Android GPS, Location Manager Tutorial


If you are developing any location based or map application, you can make your app more smarter by finding user’s location automatically. For this you need to integrate GPS modules in your application. In this tutorial i explained how to work with GPS / Location API.

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Adding Permissions in AndroidManifest.xml

Create a new Project in EClipse IDE
1. Create a new project in Eclipse File ⇒ New ⇒ Android Project and fill the required details.

To access GPS in your application you need to add required permissions in AndroidManifest.xml file. If you are getting location using GPS you need to add ACCESS_FINE_LOCATION (Which includes both ACCESS_FINE_LOCATION and ACCESS_COARSE_LOCATION ). Also if you are getting network-based location then you need to add INTERNET permission too.

Open your AndroidManifest.xml file and do the following changes.

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

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

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:name=".AndroidGPSTrackingActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
    
	<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />	
	<uses-permission android:name="android.permission.INTERNET" />

</manifest>


Writing GPS Manager Class

2. Create a new class and name it as GPSTracker.java (I named the class as GPSTracker in this tutorial)
3. Open your GPSTracker.java and change to following. As we need to access system services extend the class from Service

public class GPSTracker extends Service implements LocationListener{

4. Add the required global variables and a constructor for this class.

public class GPSTracker extends Service implements LocationListener {

	private final Context mContext;

	// flag for GPS status
	boolean isGPSEnabled = false;

	// flag for network status
	boolean isNetworkEnabled = false;

	boolean canGetLocation = false;

	Location location; // location
	double latitude; // latitude
	double longitude; // longitude

	// The minimum distance to change Updates in meters
	private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters

	// The minimum time between updates in milliseconds
	private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute

	// Declaring a Location Manager
	protected LocationManager locationManager;

	public GPSTracker(Context context) {
		this.mContext = context;
		getLocation();
	}

5. I am calling geoLocation() function in the constructor. Add a new function called geoLocation() in your GPSTracker class.

public Location 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 Provider
				if (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 Services
				if (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;
	}
	@Override
	public void onLocationChanged(Location location) {
	}

	@Override
	public void onProviderDisabled(String provider) {
	}

	@Override
	public void onProviderEnabled(String provider) {
	}

	@Override
	public void onStatusChanged(String provider, int status, Bundle extras) {
	}

	@Override
	public IBinder onBind(Intent arg0) {
		return null;
	}


Getting user’s current location (Latitude and Longitude)

6. Add the following functions to GPSTracker.java. (These functions will return 0.00 if failed to get latitude and longitude)

/**
	 * Function to get latitude
	 * */
	public double getLatitude(){
		if(location != null){
			latitude = location.getLatitude();
		}
		
		// return latitude
		return latitude;
	}
	
	/**
	 * Function to get longitude
	 * */
	public double getLongitude(){
		if(location != null){
			longitude = location.getLongitude();
		}
		
		// return longitude
		return longitude;
	}


Asking users to Turn On GPS (Launching System Settings)

7. If user turned off the GPS we can use ask user to enable GPS. The following code will show an Alert message asking user to turn on GPS by navigating to GPS Settings automatically.

/**
	 * Function to check if best network provider
	 * @return boolean
	 * */
	public boolean canGetLocation() {
		return this.canGetLocation;
	}
	
	/**
	 * Function to show settings alert dialog
	 * */
	public void showSettingsAlert(){
		AlertDialog.Builder alertDialog = new AlertDialog.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?");
 
        // Setting Icon to Dialog
        //alertDialog.setIcon(R.drawable.delete);
 
        // On pressing Settings button
        alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog,int which) {
            	Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
            	mContext.startActivity(intent);
            }
        });
 
        // on pressing cancel button
        alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
            dialog.cancel();
            }
        });
 
        // Showing Alert Message
        alertDialog.show();
	}
android launching gps settings options
android gps settings options


Stop using GPS

Calling following function will stop using GPS in your application.

/**
	 * Stop using GPS listener
	 * Calling this function will stop using GPS in your app
	 * */
	public void stopUsingGPS(){
		if(locationManager != null){
			locationManager.removeUpdates(GPSTracker.this);
		}		
	}


Final Code (GPSTracker.java)

package com.example.gpstracking;

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;

public class GPSTracker extends Service implements LocationListener {

	private final Context mContext;

	// flag for GPS status
	boolean isGPSEnabled = false;

	// flag for network status
	boolean isNetworkEnabled = false;

	// flag for GPS status
	boolean canGetLocation = false;

	Location location; // location
	double latitude; // latitude
	double longitude; // longitude

	// The minimum distance to change Updates in meters
	private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters

	// The minimum time between updates in milliseconds
	private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute

	// Declaring a Location Manager
	protected LocationManager locationManager;

	public GPSTracker(Context context) {
		this.mContext = context;
		getLocation();
	}

	public Location 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 Provider
				if (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 Services
				if (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
	 * */
	public void stopUsingGPS(){
		if(locationManager != null){
			locationManager.removeUpdates(GPSTracker.this);
		}		
	}
	
	/**
	 * Function to get latitude
	 * */
	public double getLatitude(){
		if(location != null){
			latitude = location.getLatitude();
		}
		
		// return latitude
		return latitude;
	}
	
	/**
	 * Function to get longitude
	 * */
	public double getLongitude(){
		if(location != null){
			longitude = location.getLongitude();
		}
		
		// return longitude
		return longitude;
	}
	
	/**
	 * Function to check GPS/wifi enabled
	 * @return boolean
	 * */
	public boolean canGetLocation() {
		return this.canGetLocation;
	}
	
	/**
	 * Function to show settings alert dialog
	 * On pressing Settings button will lauch Settings Options
	 * */
	public void showSettingsAlert(){
		AlertDialog.Builder alertDialog = new AlertDialog.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", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog,int which) {
            	Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
            	mContext.startActivity(intent);
            }
        });
 
        // on pressing cancel button
        alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
            dialog.cancel();
            }
        });
 
        // Showing Alert Message
        alertDialog.show();
	}

	@Override
	public void onLocationChanged(Location location) {
	}

	@Override
	public void onProviderDisabled(String provider) {
	}

	@Override
	public void onProviderEnabled(String provider) {
	}

	@Override
	public void onStatusChanged(String provider, int status, Bundle extras) {
	}

	@Override
	public IBinder onBind(Intent arg0) {
		return null;
	}

}

Usage:

8. You can get user’s current location by calling simple function from GPSTracker class. Open your main activity and try the following code.

Check gps enabled or not

GPSTracker gps = new GPSTracker(this);
if(gps.canGetLocation()){ // gps enabled} // return boolean true/false

Getting Latitude and Longitude

gps.getLatitude(); // returns latitude
gps.getLongitude(); // returns longitude

Showing GPS Settings Alert Dialog

gps.showSettingsAlert();

Stop using GPS

gps.stopUsingGPS();
package com.example.gpstracking;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class AndroidGPSTrackingActivity extends Activity {
	
	Button btnShowLocation;
	
	// GPSTracker class
	GPSTracker gps;
	
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        btnShowLocation = (Button) findViewById(R.id.btnShowLocation);
        
        // show location button click event
        btnShowLocation.setOnClickListener(new View.OnClickListener() {
			
			@Override
			public void onClick(View arg0) {		
				// create class object
		        gps = new GPSTracker(AndroidGPSTrackingActivity.this);

				// check if GPS enabled		
		        if(gps.canGetLocation()){
		        	
		        	double latitude = gps.getLatitude();
		        	double longitude = gps.getLongitude();
		        	
		        	// \n is for new line
		        	Toast.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();
		        }
				
			}
		});
    }
    
}


Testing your GPS App in Emulator using DDMS Tool

You can test your application in different ways. If you have real device you can directly test the application by installing your application. If you don’t have one, you can test the app using local emulator.

After starting the emulator open DDMS tool form EClipse Windows ⇒ Show Perspective ⇒ DDMS ( Also you can find it on the right corner of IDE)

After opening the DDMS tool you can find list of emulators you opened. Select the appropriate emulator. In Emulator Controls tab you can manually pass your latitude and longitude to emulator.

You can find Emulator testing in demo video of this tutorial.

android gps user location
android gps locator