Android working with Bluetooth

Bluetooth from the IEEE standard 802.15.1 is an open, wireless protocol for exchanging data between devices over short distances.A common example is from a phone to a headset, but other applications can include proximity tracking.To communicate between devices using Bluetooth, four steps need to be performed:
1. Turn on Bluetooth for the device.
2. Find paired or available devices in a valid range.
3. Connect to devices.
4. Transfer data between devices


To use the Bluetooth Service, the application needs to have BLUETOOTH permission to receive and transmit and BLUETOOTH_ADMIN permission to manipulate Bluetooth settings or initiate device discovery.These require the following lines in the AndroidManifest XML file:

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


All the Bluetooth API functionality resides in the android.bluetooth package.There are
five main classes that provide the features:
> BluetoothAdapter—Represents the Bluetooth radio interface that is used to discover devices and instantiate Bluetooth connections
> BluetoothClass—Describes the general characteristics of the Bluetooth device
> BluetoothDevice—Represents a remote Bluetooth device
> BluetoothSocket—Represents the socket or connection point for data exchange with another Bluetooth device
> BluetoothServerSocket—Represents an open socket listening for incoming
requests


Make a project with the name Android BluetoothDemo and have a main activity with name Main.java with the following code




import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;

public class Main extends Activity {
protected static final String TAG = "bluetoothdemo";
int REQUEST_ENABLE_BT = 1;
EditText main;
private ArrayAdapter<String> mNewDevicesArrayAdapter;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        main = (EditText) findViewById(R.id.mainTextArea);
        mNewDevicesArrayAdapter = new ArrayAdapter<String>(this, R.string.app_name);
        
        // Hook up the Discover button to its handler
        Button discover = (Button) findViewById(R.id.discoverButton);
        discover.setOnClickListener(discoverButtonHandler);
        
        // Hook up the ArrayAdapter to the ListView
        ListView lv = (ListView) findViewById(R.id.pairedBtDevices);
        lv.setAdapter(mNewDevicesArrayAdapter);
        
        BluetoothAdapter BT = BluetoothAdapter.getDefaultAdapter();
        if (BT == null) {
        String noDevMsg = "This device does not appear to have a Bluetooth adapter, sorry";
        main.setText(noDevMsg);
        Toast.makeText(this, noDevMsg, Toast.LENGTH_LONG).show();
        return;
        }
        if (!BT.isEnabled()) {
        // Ask user's permission to switch the Bluetooth adapter On. 
        Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(enableIntent, REQUEST_ENABLE_BT);
        } 
    }
        
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode==REQUEST_ENABLE_BT) {
    if (resultCode==Activity.RESULT_OK) {
    BluetoothAdapter BT = BluetoothAdapter.getDefaultAdapter();
    String address = BT.getAddress();
    BT.setName("jitesh");
    String name = BT.getName();
    String connectedMsg = "BT is on; your device is "  + name + " : " + address;
    main.setText(connectedMsg);
    Toast.makeText(this, connectedMsg, Toast.LENGTH_LONG).show();
    Button discoverButton = (Button) findViewById(R.id.discoverButton);
    discoverButton.setOnClickListener(discoverButtonHandler);
    } else {
    Toast.makeText(this, "Failed to enable Bluetooth adapter!", Toast.LENGTH_LONG).show();
    }
    } else {
    Toast.makeText(this, "Unknown RequestCode " + requestCode, Toast.LENGTH_LONG).show();
    }
    }
    
    /** When the user clicks the Discover button, get the list of paired devices
     */
    OnClickListener discoverButtonHandler = new OnClickListener() {

public void onClick(View v) {
Log.d(TAG, "in onClick(" + v + ")");

// IntentFilter for found devices
IntentFilter foundFilter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
// Broadcast receiver for any matching filter
Main.this.registerReceiver(mReceiver, foundFilter);

IntentFilter doneFilter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
Main.this.registerReceiver(mReceiver, doneFilter);
}
};

protected void onDestroy() {
unregisterReceiver(mReceiver);
super.onDestroy();
}
    
/** Receiver for the BlueTooth Discovery Intent; put the paired devices
* into the viewable list.
*/
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {    
@Override
    public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
Log.d(TAG, "in onReceive, action = " + action);
   
    if (BluetoothDevice.ACTION_FOUND.equals(action)){
    BluetoothDevice btDevice = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
   
    if(btDevice.getBondState() != BluetoothDevice.BOND_BONDED){
    // XXX use a better type and a Layout in the visible list
    mNewDevicesArrayAdapter.add(btDevice.getName()+"\n"+btDevice.getAddress());
    }
    }
    else
    if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)){
    setProgressBarIndeterminateVisibility(false);
    setTitle(R.string.select_device);
    if (mNewDevicesArrayAdapter.getCount() == 0){
    String noDevice = getResources().getText(R.string.none_paired).toString();
    mNewDevicesArrayAdapter.add(noDevice);
    }
    }  
    }
    };
}

the main.xml is as follows


<?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"
    >
<EditText
android:id="@+id/mainTextArea"
android:editable="false"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
<ListView 
android:id="@+id/pairedBtDevices"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<Button
android:id="@+id/discoverButton"
android:text="@string/discover"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>

 never foget to add the permissions at manifest filewith the lines

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

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