Question

I’m working on app, which uses GPS data. I have an external bluetooth GPS device, but I can’t find how to use the external GPS Bluetooth module. I added the bluetooth permission into my AndroidManifest file, but I dont know how to continue…

Please help.

Answer 1

You should create a connection to the device as described in tutorial Peter pointed.

1. Discover devices and present a list to the user to select one. I assume, you have done this and you now have BluetoothDevice device variable set to your device.

2. Connect as client:

   // This is the default UUID you set for connection - it should work
   private static final UUID DEFAULT_SPP_UUID = UUID
           .fromString("00001101-0000-1000-8000-00805F9B34FB"); 
   
   // ....
   
   BluetoothSocket bluetoothSocket = device
            .createRfcommSocketToServiceRecord(DEFAULT_SPP_UUID);
   
   // ....
   
   bluetoothSocket.connect(); // Do this when you want to start data retrieval
   

3. Retrieve information. You can now open an InputStream, from which NMEA messages come in plain text. So you can use BufferedReader for convenience and read messages line by line.
   Something like this:

   // After successful connect you can open InputStream
   InputStream in = bluetoothSocket.getInputStream();
   InputStreamReader isr = new InputStreamReader(in);
   BufferedReader br = new BufferedReader(isr);
   
   while (true) {
       String nmeaMessage = br.readLine();
       Log.d("NMEA", nmeaMessage);
       // parse NMEA messages
   }
   
   // !!!CLOSE Streams!!!
   

REMEMBER: this code is very simplified. In real application every connection to network, device or filesystem resource should be closed when not needed, errors (Exceptions) properly handled and displayed to user in a readable and understandable format.