This becomes possible with the help of Google Play services, which facilitates adding location awareness to your app with automated location tracking, geofencing, and activity recognition.
This tutorial shows you how to use Location Services in your APP to get the current location, get periodic location updates, look up addresses etc.
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The Location Object
The Location object represents a geographic location which can consist of a latitude, longitude, time stamp, and other information such as bearing, altitude and velocity. There are following important methods which you can use with Location object to get location specific information −
Sr.No.Method & Description1 float distanceTo(Location dest)
Returns the approximate distance in meters between this location and the given location.
2 float getAccuracy()
Get the estimated accuracy of this location, in meters.
3 double getAltitude()
Get the altitude if available, in meters above sea level.
4 float getBearing()
Get the bearing, in degrees.
5 double getLatitude()
Get the latitude, in degrees.
6 double getLongitude()
Get the longitude, in degrees.
7 float getSpeed()
Get the speed if it is available, in meters/second over ground.
8 boolean hasAccuracy()
True if this location has an accuracy.
9 boolean hasAltitude()
True if this location has an altitude.
10 boolean hasBearing()
True if this location has a bearing.
11 boolean hasSpeed()
True if this location has a speed.
12 void reset()
Clears the contents of the location.
13 void setAccuracy(float accuracy)
Set the estimated accuracy of this location, meters.
14 void setAltitude(double altitude)
Set the altitude, in meters above sea level.
15 void setBearing(float bearing)
Set the bearing, in degrees.
16 void setLatitude(double latitude)
Set the latitude, in degrees.
17 void setLongitude(double longitude)
Set the longitude, in degrees.
18 void setSpeed(float speed)
Set the speed, in meters/second over ground.
19 String toString()
Returns a string containing a concise, human-readable description of this object.
Get the Current Location
To get the current location, create a location client which is LocationClient object, connect it to Location Services using connect() method, and then call its getLastLocation() method. This method returns the most recent location in the form of Location object that contains latitude and longitude coordinates and other information as explained above. To have location based functionality in your activity, you will have to implement two interfaces −
- GooglePlayServicesClient.ConnectionCallbacks
- GooglePlayServicesClient.OnConnectionFailedListener
These interfaces provide following important callback methods, which you need to implement in your activity class −
Sr.No.Callback Methods & Description1 abstract void onConnected(Bundle connectionHint)
This callback method is called when location service is connected to the location client successfully. You will use connect() method to connect to the location client.
2 abstract void onDisconnected()
This callback method is called when the client is disconnected. You will use disconnect() method to disconnect from the location client.
3 abstract void onConnectionFailed(ConnectionResult result)
This callback method is called when there was an error connecting the client to the service.
You should create the location client in onCreate() method of your activity class, then connect it in onStart(), so that Location Services maintains the current location while your activity is fully visible. You should disconnect the client in onStop() method, so that when your app is not visible, Location Services is not maintaining the current location. This helps in saving battery power up-to a large extent.
Get the Updated Location
If you are willing to have location updates, then apart from above mentioned interfaces, you will need to implement LocationListener interface as well. This interface provide following callback method, which you need to implement in your activity class −
Sr.No.Callback Method & Description1 abstract void onLocationChanged(Location location)
This callback method is used for receiving notifications from the LocationClient when the location has changed.
Location Quality of Service
The LocationRequest object is used to request a quality of service (QoS) for location updates from the LocationClient. There are following useful setter methods which you can use to handle QoS. There are equivalent getter methods available which you can check in Android official documentation.
Sr.No.Method & Description1 setExpirationDuration(long millis)
Set the duration of this request, in milliseconds.
2 setExpirationTime(long millis)
Set the request expiration time, in millisecond since boot.
3 setFastestInterval(long millis)
Explicitly set the fastest interval for location updates, in milliseconds.
4 setInterval(long millis)
Set the desired interval for active location updates, in milliseconds.
5 setNumUpdates(int numUpdates)
Set the number of location updates.
6 setPriority(int priority)
Set the priority of the request.
Now for example, if your application wants high accuracy location it should create a location request with setPriority(int) set to PRIORITY_HIGH_ACCURACY and setInterval(long) to 5 seconds. You can also use bigger interval and/or other priorities like PRIORITY_LOW_POWER for to request "city" level accuracy or PRIORITY_BALANCED_POWER_ACCURACY for "block" level accuracy.
Activities should strongly consider removing all location request when entering the background (for example at onPause()), or at least swap the request to a larger interval and lower quality to save power consumption.
Displaying a Location Address
Once you have Location object, you can use Geocoder.getFromLocation() method to get an address for a given latitude and longitude. This method is synchronous, and may take a long time to do its work, so you should call the method from the doInBackground() method of an AsyncTask class.
The AsyncTask must be subclassed to be used and the subclass will override doInBackground(Params...) method to perform a task in the background and onPostExecute(Result) method is invoked on the UI thread after the background computation finishes and at the time to display the result. There is one more important method available in AyncTask which is execute(Params... params), this method executes the task with the specified parameters.
Example
Following example shows you in practical how to to use Location Services in your app to get the current location and its equivalent addresses etc.
To experiment with this example, you will need actual Mobile device equipped with latest Android OS, otherwise you will have to struggle with emulator which may not work.
Create Android Application
StepDescription1You will use Android studio IDE to create an Android application and name it as Tutorialspoint under a package com.example.tutorialspoint7.myapplication.2add src/GPSTracker.java file and add required code.3Modify src/MainActivity.java file and add required code as shown below to take care of getting current location and its equivalent address.4Modify layout XML file res/layout/activity_main.xml to add all GUI components which include three buttons and two text views to show location/address.5Modify res/values/strings.xml to define required constant values6Modify AndroidManifest.xml as shown below7Run the application to launch Android emulator and verify the result of the changes done in the application. Following is the content of the modified main activity file MainActivity.java.
package com.example.tutorialspoint7.myapplication;import android.Manifest;import android.app.Activity;import android.os.Bundle;import android.support.v4.app.ActivityCompat;import android.test.mock.MockPackageManager;import android.view.View;import android.widget.Button;import android.widget.Toast;publicclassMainActivityextendsActivity{Button btnShowLocation;privatestaticfinalint REQUEST_CODE_PERMISSION =2;String mPermission =Manifest.permission.ACCESS_FINE_LOCATION;// GPSTracker classGPSTracker gps;@Overridepublicvoid onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState); setContentView(R.layout.activity_main);try{if(ActivityCompat.checkSelfPermission(this, mPermission)!=MockPackageManager.PERMISSION_GRANTED){ActivityCompat.requestPermissions(this,newString[]{mPermission}, REQUEST_CODE_PERMISSION);// If any permission above not allowed by user, this condition will execute every time,else your else part will work }}catch(Exception e){ e.printStackTrace();} btnShowLocation =(Button) findViewById(R.id.button);// show location button click event btnShowLocation.setOnClickListener(newView.OnClickListener(){@Overridepublicvoid onClick(View arg0){// create class object gps =newGPSTracker(MainActivity.this);// check if GPS enabledif(gps.canGetLocation()){double latitude = gps.getLatitude();double longitude = gps.getLongitude();// \n is for new lineToast.makeText(getApplicationContext(),"Your Location is - \nLat: "+ latitude +"\nLong: "+ longitude,Toast.LENGTH_LONG).show();}else{// can't get location// GPS or Network is not enabled// Ask user to enable GPS/network in settings gps.showSettingsAlert();}}});}}
Following is the content of the modified main activity file GPSTracker.java.
package com.example.tutorialspoint7.myapplication;import android.app.AlertDialog;import android.app.Service;import android.content.Context;import android.content.DialogInterface;import android.content.Intent;import android.location.Location;import android.location.LocationListener;import android.location.LocationManager;import android.os.Bundle;import android.os.IBinder;import android.provider.Settings;import android.util.Log;publicclassGPSTrackerextendsServiceimplementsLocationListener{privatefinalContext mContext;// flag for GPS statusboolean isGPSEnabled =false;// flag for network statusboolean isNetworkEnabled =false;// flag for GPS statusboolean canGetLocation =false;Location location;// locationdouble latitude;// latitudedouble longitude;// longitude// The minimum distance to change Updates in metersprivatestaticfinallong MIN_DISTANCE_CHANGE_FOR_UPDATES =10;// 10 meters// The minimum time between updates in millisecondsprivatestaticfinallong MIN_TIME_BW_UPDATES =1000*60*1;// 1 minute// Declaring a Location ManagerprotectedLocationManager locationManager;publicGPSTracker(Context context){this.mContext = context; getLocation();}publicLocation getLocation(){try{ locationManager =(LocationManager) mContext.getSystemService(LOCATION_SERVICE);// getting GPS status isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);// getting network status isNetworkEnabled = locationManager .isProviderEnabled(LocationManager.NETWORK_PROVIDER);if(!isGPSEnabled &&!isNetworkEnabled){// no network provider is enabled}else{this.canGetLocation =true;// First get location from Network Providerif(isNetworkEnabled){ locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, MIN_TIME_BW_UPDATES, MIN_DISTANCE_CHANGE_FOR_UPDATES,this);Log.d("Network","Network");if(locationManager !=null){ location = locationManager .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);if(location !=null){ latitude = location.getLatitude(); longitude = location.getLongitude();}}}// if GPS Enabled get lat/long using GPS Servicesif(isGPSEnabled){if(location ==null){ locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, MIN_TIME_BW_UPDATES, MIN_DISTANCE_CHANGE_FOR_UPDATES,this);Log.d("GPS Enabled","GPS Enabled");if(locationManager !=null){ location = locationManager .getLastKnownLocation(LocationManager.GPS_PROVIDER);if(location !=null){ latitude = location.getLatitude(); longitude = location.getLongitude();}}}}}}catch(Exception e){ e.printStackTrace();}return location;}/** * Stop using GPS listener * Calling this function will stop using GPS in your app * */publicvoid stopUsingGPS(){if(locationManager !=null){ locationManager.removeUpdates(GPSTracker.this);}}/** * Function to get latitude * */publicdouble getLatitude(){if(location !=null){ latitude = location.getLatitude();}// return latitudereturn latitude;}/** * Function to get longitude * */publicdouble getLongitude(){if(location !=null){ longitude = location.getLongitude();}// return longitudereturn longitude;}/** * Function to check GPS/wifi enabled * @return boolean * */publicboolean canGetLocation(){returnthis.canGetLocation;}/** * Function to show settings alert dialog * On pressing Settings button will lauch Settings Options * */publicvoid showSettingsAlert(){AlertDialog.Builder alertDialog =newAlertDialog.Builder(mContext);// Setting Dialog Title alertDialog.setTitle("GPS is settings");// Setting Dialog Message alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");// On pressing Settings button alertDialog.setPositiveButton("Settings",newDialogInterface.OnClickListener(){publicvoid onClick(DialogInterface dialog,int which){Intent intent =newIntent(Settings.ACTION_LOCATION_SOURCE_SETTINGS); mContext.startActivity(intent);}});// on pressing cancel button alertDialog.setNegativeButton("Cancel",newDialogInterface.OnClickListener(){publicvoid onClick(DialogInterface dialog,int which){ dialog.cancel();}});// Showing Alert Message alertDialog.show();}@Overridepublicvoid onLocationChanged(Location location){}@Overridepublicvoid onProviderDisabled(String provider){}@Overridepublicvoid onProviderEnabled(String provider){}@Overridepublicvoid onStatusChanged(String provider,int status,Bundle extras){}@OverridepublicIBinder onBind(Intent arg0){returnnull;}}
Following will be the content of res/layout/activity_main.xml file −
<?xml version ="1.0" encoding ="utf-8"?><LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="fill_parent"android:layout_height="fill_parent"android:orientation="vertical"><Buttonandroid:id="@+id/button"android:layout_width="fill_parent"android:layout_height="wrap_content"android:text="getlocation"/></LinearLayout>
Following will be the content of res/values/strings.xml to define two new constants −
<?xml version ="1.0" encoding ="utf-8"?><resources><stringname="app_name">Tutorialspoint</string></resources>
Following is the default content of AndroidManifest.xml −
<?xml version ="1.0" encoding ="utf-8"?><manifestxmlns:android="http://schemas.android.com/apk/res/android"package="com.example.tutorialspoint7.myapplication"><uses-permissionandroid:name="android.permission.ACCESS_FINE_LOCATION"/><uses-permissionandroid:name="android.permission.INTERNET"/><applicationandroid:allowBackup="true"android:icon="@mipmap/ic_launcher"android:label="@string/app_name"android:supportsRtl="true"android:theme="@style/AppTheme"><activityandroid:name=".MainActivity"><intent-filter><actionandroid:name="android.intent.action.MAIN"/><categoryandroid:name="android.intent.category.LAUNCHER"/></intent-filter></activity></application></manifest>
Let's try to run your Tutorialspoint application. I assume that, you have connected your actual Android Mobile device with your computer. To run the app from Android Studio, open one of your project's activity files and click Run
icon from the toolbar. Before starting your application, Android studio installer will display following window to select an option where you want to run your Android application.
Now to see location select Get Location Button which will display location information as follows −
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