Android - get current location using google play services

Android location APIs make it easy for you to build location-aware applications, without needing to focus on the details of the underlying location technology. 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

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 

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.
Check following example to have better understanding on how we use AynchTask in any Android application to get work done in the background without interfering main task.

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

Install the Google Play Services SDK

Before you proceed to have location support in your Android Applications, you neet to setup Google Play Services SDK using following simple steps

1. Launch the SDK Manager.
   • From Eclipse (with ADT), select Window > Android SDK Manager. 
   • On Windows, double-click the SDK Manager.exe file at the root of the Android SDK directory.
   • On Mac or Linux, open a terminal and navigate to the tools/ directory in the Android SDK directory, then execute android sdk.

    2. Search for Google Play services option from the given package list under Extra and if its not installed, then install it. The Google Play services SDK is saved in your Android SDK environment at <android-sdk>/extras/google/google_play_services/.

   3. Copy the library project at <android-sdk>/extras/google/google_play_services/libproject/google-play-services_lib/ to the location where you maintain your Android app projects. If you are using Eclipse, import the library project into your workspace. Click File > Import, select Android > Existing Android Code into Workspace, and browse to <android-sdk>/extras/google/google_play_services/libproject/, library project to import it.

Create Android Application:

1		You will use Eclipse IDE to create an Android application and name it as LBSDemo/i> under a package com.example.lbsdemo. While creating this project, make sure you Target SDK and Compile With at the latest version of Android SDK to use higher levels of APIs.
2		Add Google Play Service library in your project by following simple steps given below.
3		Modify src/MainActivity.java file and add required code as shown below to take care of getting current location and its equivalent address.
4		Modify 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.
5		Modify res/values/strings.xml to define required constant values
6		Modify AndroidManifest.xml as shown below
7		Run the application to launch Android emulator and verify the result of the changes done in the aplication.

Let's add Google Play Service reference in the project. Right click on the project and select Build Path > Configure Build Path > Android > and then click Add button which will show google-play-service_lib option to be added, just double click on it, which will add required library reference and you will have window as follows:

 

Following is the content of the modified main activity file src/com.example.lbsdemo/MainActivity.java.

package com.example.lbsdemo;

import java.io.IOException;
import java.util.List;
import java.util.Locale;

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesClient;
import com.google.android.gms.location.LocationClient;

import android.content.Context;
import android.location.Address;
import android.location.Geocoder;
import android.location.Location;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;

import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends FragmentActivity implements
GooglePlayServicesClient.ConnectionCallbacks,
GooglePlayServicesClient.OnConnectionFailedListener
{
   LocationClient mLocationClient;
   private TextView addressLabel;
   private TextView locationLabel;
   private Button getLocationBtn;
   private Button disconnectBtn;
   private Button connectBtn;

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

      locationLabel = (TextView) findViewById(R.id.locationLabel);
      addressLabel = (TextView) findViewById(R.id.addressLabel);
      getLocationBtn = (Button) findViewById(R.id.getLocation);

      getLocationBtn.setOnClickListener(new View.OnClickListener() {
         public void onClick(View view) {
            displayCurrentLocation();
         }
      });
      disconnectBtn = (Button) findViewById(R.id.disconnect);  
      disconnectBtn.setOnClickListener(new View.OnClickListener() {
         public void onClick(View view) {
            mLocationClient.disconnect();
            locationLabel.setText("Got disconnected....");
         }
      });
      connectBtn = (Button) findViewById(R.id.connect);  
      connectBtn.setOnClickListener(new View.OnClickListener() {
         public void onClick(View view) {
            mLocationClient.connect();
            locationLabel.setText("Got connected....");
         }
      }); 
      // Create the LocationRequest object
      mLocationClient = new LocationClient(this, this, this); 
   } 
   @Override
   protected void onStart() {
      super.onStart();
      // Connect the client.
      mLocationClient.connect();
      locationLabel.setText("Got connected....");
   }
   @Override
   protected void onStop() {
      // Disconnect the client.
      mLocationClient.disconnect();
      super.onStop();
      locationLabel.setText("Got disconnected....");
   }
   @Override
   public void onConnected(Bundle dataBundle) {
      // Display the connection status
      Toast.makeText(this, "Connected", Toast.LENGTH_SHORT).show();
   }
   @Override
   public void onDisconnected() {
      // Display the connection status
      Toast.makeText(this, "Disconnected. Please re-connect.",
      Toast.LENGTH_SHORT).show();
   }
   @Override
   public void onConnectionFailed(ConnectionResult connectionResult) {
      // Display the error code on failure
      Toast.makeText(this, "Connection Failure : " + 
      connectionResult.getErrorCode(),
      Toast.LENGTH_SHORT).show();
   }
   public void displayCurrentLocation() {
      // Get the current location's latitude & longitude
      Location currentLocation = mLocationClient.getLastLocation();
      String msg = "Current Location: " +
      Double.toString(currentLocation.getLatitude()) + "," +
      Double.toString(currentLocation.getLongitude());
     
      // Display the current location in the UI
      locationLabel.setText(msg);
      
      // To display the current address in the UI
      (new GetAddressTask(this)).execute(currentLocation);
   }
   /*
    * Following is a subclass of AsyncTask which has been used to get
    * address corresponding to the given latitude & longitude.
    */
   private class GetAddressTask extends AsyncTask<Location, Void, String>{
      Context mContext;
      public GetAddressTask(Context context) {
         super();
         mContext = context;
      }

      /*
       * When the task finishes, onPostExecute() displays the address. 
       */
      @Override
      protected void onPostExecute(String address) {
         // Display the current address in the UI
         addressLabel.setText(address);
      }
      @Override
      protected String doInBackground(Location... params) {
         Geocoder geocoder =
         new Geocoder(mContext, Locale.getDefault());
         // Get the current location from the input parameter list
         Location loc = params[0];
         // Create a list to contain the result address
         List<Address> addresses = null;
         try {
            addresses = geocoder.getFromLocation(loc.getLatitude(),
            loc.getLongitude(), 1);
         } catch (IOException e1) {
            Log.e("LocationSampleActivity", 
            "IO Exception in getFromLocation()");
            e1.printStackTrace();
            return ("IO Exception trying to get address");
         } catch (IllegalArgumentException e2) {
            // Error message to post in the log
            String errorString = "Illegal arguments " +
            Double.toString(loc.getLatitude()) +
            " , " +
            Double.toString(loc.getLongitude()) +
            " passed to address service";
            Log.e("LocationSampleActivity", errorString);
            e2.printStackTrace();
            return errorString;
         }
         // If the reverse geocode returned an address
         if (addresses != null && addresses.size() > 0) {
            // Get the first address
            Address address = addresses.get(0);
            /*
            * Format the first line of address (if available),
            * city, and country name.
            */
            String addressText = String.format(
            "%s, %s, %s",
            // If there's a street address, add it
            address.getMaxAddressLineIndex() > 0 ?
            address.getAddressLine(0) : "",
            // Locality is usually a city
            address.getLocality(),
            // The country of the address
            address.getCountryName());
            // Return the text
            return addressText;
         } else {
            return "No address found";
         }
      }
   }// AsyncTask class
}

Following will be the content of res/layout/activity_main.xml file:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   android:orientation="vertical" >

   <Button android:id="@+id/getLocation"
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:text="@string/get_location"/>

   <Button android:id="@+id/disconnect"
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:text="@string/disconnect"/>
  
   <Button android:id="@+id/connect"
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:text="@string/connect"/>
      
    <TextView
   android:id="@+id/locationLabel"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"/>
    
   <TextView
   android:id="@+id/addressLabel"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"/>
    
</LinearLayout>

Following will be the content of res/values/strings.xml to define two new constants:

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <string name="app_name">LBSDemo</string>
    <string name="action_settings">Settings</string>
    <string name="hello_world">Hello world!</string>
    <string name="get_location">Get Location</string>
    <string name="disconnect">Disconnect Service</string>
    <string name="connect">Connect Service</string>
</resources>

Following is the default content of AndroidManifest.xml:

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

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />
   <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.lbsdemo.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>
    </application>

</manifest>

Let's try to run your LBSDemo application. I assume you have connected your actual Android Mobile device with your computer. To run the app from Eclipse, open one of your project's activity files and click Run icon from the toolbar. Before starting your application, Eclipse will display following window to select an option where you want to run your Android application.

Select mobile device as an option and then check your mobile device which will display following screen:

 Now to see location select Get Location Button which will display location information as follows:

 You can try by disconnecting location client using Disconnect Service and then connecting it by using Connect Service button. You can also modify to get location update as explained above and in Android Official documentation.

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In this android tutorial, i will show you how to highlight the selected item of a ListView, so that it keeps being highlighted. By default, the highlight disppears so in a list-detail page, you don’t see which item has been selected. Other people use a radio to do that, but i prefer to change the background color to lighten the UI. 

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In this tutorial, we show you how to use XML to display a rating bar, few textviews and a button. When user click on the rating bar’s star, the selected rating value will be displayed in the textview. And, if user clicks on the button, the selected rating value will be displayed as a floating message (toast message).

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In Android, you can use Intent.ACTION_SEND to call an existing email client to send an Email.

See following code snippets :

 Intent email = new Intent(Intent.ACTION_SEND);
 email.putExtra(Intent.EXTRA_EMAIL, new String[]{"youremail@yahoo.com"});    
 email.putExtra(Intent.EXTRA_SUBJECT, "subject");
 email.putExtra(Intent.EXTRA_TEXT, "message");
 email.setType("message/rfc822");
 startActivity(Intent.createChooser(email, "Choose an Email client :"));

P.S This project is developed in Eclipse 3.7, and tested with Samsung Galaxy S2 (Android 2.3.3).

Run & test on real device only.
If you run this on emulator, you will hit error message : “No application can perform this action“. This code only work on real device.

1. Android Layout

File : res/layout/main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/linearLayout1"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >
 
    <TextView
        android:id="@+id/textViewPhoneNo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="To : "
        android:textAppearance="?android:attr/textAppearanceLarge" />
 
    <EditText
        android:id="@+id/editTextTo"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:inputType="textEmailAddress" >
 
        <requestFocus />
 
    </EditText>
 
    <TextView
        android:id="@+id/textViewSubject"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Subject : "
        android:textAppearance="?android:attr/textAppearanceLarge" />
 
    <EditText
        android:id="@+id/editTextSubject"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
         >
    </EditText>
 
    <TextView
        android:id="@+id/textViewMessage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Message : "
        android:textAppearance="?android:attr/textAppearanceLarge" />
 
    <EditText
        android:id="@+id/editTextMessage"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="top"
        android:inputType="textMultiLine"
        android:lines="5" />
 
    <Button
        android:id="@+id/buttonSend"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Send" />
 
</LinearLayout>

2. Activity

Full activity class to send an Email. Read the onClick() method, it should be self-explanatory.

package com.mkyong.android;
 
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
 
public class SendEmailActivity extends Activity {
 
 Button buttonSend;
 EditText textTo;
 EditText textSubject;
 EditText textMessage;
 
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
 
  buttonSend = (Button) findViewById(R.id.buttonSend);
  textTo = (EditText) findViewById(R.id.editTextTo);
  textSubject = (EditText) findViewById(R.id.editTextSubject);
  textMessage = (EditText) findViewById(R.id.editTextMessage);
 
  buttonSend.setOnClickListener(new OnClickListener() {
 
   @Override
   public void onClick(View v) {
 
     String to = textTo.getText().toString();
     String subject = textSubject.getText().toString();
     String message = textMessage.getText().toString();
 
     Intent email = new Intent(Intent.ACTION_SEND);
     email.putExtra(Intent.EXTRA_EMAIL, new String[]{ to});
     //email.putExtra(Intent.EXTRA_CC, new String[]{ to});
     //email.putExtra(Intent.EXTRA_BCC, new String[]{to});
     email.putExtra(Intent.EXTRA_SUBJECT, subject);
     email.putExtra(Intent.EXTRA_TEXT, message);
 
     //need this to prompts email client only
     email.setType("message/rfc822");
 
     startActivity(Intent.createChooser(email, "Choose an Email client :"));
 
   }
  });
 }
}

3. Demo

See default scree, fill in the detail, and click on the “send” button.

It will prompts your existing Email client to select.

In this case, i selected Gmail, and all previous filled in detail will be populated to Gmail client automatically.

Note
Android does not provide API to send Email directly, you have to call the existing Email client to send Email.

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In this tutorial, we show you how to turn on/off the phone camera led or flashlight in Android. See code snippets :

1. Turn on

 camera = Camera.open();
 Parameters p = camera.getParameters();
 p.setFlashMode(Parameters.FLASH_MODE_TORCH);
 camera.setParameters(p);
 camera.startPreview();

2. Turn off

 camera = Camera.open();
 Parameters p = camera.getParameters();
 p.setFlashMode(Parameters.FLASH_MODE_OFF);
 camera.setParameters(p);
 camera.stopPreview();

And, put following permission on AndroidManifest.xml.

    <uses-permission android:name="android.permission.CAMERA" />
    <uses-feature android:name="android.hardware.camera" />

P.S This project is developed in Eclipse 3.7, and tested with Samsung Galaxy S2 (Android 2.3.3).

1. Android Layout

A button only.

File : res/layout/main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/relativeLayout1"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >
 
    <Button
        android:id="@+id/buttonFlashlight"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true"
        android:text="Torch" />
 
</RelativeLayout>

2. Activity

Read the code, a button to turn on / off the flashlight, it should be self-explanatory.

package com.mkyong.android;
 
import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.hardware.Camera.Parameters;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
 
public class FlashLightActivity extends Activity {
 
 //flag to detect flash is on or off
 private boolean isLighOn = false;
 
 private Camera camera;
 
 private Button button;
 
 @Override
 protected void onStop() {
  super.onStop();
 
  if (camera != null) {
   camera.release();
  }
 }
 
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
 
  button = (Button) findViewById(R.id.buttonFlashlight);
 
  Context context = this;
  PackageManager pm = context.getPackageManager();
 
  // if device support camera?
  if (!pm.hasSystemFeature(PackageManager.FEATURE_CAMERA)) {
   Log.e("err", "Device has no camera!");
   return;
  }
 
  camera = Camera.open();
  final Parameters p = camera.getParameters();
 
  button.setOnClickListener(new OnClickListener() {
 
   @Override
   public void onClick(View arg0) {
 
    if (isLighOn) {
 
     Log.i("info", "torch is turn off!");
 
     p.setFlashMode(Parameters.FLASH_MODE_OFF);
     camera.setParameters(p);
     camera.stopPreview();
     isLighOn = false;
 
    } else {
 
     Log.i("info", "torch is turn on!");
 
     p.setFlashMode(Parameters.FLASH_MODE_TORCH);
 
     camera.setParameters(p);
     camera.startPreview();
     isLighOn = true;
 
    }
 
   }
  });
 
 }
}

3. Android Permission

Assign CAMERA permission.

File : AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.mkyong.android"
    android:versionCode="1"
    android:versionName="1.0" >
 
    <uses-sdk android:minSdkVersion="10" />
 
    <uses-permission android:name="android.permission.CAMERA" />
    <uses-feature android:name="android.hardware.camera" />
 
    <application
        android:debuggable="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:label="@string/app_name"
            android:name=".FlashLightActivity" >
            <intent-filter >
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
 
</manifest>

4. Demo

None, until i have 2nd hand phone to capture the current flashlight on my phone :)

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