What to pass in as type handler for Bluetooth class for data transfer?

Question

I am working on an Android app to communicate wirelessly with an Arduino over Bluetooth with an HC-05. I have been following the Transfer Bluetooth data documentation from Android. The following code is what I am using to send and receive data.

    class MyBluetoothService(
        // handler that gets info from Bluetooth service
        private val handler: Handler
    ) {

        private inner class ConnectedThread(private val mmSocket: BluetoothSocket) : Thread() {

            private val mmInStream: InputStream = mmSocket.inputStream
            private val mmOutStream: OutputStream = mmSocket.outputStream
            private val mmBuffer: ByteArray = ByteArray(1024) // mmBuffer store for the stream

            override fun run() {
                var numBytes: Int // bytes returned from read()

                // Keep listening to the InputStream until an exception occurs.
                while (true) {
                    // Read from the InputStream.
                    numBytes = try {
                        mmInStream.read(mmBuffer)
                    } catch (e: IOException) {
                        Log.d(TAG, "Input stream was disconnected", e)
                        break
                    }

                    // Send the obtained bytes to the UI activity.
                    val readMsg = handler.obtainMessage(
                        MESSAGE_READ, numBytes, -1,
                        mmBuffer
                    )
                    readMsg.sendToTarget()
                }
            }

            // Call this from the main activity to send data to the remote device.
            fun write(bytes: ByteArray) {
                try {
                    mmOutStream.write(bytes)
                } catch (e: IOException) {
                    Log.e(TAG, "Error occurred when sending data", e)

                    // Send a failure message back to the activity.
                    val writeErrorMsg = handler.obtainMessage(MESSAGE_TOAST)
                    val bundle = Bundle().apply {
                        putString("toast", "Couldn't send data to the other device")
                    }
                    writeErrorMsg.data = bundle
                    handler.sendMessage(writeErrorMsg)
                    return
                }

                // Share the sent message with the UI activity.
                val writtenMsg = handler.obtainMessage(
                    MESSAGE_WRITE, -1, -1, mmBuffer
                )
                writtenMsg.sendToTarget()
            }

            // Call this method from the main activity to shut down the connection.
            fun cancel() {
                try {
                    mmSocket.close()
                } catch (e: IOException) {
                    Log.e(TAG, "Could not close the connect socket", e)
                }
            }
        }
    }`

When I am creating an instance of MyBluetoothService(Handler) what do I use for the Handler? I want it to constantly be listening for a message from the Arduino.

Answer 1

I was able to figure out the answer to my problem. I ended up defining the value at the top of my code. The code is shown below.

private val handler = Handler(Looper.getMainLooper())

I was able to use this and pass it as the parameter.