I finally got the answer, I did that :
private fun CheckBt() {
Toast.makeText(applicationContext, "It has started", Toast.LENGTH_SHORT).show()
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter()
if (!mBluetoothAdapter.enable()) {
Toast.makeText(applicationContext, "Bluetooth Disabled !", Toast.LENGTH_SHORT).show()
/* It tests if the bluetooth is enabled or not, if not the app will show a message. */
finish()
}
if (mBluetoothAdapter == null) {
Toast.makeText(applicationContext, "Bluetooth null !", Toast.LENGTH_SHORT).show()
}
}
fun Connect() {
val device = mBluetoothAdapter.getRemoteDevice("98:D3:32:71:17:DE")
Log.d("", "Connecting to ... $device")
Toast.makeText(applicationContext, "Connecting to ... ${device.name} mac: ${device.uuids[0]} address: ${device.address}", Toast.LENGTH_LONG).show()
mBluetoothAdapter.cancelDiscovery()
try {
btSocket = device.createRfcommSocketToServiceRecord(myUUID)
/* Here is the part the connection is made, by asking the device to create a RfcommSocket (Unsecure socket I guess), It map a port for us or something like that */
btSocket.connect()
Log.d("", "Connection made.")
Toast.makeText(applicationContext, "Connection made.", Toast.LENGTH_SHORT).show()
} catch (e: IOException) {
try {
btSocket.close()
} catch (e2: IOException) {
Log.d("", "Unable to end the connection")
Toast.makeText(applicationContext, "Unable to end the connection", Toast.LENGTH_SHORT).show()
}
Log.d("", "Socket creation failed")
Toast.makeText(applicationContext, "Socket creation failed", Toast.LENGTH_SHORT).show()
}
//beginListenForData()
/* this is a method used to read what the Arduino says for example when you write Serial.print("Hello world.") in your Arduino code */
}
private fun writeData(data: String) {
var outStream = btSocket.outputStream
try {
outStream = btSocket.outputStream
} catch (e: IOException) {
//Log.d(FragmentActivity.TAG, "Bug BEFORE Sending stuff", e)
}
val msgBuffer = data.toByteArray()
try {
outStream.write(msgBuffer)
} catch (e: IOException) {
//Log.d(FragmentActivity.TAG, "Bug while sending stuff", e)
}
}