How To Draw Shortest Path Between Two Points in Google Map

Diagram

"The following description is based on the Google older API version ."

     New Version(Google Maps Android API v2 ) 

 Step 1

    Add New Class to Your Project call ShareData .And Type Following Code.

package com.sha;

public class SharedData {

      

    // this is a singleton class that provides a global data share for all of the

    // activities and services in the MDWrapper application      

    private static SharedData instance = null;

    private SharedData() {

        //randomizeServers();

    }

  

    // data to be shared

    private String APIKEY = "";

    private double src_lat = -1;

    private double src_lng = -1;

    private double dest_lat = -1;

    private double dest_lng = -1;

  

   

    public String getAPIKEY() {

        return APIKEY;

    }

   

    public void setAPIKEY(String aPIKEY) {

        APIKEY = aPIKEY;

    }

    

    public double getSrc_lat() {

        return src_lat;

    }

  

    public void setSrc_lat(double src_lat) {

        this.src_lat = src_lat;

    }

   

    public double getSrc_lng() {

        return src_lng;

    }

   

    public void setSrc_lng(double src_lng) {

        this.src_lng = src_lng;

    }

   

    public double getDest_lat() {

        return dest_lat;

    }

    public void setDest_lat(double dest_lat) {

        this.dest_lat = dest_lat;

    }

  

    public double getDest_lng() {

        return dest_lng;

    }

   

    public void setDest_lng(double dest_lng) {

        this.dest_lng = dest_lng;

    }

    public static SharedData getInstance() {

        if (null == instance) {

            instance = new SharedData();

        }

        return instance;

    }

}

-----------------------------------------------------------------------------

Step 2

Add  another class call CustomItemizedOverlay. And type following code.

package com.sha;

import java.util.ArrayList;

import android.graphics.drawable.Drawable;

import com.google.android.maps.ItemizedOverlay;

import com.google.android.maps.OverlayItem;

public class CustomItemizedOverlay extends ItemizedOverlay<OverlayItem> {

       private final ArrayList<OverlayItem> mapOverlays = new ArrayList<OverlayItem>();

       public CustomItemizedOverlay(Drawable defaultMarker) {

             

           super(boundCenterBottom(defaultMarker));

       }

       @Override

       protected OverlayItem createItem(int i) {

           return mapOverlays.get(i);

       }

       @Override

       public int size() {

           return mapOverlays.size();

       }

       public void addOverlay(OverlayItem overlay) {

           mapOverlays.add(overlay);

           this.populate();

       }

       }

 --------------------------------------------------------------------------------------------------------

Step3

Add  another class call MyOverlay. And type following code.

package com.sha;

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Paint;

import android.graphics.Point;

import com.google.android.maps.GeoPoint;

import com.google.android.maps.MapView;

import com.google.android.maps.Overlay;

import com.google.android.maps.Projection;

public class MyOverLay extends Overlay

{

    private GeoPoint gp1;

    private GeoPoint gp2;

    private int mode=0;

    private int defaultColor;

    Context mContext;

    public MyOverLay(Context context,GeoPoint gp1,GeoPoint gp2,int mode) // GeoPoint is a int. (6E)

    {

        this.gp1 = gp1;

        this.gp2 = gp2;

        this.mode = mode;

        this.mContext = context;

        defaultColor = 999; // no defaultColor

    }

    public MyOverLay(GeoPoint gp1,GeoPoint gp2,int mode, int defaultColor)

    {

        this.gp1 = gp1;

        this.gp2 = gp2;

        this.mode = mode;

        this.defaultColor = defaultColor;

    }

    public int getMode()

    {

        return mode;

    }

    @Override

    public boolean draw

    (Canvas canvas, MapView mapView, boolean shadow, long when)

    {

        Projection projection = mapView.getProjection();

        if (shadow == false)

        {

            Paint paint = new Paint();

            paint.setAntiAlias(true);

            Point point = new Point();

            projection.toPixels(gp1, point);

            // mode=1&#65306;start

            if(mode==1)

            {

                if(defaultColor==999)

                    paint.setColor(Color.BLUE);

                else

                    paint.setColor(defaultColor);              

                // start point

            }

            // mode=2&#65306;path

            else if(mode==2)

            {

                if(defaultColor==999)

                    paint.setColor(Color.RED);

                else

                    paint.setColor(defaultColor);

                Point point2 = new Point();

                projection.toPixels(gp2, point2);

                paint.setStrokeWidth(5);

                paint.setAlpha(120);

                canvas.drawLine(point.x, point.y, point2.x,point2.y, paint);

              

            }

            /* mode=3&#65306;end */

            else if(mode==3)

            {

                /* the last path */

                if(defaultColor==999)

                    paint.setColor(Color.GREEN);

                else

                    paint.setColor(defaultColor);

                Point point2 = new Point();

                projection.toPixels(gp2, point2);

                paint.setStrokeWidth(5);

                paint.setAlpha(120);

                canvas.drawLine(point.x, point.y, point2.x,point2.y, paint);

                /* end point */

              

            }

        }

        return super.draw(canvas, mapView, shadow, when);

    }

}

Step 4

Add  another class call RoutePath. And type following code.

package com.sha;

import java.io.IOException;

import java.net.HttpURLConnection;

import java.net.MalformedURLException;

import java.net.URL;

import java.util.ArrayList;

import java.util.List;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;

import org.w3c.dom.Element;

import org.w3c.dom.Node;

import org.w3c.dom.NodeList;

import org.xml.sax.SAXException;

import android.app.AlertDialog;

import android.app.ProgressDialog;

import android.content.DialogInterface;

import android.graphics.Color;

import android.graphics.drawable.Drawable;

import android.os.AsyncTask;

import android.os.Bundle;

import android.util.Log;

import com.google.android.maps.GeoPoint;

import com.google.android.maps.MapActivity;

import com.google.android.maps.MapView;

import com.google.android.maps.Overlay;

import com.google.android.maps.OverlayItem;

//import com.sha.SharedDataActivity.connectAsyncTask;

public class RoutePath extends MapActivity {

    /** Called when the activity is first created. */

    MapView mapView;

    private RoutePath _activity;

    GeoPoint srcGeoPoint,destGeoPoint;

    private static List<Overlay> mOverlays;

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        SharedData data = SharedData.getInstance();

        mapView = new MapView(this,data.getAPIKEY());

        mapView.setClickable(true);      

        setContentView(mapView);

        _activity = this;

        double src_lat = data.getSrc_lat();

        double src_long = data.getSrc_lng();

        double dest_lat = data.getDest_lat();

        double dest_long = data.getDest_lng();

        if(src_lat == -1 || src_long == -1 || dest_lat == -1 || dest_long == -1){

            showAlert("Please enter source and destination points");

        }else{

            srcGeoPoint = new GeoPoint((int) (src_lat * 1E6),(int) (src_long * 1E6));

            destGeoPoint = new GeoPoint((int) (dest_lat * 1E6),(int) (dest_long * 1E6));

            List<Overlay> mapOverlays = mapView.getOverlays();

            Drawable srcdrawable = this.getResources().getDrawable(R.drawable.ic_launcher);

            CustomItemizedOverlay srcitemizedOverlay = new CustomItemizedOverlay(srcdrawable);

            //CustomItemizedOverlay srcitemizedOverlay = new CustomItemizedOverlay(getDrawable("com/agarwal/route/pin_green.png"));

            OverlayItem srcoverlayitem = new OverlayItem(srcGeoPoint, "Hello!", "This is your Location.");

            Drawable destdrawable = this.getResources().getDrawable(R.drawable.ic_launcher);

            CustomItemizedOverlay  destitemizedOverlay = new CustomItemizedOverlay( destdrawable );

           // CustomItemizedOverlay destitemizedOverlay = new CustomItemizedOverlay(getDrawable("com/agarwal/route/pin_red.png"));

            OverlayItem destoverlayitem = new OverlayItem(destGeoPoint, "Hello!", "This is dest Location.");

            srcitemizedOverlay.addOverlay(srcoverlayitem);

            destitemizedOverlay.addOverlay(destoverlayitem);

            mapOverlays.add(srcitemizedOverlay);

            mapOverlays.add(destitemizedOverlay);

            connectAsyncTask _connectAsyncTask = new connectAsyncTask();

            _connectAsyncTask.execute();      

            mapView.setBuiltInZoomControls(true);

            mapView.displayZoomControls(true);

            mOverlays = mapView.getOverlays();

            mapView.getController().animateTo(srcGeoPoint);

            mapView.getController().setZoom(12);

        }

    }

    @Override

    protected boolean isRouteDisplayed() {

        // TODO Auto-generated method stub

        return false;

    }

    private class connectAsyncTask extends AsyncTask<Void, Void, Void>{

        private ProgressDialog progressDialog;

        @Override

        protected void onPreExecute() {

            // TODO Auto-generated method stub

            super.onPreExecute();

            progressDialog = new ProgressDialog(_activity);

            progressDialog.setMessage("Fetching route, Please wait...");

            progressDialog.setIndeterminate(true);

            progressDialog.show();

        }

        @Override

        protected Void doInBackground(Void... params) {

            // TODO Auto-generated method stub

            fetchData();

            return null;

        }

        @Override

        protected void onPostExecute(Void result) {

            // TODO Auto-generated method stub

            super.onPostExecute(result);          

            if(doc!=null){

                Overlay ol = new MyOverLay(_activity,srcGeoPoint,srcGeoPoint,1);

                mOverlays.add(ol);

                NodeList _nodelist = doc.getElementsByTagName("status");

                Node node1 = _nodelist.item(0);

                String _status1  = node1.getChildNodes().item(0).getNodeValue();

                if(_status1.equalsIgnoreCase("OK")){

                    NodeList _nodelist_path = doc.getElementsByTagName("overview_polyline");

                    Node node_path = _nodelist_path.item(0);

                    Element _status_path = (Element)node_path;

                    NodeList _nodelist_destination_path = _status_path.getElementsByTagName("points");

                    Node _nodelist_dest = _nodelist_destination_path.item(0);

                    String _path  = _nodelist_dest.getChildNodes().item(0).getNodeValue();

                    List<GeoPoint> _geopoints = decodePoly(_path);

                    GeoPoint gp1;

                    GeoPoint gp2;

                    gp2 = _geopoints.get(0);

                    Log.d("_geopoints","::"+_geopoints.size());

                    for(int i=1;i<_geopoints.size();i++) // the last one would be crash

                    {

                        gp1 = gp2;

                        gp2 = _geopoints.get(i);

                        Overlay ol1 = new MyOverLay(gp1,gp2,2,Color.BLUE);

                        mOverlays.add(ol1);

                    }

                    Overlay ol2 = new MyOverLay(_activity,destGeoPoint,destGeoPoint,3);

                    mOverlays.add(ol2);

                    progressDialog.dismiss();

                }else{

                    showAlert("Unable to find the route");

                }

                Overlay ol2 = new MyOverLay(_activity,destGeoPoint,destGeoPoint,3);

                mOverlays.add(ol2);

                progressDialog.dismiss();

                mapView.scrollBy(-1,-1);

                mapView.scrollBy(1,1);

            }else{

                showAlert("Unable to find the route");

            }

        }

    }

    Document doc = null;

    private void fetchData()

    {

        StringBuilder urlString = new StringBuilder();

        urlString.append("http://maps.google.com/maps/api/directions/xml?origin=");

        urlString.append( Double.toString((double)srcGeoPoint.getLatitudeE6()/1.0E6 ));

        urlString.append(",");

        urlString.append( Double.toString((double)srcGeoPoint.getLongitudeE6()/1.0E6 ));

        urlString.append("&destination=");//to

        urlString.append( Double.toString((double)destGeoPoint.getLatitudeE6()/1.0E6 ));

        urlString.append(",");

        urlString.append( Double.toString((double)destGeoPoint.getLongitudeE6()/1.0E6 ));

        urlString.append("&sensor=true&mode=driving");   

        Log.d("url","::"+urlString.toString());

        HttpURLConnection urlConnection= null;

        URL url = null;

        try

        {

            url = new URL(urlString.toString());

            urlConnection=(HttpURLConnection)url.openConnection();

            urlConnection.setRequestMethod("GET");

            urlConnection.setDoOutput(true);

            urlConnection.setDoInput(true);

            urlConnection.connect();

            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

            DocumentBuilder db = dbf.newDocumentBuilder();

            doc = (Document) db.parse(urlConnection.getInputStream());//Util.XMLfromString(response);

        }catch (MalformedURLException e){

            e.printStackTrace();

        }catch (IOException e){

            e.printStackTrace();

        }catch (ParserConfigurationException e){

            e.printStackTrace();

        }

        catch (SAXException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

    }

    private List<GeoPoint> decodePoly(String encoded) {

        List<GeoPoint> poly = new ArrayList<GeoPoint>();

        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;

            GeoPoint p = new GeoPoint((int) (((double) lat / 1E5) * 1E6),

                    (int) (((double) lng / 1E5) * 1E6));

            poly.add(p);

        }

        return poly;

    }

    private void showAlert(String message){

        AlertDialog.Builder alert = new AlertDialog.Builder(_activity);

        alert.setTitle("Error");

        alert.setCancelable(false);

        alert.setMessage(message);

        alert.setPositiveButton("Ok",new DialogInterface.OnClickListener() {

            @Override

            public void onClick(DialogInterface dialog, int which) {

                // TODO Auto-generated method stub

            }

        });

        alert.show();

    }

    private Drawable getDrawable(String fileName){

        return Drawable.createFromStream(_activity.getClass().getClassLoader().getResourceAsStream(fileName), "pin");

    }

}

Step5

Finally  type following code for your Main Activity class. In Here My One is SharedDataActivity class.

 To generate api key of you, please  follow my blog :-

 http://adrianandroid.blogspot.com/2012/07/android-google-map-tutorial-01loading.html

package com.sha;

import android.app.Activity;

import android.content.Intent;

import android.os.Bundle;

public class SharedDataActivity extends Activity {

    /** Called when the activity is first created. */

 

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.adrian);

       

        SharedData data = SharedData.getInstance();
// to generate api key

        data.setAPIKEY("0yKpGoapYdqNTNFYO-qbnqjzPuGlzK5hyI52Ghw");

        data.setSrc_lat(6.914892);// malbe SLIIT

        data.setSrc_lng(79.973289);

        data.setDest_lat(6.827409);// Bandarawela (Home Town)

        data.setDest_lng(80.985346);

      

        startActivity(new Intent(SharedDataActivity.this,RoutePath.class));

    }

 

}

---------------------------------------------------------------------------------------------------    

 this is  adrian.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="fill_parent"

    android:layout_height="fill_parent"

    android:orientation="vertical" >

   

</LinearLayout>

 --------------------------------------------------------------------------------------------------

Android Manifest 

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.sha"

    android:versionCode="1"

    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="7" />

          <uses-permission android:name="android.permission.INTERNET" />

    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

   

   

   

   

    <application

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name" >

       

        <uses-library android:name="com.google.android.maps" />

       

       

       

        <activity

            android:name=".SharedDataActivity"

            android:label="@string/app_name" >

           

           

           

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

       

        <activity

            android:name="RoutePath"

            android:label="hh" > </activity>

    </application>

</manifest>

----------------------------------------------------------------------------------

 Run your App

 Good Luck!

  Tutorial List 

1. Access C# .net Web service in Android(simple one for Beginners)
2. Android Google Map Tutorial 01(Loading a Google Map)
3. How To Draw Shortest Path Between Two Points in Google Map
4. How to get a longitude & latitude from a given Address