Step 1 :- Create New Android Project.

Step 2 :- Add Google-play-services_lib to your project.

Step 3 :- Open AndroidManifest.xml file.

<!--?xml version="1.0" encoding="utf-8"?-->
package="com.mapv2.demo"
android:versionCode="1"
android:versionName="1.0" &gt;

&lt;uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" /&gt;

&nbsp;

&lt;permission
android:name="com.mapv2.demo.permission.MAPS_RECEIVE"
android:protectionLevel="signature" /&gt;

&nbsp;

&nbsp;

&lt;uses-feature
android:glEsVersion="0x00020000"
android:required="true"/&gt;

&lt;application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" &gt;
&lt;activity
android:name="com.mapv2.demo.MainActivity"
android:label="@string/app_name" &gt;
&nbsp;

&lt;meta-data
android:name="com.google.android.maps.v2.API_KEY"
android:value="AIzaSyCmX7SLVHXxU9pSqb2QbAOvdnjAGUulOrk"/&gt;

&nbsp;

Step 4 :- Open activity_main.xml.

xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >

<RadioGroup
android:id="@+id/rg_modes"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:orientation="horizontal"

>

android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/str_rb_driving"
android:checked="true" />

android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/str_rb_bicycling" />

android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/str_rb_walking" />

 

<fragment
android:id="@+id/map"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@id/rg_modes"
class="com.google.android.gms.maps.SupportMapFragment" />

Step 5 :- Open MainActivity.java

package com.mapv2.demo;

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;
import java.util.List;

import org.json.JSONObject;

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.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.RadioGroup.OnCheckedChangeListener;
import android.widget.Toast;

import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.GoogleMap.OnMapClickListener;
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.MarkerOptions;
import com.google.android.gms.maps.model.PolylineOptions;

public class MainActivity extends FragmentActivity {

GoogleMap map;
RadioButton rbDriving;
RadioButton rbBiCycling;
RadioButton rbWalking;
RadioGroup rgModes;
ArrayList markerPoints;
int mMode=0;
final int MODE_DRIVING=0;
final int MODE_BICYCLING=1;
final int MODE_WALKING=2;

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

// Getting reference to rb_driving
rbDriving = (RadioButton) findViewById(R.id.rb_driving);

// Getting reference to rb_bicylcing
rbBiCycling = (RadioButton) findViewById(R.id.rb_bicycling);

// Getting reference to rb_walking
rbWalking = (RadioButton) findViewById(R.id.rb_walking);

// Getting Reference to rg_modes
rgModes = (RadioGroup) findViewById(R.id.rg_modes);

rgModes.setOnCheckedChangeListener(new OnCheckedChangeListener() {

@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {

// Checks, whether start and end locations are captured
if(markerPoints.size() >= 2){
LatLng origin = markerPoints.get(0);
LatLng dest = markerPoints.get(1);

// Getting URL to the Google Directions API
String url = getDirectionsUrl(origin, dest);

DownloadTask downloadTask = new DownloadTask();

// Start downloading json data from Google Directions API
downloadTask.execute(url);
}
}
});

// Initializing
markerPoints = new ArrayList();

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

// Getting Map for the SupportMapFragment
map = fm.getMap();

// Enable MyLocation Button in the Map
map.setMyLocationEnabled(true);

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

@Override
public void onMapClick(LatLng point) {

// Already two locations
if(markerPoints.size()>1){
markerPoints.clear();
map.clear();
}

// Adding new item to the ArrayList
markerPoints.add(point);

// Draws Start and Stop markers on the Google Map
drawStartStopMarkers();

// Checks, whether start and end locations are captured
if(markerPoints.size() >= 2){
LatLng origin = markerPoints.get(0);
LatLng dest = markerPoints.get(1);

// Getting URL to the Google Directions API
String url = getDirectionsUrl(origin, dest);

DownloadTask downloadTask = new DownloadTask();

// Start downloading json data from Google Directions API
downloadTask.execute(url);
}

}
});
}

// Drawing Start and Stop locations
private void drawStartStopMarkers(){

for(int i=0;i<markerPoints.size();i++){

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

// Setting the position of the marker
options.position(markerPoints.get(i) );

/**
* For the start location, the color of marker is GREEN and
* for the end location, the color of marker is RED.
*/
if(i==0){
options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN));
}else if(i==1){
options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED));
}

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

private String getDirectionsUrl(LatLng origin,LatLng dest){

// 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";

// Travelling Mode
String mode = "mode=driving";

if(rbDriving.isChecked()){
mode = "mode=driving";
mMode = 0 ;
}else if(rbBiCycling.isChecked()){
mode = "mode=bicycling";
mMode = 1;
}else if(rbWalking.isChecked()){
mode = "mode=walking";
mMode = 2;
}

// Building the parameters to the web service
String parameters = str_origin+"&"+str_dest+"&"+sensor+"&"+mode;

// 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 = "";
InputStream iStream = null;
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 while downloading 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 = "";

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 points = null;
PolylineOptions lineOptions = null;
MarkerOptions markerOptions = new MarkerOptions();

// Traversing through all the routes
for(int i=0;i<result.size();i++){
points = new ArrayList();
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(2);

// Changing the color polyline according to the mode
if(mMode==MODE_DRIVING)
lineOptions.color(Color.RED);
else if(mMode==MODE_BICYCLING)
lineOptions.color(Color.GREEN);
else if(mMode==MODE_WALKING)
lineOptions.color(Color.BLUE);
}

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
map.addPolyline(lineOptions);

}
}

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

1.) DirectionsJSONParser.java

package com.mapv2.demo;

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

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

import com.google.android.gms.maps.model.LatLng;

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 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 decodePoly(String encoded) {

List poly = new ArrayList();
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;
}
}

Step 6 :- Run Code.