connect to device with Bluetooth address on String

First you will have to findout what profile the bluetooth device supports, For instance it could be a medical device that could use HDP profile or it could be using a simple RS232 over bluetooth. It is important to understand how the bluetooth connection is established for various profiles before you start writing code.

Here is a good link to start with. Android SDK also comes withe some basic examples that you can start with.

http://developer.android.com/guide/topics/connectivity/bluetooth.html

EDIT:

If your device is paired successfully,you will see the MAC address in the list of paired devices. For instance, you can do this to find the device that matches your device's MAC address :

  Set<BluetoothDevice> pairedDevices = mBluetoothAdapter
                    .getBondedDevices();
            if (pairedDevices.isEmpty()) {
                Log.e(TAG,
                        "No devices paired...");
                return ;
            }

    for (BluetoothDevice device : pairedDevices) {
                Log.d(TAG, "Device : address : " + device.getAddress() + " name :"
                        + device.getName());
            if (MY_MAC_ADDR.equals(device.getAddress())) {
                mDevice = device;
                break;
            }
    }

Hope that helps.

Convert the String value to Bluetooth Devices.

BluetoothManager bluetoothManager = (BluetoothManager)getSystemService(Context.BLUETOOTH_SERVICE);
BluetoothDevice mBluetoothDevice = bluetoothManager.getAdapter() .getRemoteDevice("deviceAddress");

If I understand correctly, you have a MAC address as a string, and you want to connect to the device, right? This should work:

BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);
BluetoothSocket tmp = null;
BluetoothSocket mmSocket = null;

// Get a BluetoothSocket for a connection with the
// given BluetoothDevice
try {
    tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
    Method m = device.getClass().getMethod("createRfcommSocket", new Class[] {int.class});
    tmp = (BluetoothSocket) m.invoke(device, 1);
} catch (IOException e) {
    Log.e(TAG, "create() failed", e);
}
mmSocket = tmp;