Friday, August 23, 2013

Android Fundamentals

From a developer's perspective, the fundamental building blocks / components of Android are:
1. Activities
2. Services
3. Broadcast Receivers
4. Content Providers.


The means of communication between the above mentioned components is through
1. Intents
2. Intent Filters


The User Interface elements are by using what are called:
1. Views
2. Notifications


Now, having broadly classified the basics, I would like to give a simple definition for each of them, before we can appreciate the need for each of them.


Activity is the basic building block of every visible android application. It provides the means to render a UI. Every screen in an application is an activity by itself. Though they work together to present an application sequence, each activity is an independent entity.


Service is another building block of android applications which does not provide a UI. It is a program that can run in the background for an indefinite period.


Broadcast Receiver is yet another type of component that can receive and respond to any broadcast announcements.


Content Providers are a separate league of components that expose a specific set of data to applications.


While the understanding and knowledge of these four components is good enough to start development, the knowledge of the means of communication between the components is also essential. The platform designers have introduced a new conpect of communication through intents and intent filters.


Intents are messages that are passed between components. So, is it equivalent to parameters passed to API calls? Yes, it is close to that. However, the fundamental differences between API calls and intents' way of invoking components is

1. API calls are synchronous while intent-based invocation is asynchronous (mostly)
2. API calls are bound at compile time while intent-based calls are run-time bound (mostly)


It is these two differences that take Android platform to a different league.


NOTE: Intents can be made to work exactly like API calls by using what are called explicit intents, which will be explained later. But more often than not, implicit intents are the way to go and that is what is explained here.



One component that wants to invoke another has to only express its' "intent" to do a job. And any other component that exists and has claimed that it can do such a job through "intent-filters", is invoked by the android platform to accomplish the job. This means, both the components are not aware of each other's existence and can still work together to give the desired result for the end-user.


This dotted line connection between components is achieved through the combination of intents, intent-filters and the android platform.


This leads to huge possibilities like:

1. Mix and match or rather plug and play of components at runtime
2. Replacing the inbuilt android applications with custom developed applications
3. Component level reuse within and across applications
4. Service orientation to the most granular level, if I may say


Now that the concept of intent has been introduced, let me get down to a more formal definition of Intent.


Intent is a bundle of information, a passive data structure that holds an abstract description of the operation to be performed. (or in the case of broadcasts, a description of an event that has happened and is being announced).


There are 2 types of intents which I intend to detail in the next part of this series. Before winding up part 1, I would finally also give you a formal definition of Intent filters.


Intent filters are the means through which a component advertizes its own capabilities to handle specific job/operations to the android platform.

Wednesday, May 22, 2013

Detect Battery Info.

The app simple detect battery level, voltage, temperature, technology, charging status, and health of the battery.



Activity


 public class MainActivity extends Activity {

    private TextView batteryLevel, batteryVoltage, batteryTemperature,
            batteryTechnology, batteryStatus, batteryHealth;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        batteryLevel = (TextView) findViewById(R.id.batterylevel);
        batteryVoltage = (TextView) findViewById(R.id.batteryvoltage);
        batteryTemperature = (TextView) findViewById(R.id.batterytemperature);
        batteryTechnology = (TextView) findViewById(R.id.batterytechology);
        batteryStatus = (TextView) findViewById(R.id.batterystatus);
        batteryHealth = (TextView) findViewById(R.id.batteryhealth);

        this.registerReceiver(this.myBatteryReceiver, new IntentFilter(
                Intent.ACTION_BATTERY_CHANGED));
    }

    private BroadcastReceiver myBatteryReceiver = new BroadcastReceiver() {

        @Override
        public void onReceive(Context arg0, Intent arg1) {
            // TODO Auto-generated method stub

            if (arg1.getAction().equals(Intent.ACTION_BATTERY_CHANGED)) {
                batteryLevel.setText("Level: "
                        + String.valueOf(arg1.getIntExtra("level", 0)) + "%");
                batteryVoltage
                        .setText("Voltage: "
                                + String.valueOf((float) arg1.getIntExtra(
                                        "voltage", 0) / 1000) + "V");
                batteryTemperature.setText("Temperature: "
                        + String.valueOf((float) arg1.getIntExtra(
                                "temperature", 0) / 10) + "c");
                batteryTechnology.setText("Technology: "
                        + arg1.getStringExtra("technology"));

                int status = arg1.getIntExtra("status",
                        BatteryManager.BATTERY_STATUS_UNKNOWN);
                String strStatus;
                if (status == BatteryManager.BATTERY_STATUS_CHARGING) {
                    strStatus = "Charging";
                } else if (status == BatteryManager.BATTERY_STATUS_DISCHARGING) {
                    strStatus = "Dis-charging";
                } else if (status == BatteryManager.BATTERY_STATUS_NOT_CHARGING) {
                    strStatus = "Not charging";
                } else if (status == BatteryManager.BATTERY_STATUS_FULL) {
                    strStatus = "Full";
                } else {
                    strStatus = "Unknown";
                }
                batteryStatus.setText("Status: " + strStatus);

                int health = arg1.getIntExtra("health",
                        BatteryManager.BATTERY_HEALTH_UNKNOWN);
                String strHealth;
                if (health == BatteryManager.BATTERY_HEALTH_GOOD) {
                    strHealth = "Good";
                } else if (health == BatteryManager.BATTERY_HEALTH_OVERHEAT) {
                    strHealth = "Over Heat";
                } else if (health == BatteryManager.BATTERY_HEALTH_DEAD) {
                    strHealth = "Dead";
                } else if (health == BatteryManager.BATTERY_HEALTH_OVER_VOLTAGE) {
                    strHealth = "Over Voltage";
                } else if (health == BatteryManager.BATTERY_HEALTH_UNSPECIFIED_FAILURE) {
                    strHealth = "Unspecified Failure";
                } else {
                    strHealth = "Unknown";
                }
                batteryHealth.setText("Health: " + strHealth);

            }
        }

    };
}

XML activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView 
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="hello"
    />
<TextView 
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Battery Info."
    />
<TextView 
    android:id="@+id/batterylevel"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Battery Level:"
    />
<TextView 
    android:id="@+id/batteryvoltage"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Battery Voltage:"
    />
<TextView 
    android:id="@+id/batterytemperature"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Battery Temperature:"
    />
<TextView 
    android:id="@+id/batterytechology"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Technology:"
    />
<TextView 
    android:id="@+id/batterystatus"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Status:"
    />
<TextView 
    android:id="@+id/batteryhealth"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Health:"
    />
</LinearLayout>



Tuesday, May 21, 2013

Android Enable GPS (Check and prompt user to enable GPS)

To check if the GPS have been enabled or not, the following code can be used:

String provider = Settings.Secure.getString(getContentResolver(), Settings.Secure.LOCATION_PROVIDERS_ALLOWED);

If it's empty, means the GPS have not been enabled. You can start activity with intentSettings.ACTION_SECURITY_SETTINGS, to switch to GPS setting page.




Activity

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.provider.Settings;
import android.widget.Toast;

public class AndroidEnableGPS extends Activity {
   /** Called when the activity is first created. */
   @Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.main);
     
       CheckEnableGPS();
   }
 
   private void CheckEnableGPS(){
    String provider = Settings.Secure.getString(getContentResolver(),
      Settings.Secure.LOCATION_PROVIDERS_ALLOWED);
       if(!provider.equals("")){
           //GPS Enabled
        Toast.makeText(AndroidEnableGPS.this, "GPS Enabled: " + provider,
          Toast.LENGTH_LONG).show();
       }else{
        Intent intent = new Intent(Settings.ACTION_SECURITY_SETTINGS);
           startActivity(intent);
       }

   }
}


Android Location New Features

Sunday, April 7, 2013

Android Notifications

Android allows to put notification into the titlebar of your application. The user can expand the notification bar and by selecting the notification the user can trigger another activity.

Notifications in Android are represented by the Notification class.

The Notification.Builderhttp://developer.android.com/reference/android/app/Notification.Builder.html provides an builder interface to create an Notification object.

Activity-MainActivity.java 
 
  private static final int MY_NOTIFICATION_ID = 1;
   private NotificationManager notificationManager;
    private Notification myNotification;
    private final String myBlog = "http://niravranpara.blogspot.com/"; 


    buttonSend.setOnClickListener(new Button.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
                myNotification = new Notification(R.drawable.ic_launcher,
                        "Notification!", System.currentTimeMillis());
                Context context = getApplicationContext();
                String notificationTitle = "Exercise of Notification!";
                String notificationText = "http://niravranpara.blogspot.com/";
                Intent myIntent = new Intent(Intent.ACTION_VIEW, Uri
                        .parse(myBlog));
                PendingIntent pendingIntent = PendingIntent.getActivity(
                        MainActivity.this, 0, myIntent,
                        Intent.FLAG_ACTIVITY_NEW_TASK);
                myNotification.defaults |= Notification.DEFAULT_SOUND;
                myNotification.flags |= Notification.FLAG_AUTO_CANCEL;
                myNotification.setLatestEventInfo(context, notificationTitle,
                        notificationText, pendingIntent);
                notificationManager.notify(MY_NOTIFICATION_ID, myNotification);

        }
        });



<uses-permission android:name="android.permission.VIBRATE"/>



 

Tuesday, April 2, 2013

Android get current GPS location

You can Find location either GPS_PROVIDER or NETWORK_PROVIDER
Overview of location services in Android , LocationManager class at the heart of location services in Android.
Here is one example which try to find location using GPS , if your GPS not available then try to use network for find location

Demo Code

Activity - AndroidGPSTrackingActivity.java

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();
                }
              
            }
        });
    }
  
}


GPSTracke.java
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;
                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;
    }

}
Layout - main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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/btnShowLocation"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Show Location"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true"/>

</RelativeLayout>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />  
    <uses-permission android:name="android.permission.INTERNET" />


Sunday, March 31, 2013

Android Internal and External storage

  • Android Internal Storage
    •  Internal storage are private to your application and other applications cannot access them (nor can the user).
    •  When the user uninstalls your application, these files are removed.
  •  Android External Storage
    •  External storage such as SD card can also store application data.
    •  There's no security enforced upon files you save to the external storage.
    •  All applications can read and write files placed on the external storage and the user can remove them.
    •  You need Read and Write permission in External Storage
In this example we are going to save data from an EditText to both Internal Storage and External Storage, and then try to get the data back from the respective storage places.

 FileOutputStream :For save Data
 FileInputStream  :For Display data



Layout - activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Storage Demo" />

    <EditText
        android:id="@+id/InputText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:gravity="top|left"
        android:inputType="textMultiLine"
        android:lines="5"
        android:minLines="2"
        android:text="Internal and External Storage" >

        <requestFocus />
    </EditText>

    <Button
        android:id="@+id/InternalStorageSave"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Internal Storage(Save)" />

    <Button
        android:id="@+id/InternalStorageGet"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Internal Storage(Display)" />

    <Button
        android:id="@+id/ExternalStorageSave"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="External Storage(Save)" />

    <Button
        android:id="@+id/ExternalStorageGet"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="External Storage(Displays)" />

    <TextView
        android:id="@+id/responseText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="5dp"
        android:text=""
        android:textAppearance="?android:attr/textAppearanceMedium" />

</LinearLayout>

Activity - MainActivity.java

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;

import android.app.Activity;
import android.content.Context;
import android.content.ContextWrapper;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;



public class MainActivity extends Activity implements OnClickListener {

    private String filename = "StorageFile.txt";
    private String filepath = "FileStorage";
    File myInternalFile;
    File myExternalFile;

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

        ContextWrapper contextWrapper = new ContextWrapper(
                getApplicationContext());
        File directory = contextWrapper.getDir(filepath, Context.MODE_PRIVATE);
        myInternalFile = new File(directory, filename);

        Button saveToInternalStorage = (Button) findViewById(R.id.InternalStorageSave);
        saveToInternalStorage.setOnClickListener(this);

        Button readFromInternalStorage = (Button) findViewById(R.id.InternalStorageGet);
        readFromInternalStorage.setOnClickListener(this);

        Button saveToExternalStorage = (Button) findViewById(R.id.ExternalStorageSave);
        saveToExternalStorage.setOnClickListener(this);

        Button readFromExternalStorage = (Button) findViewById(R.id.ExternalStorageGet);
        readFromExternalStorage.setOnClickListener(this);

        // check if external storage is available and not read only
        if (!isExternalStorageAvailable() || isExternalStorageReadOnly()) {
            saveToExternalStorage.setEnabled(false);
        } else {
            myExternalFile = new File(getExternalFilesDir(filepath), filename);
        }

    }

    public void onClick(View v) {

        EditText myInputText = (EditText) findViewById(R.id.InputText);
        TextView responseText = (TextView) findViewById(R.id.responseText);
        String myData = "";

        switch (v.getId()) {
        case R.id.InternalStorageSave:
            try {
                FileOutputStream fos = new FileOutputStream(myInternalFile); // save
                fos.write(myInputText.getText().toString().getBytes());
                fos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            myInputText.setText("");
            responseText.setText("Saved to Internal Storage.(StorageFile.txt)");
            break;

        case R.id.InternalStorageGet:
            try {
                FileInputStream fis = new FileInputStream(myInternalFile); // display
                DataInputStream in = new DataInputStream(fis);
                BufferedReader br = new BufferedReader(
                        new InputStreamReader(in));
                String strLine;
                while ((strLine = br.readLine()) != null) {
                    myData = myData + strLine;
                }
                in.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            myInputText.setText(myData);
            responseText
                    .setText("Data retrieved from Internal Storage.(StorageFile.txt)");

            break;

        case R.id.ExternalStorageSave:
            try {
                FileOutputStream fos = new FileOutputStream(myExternalFile);
                fos.write(myInputText.getText().toString().getBytes());
                fos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            myInputText.setText("");
            responseText.setText("Saved to External Storage.(StorageFile.txt)");
            break;

        case R.id.ExternalStorageGet:
            try {
                FileInputStream fis = new FileInputStream(myExternalFile);
                DataInputStream in = new DataInputStream(fis);
                BufferedReader br = new BufferedReader(
                        new InputStreamReader(in));
                String strLine;
                while ((strLine = br.readLine()) != null) {
                    myData = myData + strLine;
                }
                in.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            myInputText.setText(myData);
            responseText
                    .setText("Data retrieved from Internal Storage.(StorageFile.txt)");
            break;

        }
    }

    private static boolean isExternalStorageReadOnly() {
        String extStorageState = Environment.getExternalStorageState();
        if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(extStorageState)) {
            return true;
        }
        return false;
    }

    private static boolean isExternalStorageAvailable() {
        String extStorageState = Environment.getExternalStorageState();
        if (Environment.MEDIA_MOUNTED.equals(extStorageState)) {
            return true;
        }
        return false;
    }

}

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>