Programmatically connect to paired Bluetooth device

Okay, since this was driving me crazy, I did some digging into the source code and I've found a 100% reliable (at least on my Nexus 4, Android 4.3) solution to connect to a paired A2DP device (such as a headset or Bluetooth audio device). I've published a fully working sample project (easily built with Android Studio) that you can find here on Github.

Essentially, what you need to do is:

• Get an instance of the BluetoothAdapter
• Using this instance, get a profile proxy for A2DP:

adapter.getProfileProxy (context, listener, BluetoothProfile.A2DP);

where listener is a ServiceListener that will receive a BluetoothProfile in its onServiceConnected() callback (which can be cast to a BluetoothA2dp instance)

• Use reflection to acquire the connect(BluetoothDevice) method on the proxy:

Method connect = BluetoothA2dp.class.getDeclaredMethod("connect", BluetoothDevice.class);

• Find your BluetoothDevice:

String deviceName = "My_Device_Name";BluetoothDevice result = null;Set<BluetoothDevice> devices = adapter.getBondedDevices();if (devices != null) {    for (BluetoothDevice device : devices) {        if (deviceName.equals(device.getName())) {            result = device;            break;        }    }}

• And invoke the connect() method:

connect.invoke(proxy, result);

Which, at least for me, caused an immediate connection of the device.

the best way I found to solve my problem was finding out that I can create a button that brings up the Bluetooth Settings screen. I didn't realize you could do this, or I would have from the beginning.

startActivity(new Intent(Settings.ACTION_BLUETOOTH_SETTINGS));

if the device is already paired , then you can use

if(device.getBondState()==device.BOND_BONDED){        Log.d(TAG,device.getName());        //BluetoothSocket mSocket=null;        try {            mSocket = device.createInsecureRfcommSocketToServiceRecord(MY_UUID);        } catch (IOException e1) {            // TODO Auto-generated catch block            Log.d(TAG,"socket not created");            e1.printStackTrace();        }        try{            mSocket.connect();        }        catch(IOException e){            try {                mSocket.close();                Log.d(TAG,"Cannot connect");            } catch (IOException e1) {                Log.d(TAG,"Socket not closed");                // TODO Auto-generated catch block                e1.printStackTrace();            }        }

for the MY_UUID use

private static final UUID MY_UUID = UUID.fromString("0000110E-0000-1000-8000-00805F9B34FB");

the above code snippet is just to connect your device to an A2DP supported device.I hope it will work.