Adding multiple marker locations in Google Maps Android API V2 and save it in Shared Preferences

In this article, we will see how to add multiple marker locations in Google Maps Android API V2 and save it in Shared Preferences.

Since the marker locations are stored in Shared Preferences, the markers can be restored on restarting the application.

This application is developed in Eclipse (4.2.1) with ADT plugin (21.1.0) and Android SDK (21.1.0) and tested in a real Android device (Android 2.3.6  -  GingerBread).

1. Create a new Android application project namely “LocationMarkerPreferences”

Figure 1 : Create new Android Application Project

2. Configure the project

Figure 2 : Configure the application project

3. Design application launcher icon

Figure 3 : Design application launcher icon

4. Create a blank activity

Figure 4 : Create a blank activity

5. Enter MainActivity details

Figure 5 : Create a blank activity

6. Download and configure Google Play Services Library in Eclipse

Google Map for Android is now integrated with Google Play Services. So we need to set up Google Play Service Library for developing Google Map application in Android.

Please follow the given below link to setup Google Play Service library in Eclipse.

http://developer.android.com/google/play-services/setup.html

7. Add Google Play Services Library to this project

Figure 6 : Link Google Play Services Library to this project

8. Get the API key for Google Maps Android API V2

We need to get an API key from Google to use Google Maps in Android application.

Please follow the given below link to get the API key for Google Maps Android API v2.

https://developers.google.com/maps/documentation/android/start

9. Add Android Support library to this project

By default, Android support library (android-support-v4.jar ) is added to this project by Eclipse IDE to the directory libs. If it is not added, we can do it manually by doing the following steps :

• Open Project Explorer by Clicking “Window -> Show View -> Project Explorer”
• Right click this project
• Then from popup menu, Click “Android Tools -> Add Support Library “

10. Update the layout file res/layout/activity_main.xml

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

    <fragment
        android:id="@+id/map"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</RelativeLayout>

11. Update the class “MainActivity” in the file src/in/wptrafficanalyzer/locationmarkerpreferences/MainActivity.java

package in.wptrafficanalyzer.locationmarkerpreferences;

import android.app.Dialog;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.Menu;
import android.widget.Toast;

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.GoogleMap.OnMapClickListener;
import com.google.android.gms.maps.GoogleMap.OnMapLongClickListener;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

public class MainActivity extends FragmentActivity {

    GoogleMap googleMap;
    SharedPreferences sharedPreferences;
    int locationCount = 0;

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

        // Getting Google Play availability status
        int status = GooglePlayServicesUtil.isGooglePlayServicesAvailable(getBaseContext());

        // Showing status
        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

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

            // Getting GoogleMap object from the fragment
            googleMap = fm.getMap();

            // Enabling MyLocation Layer of Google Map
            googleMap.setMyLocationEnabled(true);

            // Opening the sharedPreferences object
            sharedPreferences = getSharedPreferences("location", 0);

            // Getting number of locations already stored
            locationCount = sharedPreferences.getInt("locationCount", 0);

            // Getting stored zoom level if exists else return 0
            String zoom = sharedPreferences.getString("zoom", "0");

            // If locations are already saved
            if(locationCount!=0){

                String lat = "";
                String lng = "";

                // Iterating through all the locations stored
                for(int i=0;i<locationCount;i++){

                    // Getting the latitude of the i-th location
                    lat = sharedPreferences.getString("lat"+i,"0");

                    // Getting the longitude of the i-th location
                    lng = sharedPreferences.getString("lng"+i,"0");

                    // Drawing marker on the map
                    drawMarker(new LatLng(Double.parseDouble(lat), Double.parseDouble(lng)));
                }

                // Moving CameraPosition to last clicked position
                googleMap.moveCamera(CameraUpdateFactory.newLatLng(new LatLng(Double.parseDouble(lat), Double.parseDouble(lng))));

                // Setting the zoom level in the map on last position  is clicked
                googleMap.animateCamera(CameraUpdateFactory.zoomTo(Float.parseFloat(zoom)));
            }
        }

        googleMap.setOnMapClickListener(new OnMapClickListener() {

            @Override
            public void onMapClick(LatLng point) {
                locationCount++;

                // Drawing marker on the map
                drawMarker(point);

                /** Opening the editor object to write data to sharedPreferences */
                SharedPreferences.Editor editor = sharedPreferences.edit();

                // Storing the latitude for the i-th location
                editor.putString("lat"+ Integer.toString((locationCount-1)), Double.toString(point.latitude));

                // Storing the longitude for the i-th location
                editor.putString("lng"+ Integer.toString((locationCount-1)), Double.toString(point.longitude));

                // Storing the count of locations or marker count
                editor.putInt("locationCount", locationCount);

                /** Storing the zoom level to the shared preferences */
                editor.putString("zoom", Float.toString(googleMap.getCameraPosition().zoom));

                /** Saving the values stored in the shared preferences */
                editor.commit();

                Toast.makeText(getBaseContext(), "Marker is added to the Map", Toast.LENGTH_SHORT).show();

            }
        });

        googleMap.setOnMapLongClickListener(new OnMapLongClickListener() {
            @Override
            public void onMapLongClick(LatLng point) {

                // Removing the marker and circle from the Google Map
                googleMap.clear();

                // Opening the editor object to delete data from sharedPreferences
                SharedPreferences.Editor editor = sharedPreferences.edit();

                // Clearing the editor
                editor.clear();

                // Committing the changes
                editor.commit();

                // Setting locationCount to zero
                locationCount=0;

            }
        });
    }

    private void drawMarker(LatLng point){
        // Creating an instance of MarkerOptions
        MarkerOptions markerOptions = new MarkerOptions();

        // Setting latitude and longitude for the marker
        markerOptions.position(point);

        // Adding marker on the Google Map
        googleMap.addMarker(markerOptions);
    }

    @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;
    }
}

12. Update the file AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="in.wptrafficanalyzer.locationmarkerpreferences"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />

    <permission
        android:name="in.wptrafficanalyzer.locationmarkerpreferences.permission.MAPS_RECEIVE"
        android:protectionLevel="signature"/>

    <uses-permission android:name="in.wptrafficanalyzer.locationmarkerpreferences.permission.MAPS_RECEIVE"/>

    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES"/>
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

    <uses-feature
        android:glEsVersion="0x00020000"
        android:required="true"/>

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="in.wptrafficanalyzer.locationmarkerpreferences.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <meta-data
            android:name="com.google.android.maps.v2.API_KEY"
            android:value="YOUR_ANDROID_API_KEY" />

    </application>
</manifest>

13. Executing the application

In Eclipse IDE, we can execute the application from the menu “Run -> Run as -> Android Application”.

Figure 7 : The Android application in action

14. Download the source code

Adding multiple marker locations in Google Maps Android API V2 and save it in Shared Preferences - R1 360.46 KB

Download Full Source Code

How to hire me?

I am George Mathew, working as software architect and Android app developer at wptrafficanalyzer.in

You can hire me on hourly basis or on project basis for Android applications development.

For hiring me, please mail your requirements to info@wptrafficanalyzer.in.

My other blogs
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Tags: Google Map, Google Map Android API V2, GooglePlayServicesUtil, location, map, marker, MarkerOptions, shared preferences, SupportMapFragment