NullPointer Exception on socket.connect() Galaxy Tab 2 running Android 4.04

Question

I seem to be facing this weird error on a socket.connect():

09-18 14:41:22.968: W/System.err(2593): java.lang.NullPointerException
09-18 14:41:22.968: W/Syst         


        

Answer 1

I had the same problem with the Galaxy tab 2 and I solved with:

        BluetoothSocket tmp = null;
        try {
            tmp = device.createRfcommSocketToServiceRecord(SPP_UUID);

            // for others devices its works with:
            // Method m = device.getClass().getMethod("createRfcommSocket", new Class[] {int.class});

            // for galaxy tab 2 with:
            Method m = device.getClass().getMethod("createInsecureRfcommSocket", new Class[] {int.class});

            tmp = (BluetoothSocket) m.invoke(device, 1);
        } catch (IOException e) {
            Log.e(TAG, "failed! error: " + e.getMessage());
        }
        socket = tmp;

        socket.connect();
        Log.i(TAG, "Client Connected!");

Hope this helps =D

Answer 2

Warning: the code below may be insecure, use at your own risk

In my case I was able to connect using createInsecureRfcommSocketToServiceRecord rather than createRfcommSocketToServiceRecord but I see you were already doing that. My code looks more like this (error/exception checking removed):

BluetoothDevice device;
String deviceName = ... selected or hardcoded device name. See Android HDR sample code
BluetoothDevice[] mAllBondedDevices = (BluetoothDevice[]) mBluetoothAdapter.getBondedDevices().toArray(new BluetoothDevice[0]);

for (BluetoothDevice d : mAllBondedDevices) {
  if (deviceName.equals(d.getName())) {
    device = d;
    break;
  }
}

UUID uuid = device.getUuids()[0].getUuid();
//FAILED: socket = device.createRfcommSocketToServiceRecord(uuid);
// Succeeds: Warning, INSECURE!
socket = device.createInsecureRfcommSocketToServiceRecord(uuid);
socket.connect();
this.dos = new DataOutputStream(new BufferedOutputStream(socket.getOutputStream()));
this.dis = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
//etc 

Note that while an insecure connection is not perfect, in our case an insecure connection is preferable to no connection. I posted this an an answer so that you could try the alternate code.