Storing and retrieving locations in SQLite from Google Maps Android API V2

In this article, we will develop an Android application which demonstrates how to store and retrieve Google Maps locations in SQLite database from Google Maps Android API V2.

On taping a location in the Google Map, a marker will be drawn at the taped location and the corresponding coordinates with Google Map zoom level will be saved in SQLite database. On restarting the application, the saved locations are retrieved from the SQLite database and redrawn in the Google Maps.

In this application, the database is accessed via Content Providers. The insertion and deletion operations are executed in non-ui thread using AsyncTask objects and the data retrieval is done using CursorLoader.

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 “LocationMarkerSQLite”

Figure 1 : Create an 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 : Enter MainActivity Details

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. Create a table class in the file src/in/wptrafficanalyzer/locationmarkersqlite/LocationsDB.java

package in.wptrafficanalyzer.locationmarkersqlite;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class LocationsDB extends SQLiteOpenHelper{

    /** Database name */
    private static String DBNAME = "locationmarkersqlite";

    /** Version number of the database */
    private static int VERSION = 1;

    /** Field 1 of the table locations, which is the primary key */
    public static final String FIELD_ROW_ID = "_id";

    /** Field 2 of the table locations, stores the latitude */
    public static final String FIELD_LAT = "lat";

    /** Field 3 of the table locations, stores the longitude*/
    public static final String FIELD_LNG = "lng";

    /** Field 4 of the table locations, stores the zoom level of map*/
    public static final String FIELD_ZOOM = "zom";

    /** A constant, stores the the table name */
    private static final String DATABASE_TABLE = "locations";

    /** An instance variable for SQLiteDatabase */
    private SQLiteDatabase mDB;

    /** Constructor */
    public LocationsDB(Context context) {
        super(context, DBNAME, null, VERSION);
        this.mDB = getWritableDatabase();
    }

    /** This is a callback method, invoked when the method getReadableDatabase() / getWritableDatabase() is called
    * provided the database does not exists
    * */
    @Override
    public void onCreate(SQLiteDatabase db) {
        String sql =     "create table " + DATABASE_TABLE + " ( " +
                         FIELD_ROW_ID + " integer primary key autoincrement , " +
                         FIELD_LNG + " double , " +
                         FIELD_LAT + " double , " +
                         FIELD_ZOOM + " text " +
                         " ) ";

        db.execSQL(sql);
    }

    /** Inserts a new location to the table locations */
    public long insert(ContentValues contentValues){
        long rowID = mDB.insert(DATABASE_TABLE, null, contentValues);
        return rowID;
    }

    /** Deletes all locations from the table */
    public int del(){
        int cnt = mDB.delete(DATABASE_TABLE, null , null);
        return cnt;
    }

    /** Returns all the locations from the table */
    public Cursor getAllLocations(){
        return mDB.query(DATABASE_TABLE, new String[] { FIELD_ROW_ID,  FIELD_LAT , FIELD_LNG, FIELD_ZOOM } , null, null, null, null, null);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    }

}

12. Create content provider class  in the file src/in/wptrafficanalyzer/locationmarkersqlite/LocationsContentProvider.java

package in.wptrafficanalyzer.locationmarkersqlite;

import java.sql.SQLException;

import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.net.Uri;

/** A custom Content Provider to do the database operations */
public class LocationsContentProvider extends ContentProvider{

    public static final String PROVIDER_NAME = "in.wptrafficanalyzer.locationmarkersqlite.locations";

    /** A uri to do operations on locations table. A content provider is identified by its uri */
    public static final Uri CONTENT_URI = Uri.parse("content://" + PROVIDER_NAME + "/locations" );

    /** Constant to identify the requested operation */
    private static final int LOCATIONS = 1;

    private static final UriMatcher uriMatcher ;

    static {
        uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        uriMatcher.addURI(PROVIDER_NAME, "locations", LOCATIONS);
    }

    /** This content provider does the database operations by this object */
    LocationsDB mLocationsDB;

    /** A callback method which is invoked when the content provider is starting up */
    @Override
    public boolean onCreate() {
        mLocationsDB = new LocationsDB(getContext());
        return true;
    }

    /** A callback method which is invoked when insert operation is requested on this content provider */
    @Override
    public Uri insert(Uri uri, ContentValues values) {
        long rowID = mLocationsDB.insert(values);
        Uri _uri=null;
        if(rowID>0){
            _uri = ContentUris.withAppendedId(CONTENT_URI, rowID);
        }else {
            try {
                throw new SQLException("Failed to insert : " + uri);
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return _uri;
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection,
        String[] selectionArgs) {
        // TODO Auto-generated method stub
        return 0;
    }

    /** A callback method which is invoked when delete operation is requested on this content provider */
    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        int cnt = 0;
        cnt = mLocationsDB.del();
        return cnt;
    }

    /** A callback method which is invoked by default content uri */
    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {

        if(uriMatcher.match(uri)==LOCATIONS){
            return mLocationsDB.getAllLocations();
        }
        return null;
    }

    @Override
    public String getType(Uri uri) {
        return null;
    }
}

13. Update the class “MainActivity” in the file src/in/wptrafficanalyzer/locationmarkersqlite/MainActivity.java

package in.wptrafficanalyzer.locationmarkersqlite;

import android.app.Dialog;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.LoaderManager.LoaderCallbacks;
import android.support.v4.content.CursorLoader;
import android.support.v4.content.Loader;
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 implements LoaderCallbacks<Cursor> {

    GoogleMap googleMap;

    @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);

            // Invoke LoaderCallbacks to retrieve and draw already saved locations in map
            getSupportLoaderManager().initLoader(0, null, this);
        }

        googleMap.setOnMapClickListener(new OnMapClickListener() {

            @Override
            public void onMapClick(LatLng point) {

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

                // Creating an instance of ContentValues
                ContentValues contentValues = new ContentValues();

                // Setting latitude in ContentValues
                contentValues.put(LocationsDB.FIELD_LAT, point.latitude );

                // Setting longitude in ContentValues
                contentValues.put(LocationsDB.FIELD_LNG, point.longitude);

                // Setting zoom in ContentValues
                contentValues.put(LocationsDB.FIELD_ZOOM, googleMap.getCameraPosition().zoom);

                // Creating an instance of LocationInsertTask
                LocationInsertTask insertTask = new LocationInsertTask();

                // Storing the latitude, longitude and zoom level to SQLite database
                insertTask.execute(contentValues);

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

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

                // Removing all markers from the Google Map
                googleMap.clear();

                // Creating an instance of LocationDeleteTask
                LocationDeleteTask deleteTask = new LocationDeleteTask();

                // Deleting all the rows from SQLite database table
                deleteTask.execute();

                Toast.makeText(getBaseContext(), "All markers are removed", Toast.LENGTH_LONG).show();
            }
        });
    }

    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);
    }

    private class LocationInsertTask extends AsyncTask<ContentValues, Void, Void>{
        @Override
        protected Void doInBackground(ContentValues... contentValues) {

            /** Setting up values to insert the clicked location into SQLite database */
            getContentResolver().insert(LocationsContentProvider.CONTENT_URI, contentValues[0]);
            return null;
        }
    }

    private class LocationDeleteTask extends AsyncTask<Void, Void, Void>{
        @Override
        protected Void doInBackground(Void... params) {

            /** Deleting all the locations stored in SQLite database */
            getContentResolver().delete(LocationsContentProvider.CONTENT_URI, null, null);
            return null;
        }
    }

    @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;
    }

    @Override
    public Loader<Cursor> onCreateLoader(int arg0,
        Bundle arg1) {

        // Uri to the content provider LocationsContentProvider
        Uri uri = LocationsContentProvider.CONTENT_URI;

        // Fetches all the rows from locations table
        return new CursorLoader(this, uri, null, null, null, null);
    }

    @Override
    public void onLoadFinished(Loader<Cursor> arg0,
        Cursor arg1) {
        int locationCount = 0;
        double lat=0;
        double lng=0;
        float zoom=0;

        // Number of locations available in the SQLite database table
        locationCount = arg1.getCount();

        // Move the current record pointer to the first row of the table
        arg1.moveToFirst();

        for(int i=0;i<locationCount;i++){

            // Get the latitude
            lat = arg1.getDouble(arg1.getColumnIndex(LocationsDB.FIELD_LAT));

            // Get the longitude
            lng = arg1.getDouble(arg1.getColumnIndex(LocationsDB.FIELD_LNG));

            // Get the zoom level
            zoom = arg1.getFloat(arg1.getColumnIndex(LocationsDB.FIELD_ZOOM));

            // Creating an instance of LatLng to plot the location in Google Maps
            LatLng location = new LatLng(lat, lng);

            // Drawing the marker in the Google Maps
            drawMarker(location);

            // Traverse the pointer to the next row
            arg1.moveToNext();
        }

        if(locationCount>0){
            // Moving CameraPosition to last clicked position
            googleMap.moveCamera(CameraUpdateFactory.newLatLng(new LatLng(lat,lng)));

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

    @Override
    public void onLoaderReset(Loader<Cursor> arg0) {
        // TODO Auto-generated method stub
    }
}

14. 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.locationmarkersqlite"
    android:versionCode="1"
    android:versionName="1.0" >

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

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

    <uses-permission android:name="in.wptrafficanalyzer.locationmarkersqlite.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.locationmarkersqlite.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>

        <provider
            android:name="LocationsContentProvider"
            android:authorities="in.wptrafficanalyzer.locationmarkersqlite.locations"
            android:exported="false" />

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

Note : Replace “YOUR_ANDROID_API_KEY” with the Android API key obtained in Step 8.

15. Executing the application

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

Figure 7 : Screenshot of the application in execution

16. Download the source code

Storing and retrieving locations from SQLite in Google Maps Android API V2 - R1 362.85 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
store4js.blogspot.com

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Tags: asynchronous, ASyncTask, CursorLoader, Google Map, Google Map Android API V2, GooglePlayServicesUtil, loader, location, map, marker, MarkerOptions, SupportMapFragment