How to fix "lateinit property YYY has not been initialized"

Question

I have a class that makes bluetooth connection and gets a PID from an OBD bluetooth dongle that its connected in the car. But when calling the method for getting RPM then I have an Exception about not initialazing that property.

class BluetoothOBDManager : OBDManager {
    lateinit var context: Context
    private lateinit var input: InputStream
    private lateinit var output: OutputStream
    private lateinit var rpmCommand: RPMCommand
    private lateinit var coolantTempCommand: EngineCoolantTemperatureCommand
    private lateinit var airIntakeTempCommand: AirIntakeTemperatureCommand
    private lateinit var mmSocket : BluetoothSocket

    fun connect(deviceString: String) {
        var adapter: BluetoothAdapter = getDefaultAdapter()
        val device = adapter.getRemoteDevice(deviceString)
        val uuid = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB")
        val mmSocket:BluetoothSocket=device.createRf....Record(uuid)

        mmSocket.let { socket ->
                socket.connect()
            }

        input = mmSocket.inputStream
        output = mmSocket.outputStream
        if (mmSocket.isConnected) {
            println("output.write =1")
            output.write(1)
        }
        rpmCommand = RPMCommand() //This is the INIT of the propert
    }

    override fun getCurrentRpm(): Int {
        rpmCommand.run(input, output) // This line throughs the EXCEPTION
        return rpmCommand.rpm
    }
}

This is how I call the method from another class

BluetoothOBDManager().connect(deviceString)
            var rpm  = BluetoothOBDManager().getCurrentRpm()
            rpmTextView.setText(rpm)

The exception

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: gr.obd.logger, PID: 17486
    kotlin.UninitializedPropertyAccessException: lateinit property rpmCommand has not been initialized

I have tried to INIT the property inside the method but no luck

  override fun getCurrentRpm(): Int {
        rpmCommand = RPMCommand()
        rpmCommand.run(input, output) // This line throughs the EXCEPTION
        return rpmCommand.rpm
    }

Answer 1

BluetoothOBDManager().connect(deviceString)
        var rpm  = BluetoothOBDManager().getCurrentRpm()

Your code creates a BluetoothOBDManager, connects it (initializing rpmCommand), then throws it away, creates a new BluetoothOBDManager with everything uninitialized and tries to call getCurrentRpm on it. It likely should be

val obdManager = BluetoothOBDManager()
obdManager.connect(deviceString)
val rpm = obdManager.getCurrentRpm()

This doesn't explain why you would get

I have tried to INIT the property inside the method but no luck

but that really shouldn't happen; I expect something else is going wrong.