. Ending Test case.");
finish();
} else {
Log.d("onCreate", "Google Play Services available. Continuing.");
}

// 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);
}

/**
* 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;

// Setting onclick event listener for the map
mMap.setOnMapClickListener(new GoogleMap.OnMapClickListener() {

@Override
public void onMapClick(LatLng point) {

// clearing map and generating new marker points if user clicks on map more than two times
if (MarkerPoints.size() > 1) {
mMap.clear();
MarkerPoints.clear();
MarkerPoints = new ArrayList<>();
ShowDistanceDuration.setText("");
}

// Adding new item to the ArrayList
MarkerPoints.add(point);
Log.i("onMapClick", "Map clicked, number of points is now " + MarkerPoints.size());

// Creating MarkerOptions
MarkerOptions options = new MarkerOptions();

// Setting the position of the marker
options.position(point);

/**
* For the start location, the color of marker is GREEN and
* for the end location, the color of marker is RED.
*/
if (MarkerPoints.size() == 1) {
options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN));
} else if (MarkerPoints.size() == 2) {
options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED));
}

// Add new marker to the Google Map Android API V2
mMap.addMarker(options);

// Checks, whether start and end locations are captured
if (MarkerPoints.size() >= 2) {
origin = MarkerPoints.get(0);
dest = MarkerPoints.get(1);
Log.i("onMapClick", "origin and dest now set.");
} else {
Log.i("onMapClick", "origin and dest not set as number of marker points is " + MarkerPoints.size());
}

}
});

Button btnDriving = (Button) findViewById(R.id.btnDriving);
btnDriving.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
build_retrofit_and_get_response("driving");
}
});

Button btnWalk = (Button) findViewById(R.id.btnWalk);
btnWalk.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
build_retrofit_and_get_response("walking");
}
});

//Initialize Google Play Services
if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
buildGoogleApiClient();
mMap.setMyLocationEnabled(true);
}
} else {
buildGoogleApiClient();
mMap.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 latLng = new LatLng(location.getLatitude(), location.getLongitude());
MarkerOptions markerOptions = new MarkerOptions();
markerOptions.position(latLng);
markerOptions.title("Current Position");
markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_MAGENTA));
mCurrLocationMarker = mMap.addMarker(markerOptions);

//move map camera
mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
mMap.animateCamera(CameraUpdateFactory.zoomTo(11));

//stop location updates
if (mGoogleApiClient != null) {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
}

}

@Override
public void onConnectionFailed(ConnectionResult connectionResult) {

}

private void build_retrofit_and_get_response(String type) {

String url = "https://maps.googleapis.com/maps/";

Retrofit retrofit = new Retrofit.Builder()
.baseUrl(url)
.addConverterFactory(GsonConverterFactory.create())
.build();

RetrofitMaps service = retrofit.create(RetrofitMaps.class);

Call<Example> call = service.getDistanceDuration("metric", origin.latitude + "," + origin.longitude,dest.latitude + "," + dest.longitude, type);

call.enqueue(new Callback<Example>() {
@Override
public void onResponse(Response<Example> response, Retrofit retrofit) {

try {
//Remove previous line from map
if (line != null) {
line.remove();
}
// This loop will go through all the results and add marker on each location.
for (int i = 0; i < response.body().getRoutes().size(); i++) {
String distance = response.body().getRoutes().get(i).getLegs().get(i).getDistance().getText();
String time = response.body().getRoutes().get(i).getLegs().get(i).getDuration().getText();
ShowDistanceDuration.setText("Distance:" + distance + ", Duration:" + time);
String encodedString = response.body().getRoutes().get(0).getOverviewPolyline().getPoints();
List<LatLng> list = decodePoly(encodedString);
line = mMap.addPolyline(new PolylineOptions()
.addAll(list)
.width(20)
.color(Color.RED)
.geodesic(true)
);
}
} catch (Exception e) {
Log.d("onResponse", "There is an error");
e.printStackTrace();
}
}

@Override
public void onFailure(Throwable t) {
Log.d("onFailure", t.toString());
}
});

}

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 poly;
}

// Checking if Google Play Services Available or not
private boolean isGooglePlayServicesAvailable() {
GoogleApiAvailability googleAPI = GoogleApiAvailability.getInstance();
int result = googleAPI.isGooglePlayServicesAvailable(this);
if(result != ConnectionResult.SUCCESS) {
if(googleAPI.isUserResolvableError(result)) {
googleAPI.getErrorDialog(this, result,
0).show();
}
return false;
}
return true;
}

public static final int MY_PERMISSIONS_REQUEST_LOCATION = 99;
public boolean checkLocationPermission(){
if (ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {

// Asking user if explanation is needed
if (ActivityCompat.shouldShowRequestPermissionRationale(this,
Manifest.permission.ACCESS_FINE_LOCATION)) {

// Show an explanation to the user *asynchronously* -- don't block
// this thread waiting for the user's response! After the user
// sees the explanation, try again to request the permission.

//Prompt the user once explanation has been shown
ActivityCompat.requestPermissions(this,
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
MY_PERMISSIONS_REQUEST_LOCATION);

} else {
// No explanation needed, we can request the permission.
ActivityCompat.requestPermissions(this,
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
MY_PERMISSIONS_REQUEST_LOCATION);
}
return false;
} else {
return true;
}
}

}