Question

I’m trying to make a java android application with bluetooth and I have some troubles to show the result after search all the devices paired or not in a listview and to connect to a device, in my code I’m trying to connect with a device using the mac addres of it, but it doesn’t work and I show the result in a textview, any idea????
Thank you.

public class Conexion_bluetooth extends Activity {
TextView out; 

// Debugging
private static final UUID MY_UUID = UUID.fromString("fa87c0d0-afac-11de-8a39-0800200c9a66");
private BluetoothAdapter mBluetoothAdapter = null;
private BluetoothSocket mmSocket=null;
private static final String TAG = "BluetoothChat";
private static final boolean D = true;

private static final int REQUEST_ENABLE_BT = 3;

private BluetoothAdapter mBluetoothAdapter = null;

ListView lstDispositivos;
ListView lstDispositivos2;

@Override
public void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     if(D) Log.e(TAG, "+++ ON CREATE +++");

     // Set up the window layout
     setContentView(R.layout.activity_conexion_bluetooth);

     // Get local Bluetooth adapter
     mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

     // If the adapter is null, then Bluetooth is not supported
     if (mBluetoothAdapter == null) {
         Toast.makeText(this, "Bluetooth is not available", Toast.LENGTH_LONG).show();
         finish();
         return;
     }
 }

@Override
//Comprueba que el bluetooth esta conectado
public void onStart() {
    super.onStart();
    if(D) Log.e(TAG, "++ ON START ++");

    // Si el bluetooth no está activado muestra un mensaje solicitando permiso para activarle
    if (!mBluetoothAdapter.isEnabled()) {
        Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(enableIntent, REQUEST_ENABLE_BT);
        Toast.makeText(this, "conectando...", Toast.LENGTH_LONG).show();

    }else{
        Toast.makeText(this, "conectado", Toast.LENGTH_LONG).show();
    }
}

public void buscar(View view){
    //TextView dispositivos = (TextView) findViewById(R.id.dispositivos);


    if (mBluetoothAdapter.isDiscovering()) {
        Toast.makeText(this, "\nCancel discovery...", Toast.LENGTH_LONG).show();
        mBluetoothAdapter.cancelDiscovery(); 
    }else{
        Toast.makeText(this, "\nStarting discovery...", Toast.LENGTH_LONG).show();
        //mBluetoothAdapter.
        mBluetoothAdapter.startDiscovery(); 
        Toast.makeText(this, "\nDone with discovery...", Toast.LENGTH_LONG).show();
    }

    final TextView dispositivos = (TextView) findViewById(R.id.dispositivos);
    String dispositivo[] = new String[]{};
    final Vector<String> dispositivosBT = new Vector<String>();
    //final int dispEncontrados=0;

    // Create a BroadcastReceiver for ACTION_FOUND
    final BroadcastReceiver mReceiver = new BroadcastReceiver() {
        public void onReceive(Context context, Intent intent) {
            //String dispositivosBT[] = new String[]{};
            String action = intent.getAction();
            // When discovery finds a device
            if (BluetoothDevice.ACTION_FOUND.equals(action)) {
                //setContentView(R.layout.dispositivos_bluetooth);//determinamos que al iniciar la aplicacion aparezca esta pantalla
                    // Get the BluetoothDevice object from the Intent
                BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                    //  Add the name and address to an array adapter to show in a ListView
                    dispositivos.append("\n" + device.getName() + "\n" + device.getAddress());
            }
        }
    };
    // Register the BroadcastReceiver
    IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
    registerReceiver(mReceiver, filter); // Don't forget to unregister during onDestroy

    //dispositivosBT = new String[dispositivos.length()];
    //final ArrayAdapter<String> adaptador = new ArrayAdapter<String>(this, android.R.layout.simple_expandable_list_item_1, dispositivosBT);
    final TextView dispositivosSincronizados = (TextView) findViewById(R.id.dispositivosSincronizados);
    Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
    // If there are paired devices
    if (pairedDevices.size() > 0) {
        // Loop through paired devices
        for (BluetoothDevice device : pairedDevices) {
            // Add the name and address to an array adapter to show in a ListView
            dispositivosSincronizados.append("\n" + device.getName() + "\n" + device.getAddress());
        }
    }
}
public void paraBusqueda(View view){
    if (mBluetoothAdapter.isDiscovering()) {
        Toast.makeText(this, "\nCancel discovery...", Toast.LENGTH_LONG).show();
        mBluetoothAdapter.cancelDiscovery();
    }else{
        Toast.makeText(this, "\nis not discovering...", Toast.LENGTH_LONG).show();
    }

}

public void pararBluetooth(){
    if (mBluetoothAdapter.isEnabled()) {
        Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(enableIntent, REQUEST_ENABLE_BT);        
    }
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_conexion_bluetooth, menu);
    return true;
}

public void conectar(View view){
    String address = "00:15:83:07:d1:14";
 device = mBluetoothAdapter.getRemoteDevice(address);
 Toast.makeText(getApplicationContext(), "cONNECTING", Toast.LENGTH_SHORT).show();
 try {

 mmSocket = device.createRfcommSocketToServiceRecord(MY_UUID);
 mmSocket.connect();
 } catch (IOException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 }
}

}

Answer 1

Using AsyncTask we can make Bluetooth Connection.

 public class BluetoothConnectionActivity extends Activity {

    private Button connectButton;

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

            connectButton = (Button) findViewById(R.id.connectButton);
            connectButton.setOnclickListener(View.onClickListener() {
                        @Override
                    public void onClick(View v) {
                           String address = "00:15:83:07:d1:14";
                   new ConnectAsyncTask(address).execute();
                    }
                    });


        }

    private class ConnectAsyncTask extends AsyncTask<String, Void, Boolean> {
        @Override
        protected void onPostExecute(Boolean isConnected) {
            Toast.makeText(getApplicationContext(), "Connecting...",
                    Toast.LENGTH_SHORT).show();
        }

        @Override
        protected Boolean doInBackground(String... param) {
            BluetoothDevice device = BluetoothAdapter
                    .getDefaultBluetoothAdapter().getRemoteDevice(param[0]);
            try {
                BluetoothSocket mmSocket = device
                        .createRfcommSocketToServiceRecord(MY_UUID);
                mmSocket.connect();
            } catch (Exception e) {
                e.printStackTrace();
                Log.d("BluetoothConnectivity", "ERROR:" + e.getMessage());
                return false;
            }
            return true;
        }

        @Override
        protected void onPostExecute(Boolean isConnected) {
            if (isConnected) {
                Toast.makeText(getApplicationContext(), "Connected",
                        Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(getApplicationContext(), "Failed to connected",
                        Toast.LENGTH_SHORT).show();
            }
        }
    }
}

Regards
Srini