Android Location Fused Provider

This Android tutorial is to explain what a fused location provider is and how to use it to get the location using a sample Android application. We need not explicitly choose either GPS or Network location Provider, as the “Fused Location Provider” automatically chooses the underlying technology and gives the best location as per the need.

In this tutorial we will be using the FusedLocationProviderApi which is the latest API and the best among the available possibilities to get location in Android. If for some reason you wish to use the old APIs then refer the earlier written tutorial to get current location in Android.

Fused Location Provider

• It provides simple and easy to use APIs.
• Provides high accuracy over other options.
• Utilizes low power by choosing the most efficient way to access the location.

Three Use Cases for location access

With respect to fused location provider, we can broadly classify the API usage in three use cases.

1. getLastLocation(GoogleApiClient) this API should be used when there is no need for continuous access to location from an application. Like one shot access or get user location based on some action. This is the simplified way to get the device location and also may not provide high accuracy.
2. requestLocationUpdates(GoogleApiClient,LocationRequest, LocationListener) this API should be used when there a need for continuous location updates and the location is accessed when the application is active in foreground.
3. requestLocationUpdates (GoogleApiClient, LocationRequest, PendingIntent) this API is used to receive location updates in the background even when the application is not active. So the difference is PendingIntent.

Example Android Application to Get Location

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Following is an example Android application that shows how to get the current user location. This also continuously updates the location on the move.

Prerequisite

Google Play Services is required. If you are using Android Studio and Gradle, you should have the following dependencies added in build.gradle file

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:21.0.3'
    compile 'com.google.android.gms:play-services:6.5.87'
}

Note: As of now(14 March 2015), Fused location provider API is not working in all the Android Nexus virtual device emulators. Its a widely reported defect. You can use any other AVD to test in the emulator like WVGA AVDs. I used “4 WVGA API 21” virtual device in emulator to test it. It is also working on a real device and I tested it in Panasonic P81.

AndroidManifest.xml

Remember to give access permissions as shown below. You need not give permission for GPS, Network providers. I have seen Android location access tutorial examples giving all the available permission in the world. Just on android.permission.ACCESS_FINE_LOCATION is enough.

ACCESS_COARSE_LOCATION permission is for approximate location access using cell towers and Wi-Fi. ACCESS_FINE_LOCATION is for precise location access using GPS or cell towers and Wi-Fi. Choose the one that is appropriate for you and do not give both. Battery power is used accordingly.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.javapapers.android.androidlocation" >
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".LocationActivity"
            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.gms.version"
            android:value="@integer/google_play_services_version" />
    </application>

</manifest>

FusedLocationProviderApi Usage

FusedLocationProviderApi

FusedLocationProviderApi can be accessed via LocationServices as below,

    private FusedLocationProviderApi fusedLocationProviderApi = LocationServices.FusedLocationApi;

GoogleApiClient

FusedLocationProviderApi requires the GoogleApiClient instance to get the Location and it can be obtained as below.

	googleApiClient = new GoogleApiClient.Builder(locationActivity)
                .addApi(LocationServices.API)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .build();

• Instantiating the GoogleApiClient should be done in onCreate of the application Activity.
• googleApiClient.connect() should be done in onStart and disconnect() in onStop.
• When the GoogleApiClient is connected successfully, onConnected(Bundle) callback will be called. There we should register with LocationListener for location updates as LocationServices.FusedLocationApi.requestLocationUpdates(
mGoogleApiClient, mLocationRequest, this);

Location Interface Implementations for Callbacks

The following interfaces should be implemented to get the location update.

• LocationListener provides call back for location change through onLocationChanged.
• GoogleApiClient.ConnectionCallbacks provides call back for GoogleApiClient onConnected.
• GoogleApiClient.OnConnectionFailedListener provides call back for GoogleApiClient onConnectionFailed.

Continuous Location Access Activity

Following is the complete class which accesses the Fused Location Provider to get the location continuously in the Android example application.

package com.javapapers.android.androidlocation;

import android.app.Activity;
import android.location.Location;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.common.api.PendingResult;
import com.google.android.gms.common.api.Status;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;

import java.text.DateFormat;
import java.util.Date;

public class LocationActivity extends Activity implements
        LocationListener,
        GoogleApiClient.ConnectionCallbacks,
        GoogleApiClient.OnConnectionFailedListener {

    private static final String TAG = "LocationActivity";
    private static final long INTERVAL = 1000 * 10;
    private static final long FASTEST_INTERVAL = 1000 * 5;
    Button btnFusedLocation;
    TextView tvLocation;
    LocationRequest mLocationRequest;
    GoogleApiClient mGoogleApiClient;
    Location mCurrentLocation;
    String mLastUpdateTime;

    protected void createLocationRequest() {
        mLocationRequest = new LocationRequest();
        mLocationRequest.setInterval(INTERVAL);
        mLocationRequest.setFastestInterval(FASTEST_INTERVAL);
        mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d(TAG, "onCreate ...............................");
        //show error dialog if GoolglePlayServices not available
        if (!isGooglePlayServicesAvailable()) {
            finish();
        }
        createLocationRequest();
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addApi(LocationServices.API)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .build();

        setContentView(R.layout.activity_main);
        tvLocation = (TextView) findViewById(R.id.tvLocation);

        btnFusedLocation = (Button) findViewById(R.id.btnShowLocation);
        btnFusedLocation.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View arg0) {
                updateUI();
            }
        });

    }

    @Override
    public void onStart() {
        super.onStart();
        Log.d(TAG, "onStart fired ..............");
        mGoogleApiClient.connect();
    }

    @Override
    public void onStop() {
        super.onStop();
        Log.d(TAG, "onStop fired ..............");
        mGoogleApiClient.disconnect();
        Log.d(TAG, "isConnected ...............: " + mGoogleApiClient.isConnected());
    }

    private boolean isGooglePlayServicesAvailable() {
        int status = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);
        if (ConnectionResult.SUCCESS == status) {
            return true;
        } else {
            GooglePlayServicesUtil.getErrorDialog(status, this, 0).show();
            return false;
        }
    }

    @Override
    public void onConnected(Bundle bundle) {
        Log.d(TAG, "onConnected - isConnected ...............: " + mGoogleApiClient.isConnected());
        startLocationUpdates();
    }

    protected void startLocationUpdates() {
        PendingResult<Status> pendingResult = LocationServices.FusedLocationApi.requestLocationUpdates(
                mGoogleApiClient, mLocationRequest, this);
        Log.d(TAG, "Location update started ..............: ");
    }

    @Override
    public void onConnectionSuspended(int i) {

    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        Log.d(TAG, "Connection failed: " + connectionResult.toString());
    }

    @Override
    public void onLocationChanged(Location location) {
        Log.d(TAG, "Firing onLocationChanged..............................................");
        mCurrentLocation = location;
        mLastUpdateTime = DateFormat.getTimeInstance().format(new Date());
        updateUI();
    }

    private void updateUI() {
        Log.d(TAG, "UI update initiated .............");
        if (null != mCurrentLocation) {
            String lat = String.valueOf(mCurrentLocation.getLatitude());
            String lng = String.valueOf(mCurrentLocation.getLongitude());
            tvLocation.setText("At Time: " + mLastUpdateTime + "\n" +
                    "Latitude: " + lat + "\n" +
                    "Longitude: " + lng + "\n" +
                    "Accuracy: " + mCurrentLocation.getAccuracy() + "\n" +
                    "Provider: " + mCurrentLocation.getProvider());
        } else {
            Log.d(TAG, "location is null ...............");
        }
    }

    @Override
    protected void onPause() {
        super.onPause();
        stopLocationUpdates();
    }

    protected void stopLocationUpdates() {
        LocationServices.FusedLocationApi.removeLocationUpdates(
                mGoogleApiClient, this);
        Log.d(TAG, "Location update stopped .......................");
    }

    @Override
    public void onResume() {
        super.onResume();
        if (mGoogleApiClient.isConnected()) {
            startLocationUpdates();
            Log.d(TAG, "Location update resumed .....................");
        }
    }
}

Android Layout File

<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"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context=".LocationActivity"
    android:background="#ffffa6c7">

    <TextView
        android:text="@string/locationTxt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/textView"
        android:layout_centerHorizontal="true" />

    <Button
        style="?android:attr/buttonStyleSmall"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Show Location"
        android:id="@+id/btnShowLocation"
        android:layout_toEndOf="@+id/textView"
        android:layout_marginTop="53dp"
        android:layout_below="@+id/textView"
        android:layout_alignParentStart="true"
        android:layout_centerHorizontal="true"
        android:background="#ffff1a7c"
        android:textColor="#ffffffff" />

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tvLocation"
        android:layout_alignParentBottom="true"
        android:layout_marginBottom="134dp"
        android:layout_alignParentEnd="true" />

</RelativeLayout>

Test Run the Location Application via Android Emulator

In Eclipse, Open DDMS perspective (Window -> Open Perspective)

• Select your emulator device
• Select the tab named emulator control
• In ‘Location Controls’ panel, ‘Manual’ tab, give the Longitude and Latitude as input and ‘Send’.

In Android Studio, open Android Device Monitor

The below screen shot will help,

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