In this part of my Android tutorial I’ll cover many questions brought up after my last Android Google Maps tutorial. This time I’ll cover how to set numerous markers, how to get latitude and longitude data and how to call for a Google Map that shows directions between 2 locations.

I’ll be reusing some of the code from the previous tutorial. All of the new code covered in this video can be found below.

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Code From the Video

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <fragment
        android:layout_width="match_parent"
        android:layout_height="400dp"
        android:id="@+id/map"
        android:name="com.google.android.gms.maps.MapFragment" />

    <EditText
        android:layout_width="215dp"
        android:layout_height="wrap_content"
        android:inputType="textPostalAddress"
        android:ems="10"
        android:id="@+id/addressEditText"
        android:layout_below="@+id/map"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginTop="23dp"
        android:layout_marginRight="10dp"
        android:layout_marginLeft="10dp"
        android:hint="Start Address / Marker" />

    <Button
        android:layout_width="110dp"
        android:layout_height="wrap_content"
        android:text="Marker"
        android:id="@+id/getAddressButton"
        android:layout_alignBottom="@+id/addressEditText"
        android:layout_toRightOf="@+id/addressEditText"
        android:layout_toEndOf="@+id/addressEditText"
        android:layout_marginRight="10dp"
        android:onClick="showAddressMarker"/>

    <EditText
        android:layout_width="215dp"
        android:layout_height="wrap_content"
        android:inputType="textPostalAddress"
        android:ems="10"
        android:id="@+id/finalAddressEditText"
        android:layout_below="@+id/addressEditText"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginTop="23dp"
        android:layout_marginRight="10dp"
        android:layout_marginLeft="10dp"
        android:hint="Destination Address" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Directions"
        android:id="@+id/getDirectionsButton"
        android:layout_alignBottom="@+id/finalAddressEditText"
        android:layout_toRightOf="@+id/finalAddressEditText"
        android:layout_toEndOf="@+id/finalAddressEditText"
        android:layout_marginRight="10dp"
        android:onClick="getDirections"/>

</RelativeLayout>

MainActivity.java

package com.newthinktank.derekbanas.mappy;

import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapFragment;
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 org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;
import java.io.InputStream;

public class MainActivity extends Activity {

    EditText addressEditText, finalAddressEditText;

    // Used to utilize map capabilities
    private GoogleMap googleMap;

    // Stores latitude and longitude data for addresses
    LatLng addressPos, finalAddressPos;

    // Used to place Marker on my map
    Marker addressMarker;

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

        // Initialize my EditTexts
        addressEditText = (EditText) findViewById(R.id.addressEditText);
        finalAddressEditText = (EditText) findViewById(R.id.finalAddressEditText);

        // Initialize my Google Map
        try{

            if(googleMap == null){

                googleMap = ((MapFragment) getFragmentManager().findFragmentById(R.id.map)).getMap();

            }

            googleMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);

            googleMap.setMyLocationEnabled(true);

            googleMap.setTrafficEnabled(true);

            googleMap.setIndoorEnabled(true);

            googleMap.setBuildingsEnabled(true);

            googleMap.getUiSettings().setZoomControlsEnabled(true);

        }
        catch(Exception e){

            e.printStackTrace();

        }

    }

    // Called when getAddressButton is clicked
    public void showAddressMarker(View view) {

        // Get the street address entered
        String newAddress = addressEditText.getText().toString();

        if(newAddress != null){

            // Call for the AsyncTask to place a marker
            new PlaceAMarker().execute(newAddress);

        }

    }

    // Called when getDirectionsButton is clicked
    public void getDirections(View view) {

        // Get the start and ending address
        String startingAddress = addressEditText.getText().toString();
        String finalAddress = finalAddressEditText.getText().toString();

        // Verify that they aren't empty
        if((startingAddress.equals("")) || (finalAddress.equals(""))){

            Toast.makeText(this, "Enter a Starting & Ending Address", Toast.LENGTH_SHORT).show();

        } else {

            // Get the GetDirections AsyncTask to call for the directions
            new GetDirections().execute(startingAddress, finalAddress);

        }

    }

    class PlaceAMarker extends AsyncTask<String, String, String> {

        @Override
        protected String doInBackground(String... params) {

            // Get the 1st address passed
            String startAddress = params[0];

            // Replace the spaces with %20
            startAddress = startAddress.replaceAll(" ","%20");

            // Call for the latitude and longitude and pass in that
            // we don't want directions
            getLatLong(startAddress, false);

            return null;
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);

            // Draw the marker on the screen
            addressMarker = googleMap.addMarker(new MarkerOptions()
                    .position(addressPos)
                    .title("Address"));
        }

    }

    // The AsyncTask that gets directions
    class GetDirections extends AsyncTask<String, String, String> {

        @Override
        protected String doInBackground(String... params) {

            // Get the starting address
            String startAddress = params[0];

            // Replace the spaces with %20
            startAddress = startAddress.replaceAll(" ","%20");

            // Get the lat and long for our address
            getLatLong(startAddress, false);

            // Get the destination address
            String endingAddress = params[1];

            // Replace the spaces with %20
            endingAddress = endingAddress.replaceAll(" ","%20");

            // Get lat and long for the destination address and pass true
            getLatLong(endingAddress, true);

            return null;

        }

        protected void onPostExecute(String s) {
            super.onPostExecute(s);

            // Create the URL for Google Maps to get the directions
            String geoUriString = "http://maps.google.com/maps?saddr=" +
                    addressPos.latitude + "," +
                    addressPos.longitude + "&daddr=" +
                    finalAddressPos.latitude + "," +
                    finalAddressPos.longitude;

            // Call for Google Maps to open
            Intent mapCall = new Intent(Intent.ACTION_VIEW, Uri.parse(geoUriString));

            startActivity(mapCall);

        }

    }

    protected void getLatLong(String address, boolean setDestination){

        // Define the uri that is used to get lat and long for our address
        String uri = "http://maps.google.com/maps/api/geocode/json?address=" +
                address + "&sensor=false";

        // Use the get method to retrieve our data
        HttpGet httpGet = new HttpGet(uri);

        // Acts as the client which executes HTTP requests
        HttpClient client = new DefaultHttpClient();

        // Receives the response from our HTTP request
        HttpResponse response;

        // Will hold the data received
        StringBuilder stringBuilder = new StringBuilder();

        try {

            // Get the response of our query
            response = client.execute(httpGet);

            // Receive the entity information sent with the HTTP message
            HttpEntity entity = response.getEntity();

            // Holds the sent bytes of data
            InputStream stream = entity.getContent();
            int byteData;

            // Continue reading data while available
            while ((byteData = stream.read()) != -1) {
                stringBuilder.append((char) byteData);
            }
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        double lat = 0.0, lng = 0.0;

        // Holds key value mappings
        JSONObject jsonObject;
        try {
            jsonObject = new JSONObject(stringBuilder.toString());

            // Get the returned latitude and longitude
            lng = ((JSONArray)jsonObject.get("results")).getJSONObject(0)
                    .getJSONObject("geometry").getJSONObject("location")
                    .getDouble("lng");

            lat = ((JSONArray)jsonObject.get("results")).getJSONObject(0)
                    .getJSONObject("geometry").getJSONObject("location")
                    .getDouble("lat");

            // Change the lat and long depending on if we want to set the
            // starting or ending destination
            if(setDestination){

                finalAddressPos = new LatLng(lat, lng);

            } else {
                addressPos = new LatLng(lat, lng);
            }

        } catch (JSONException e) {
            e.printStackTrace();
        }

    }

}