MQTT Unresolved Reference Android Studio

Question

I have some code I forked off of a website but I could not figure out how to fix this error: "Unresolved Reference: setCallback"

Below is my code:

  fun MqttHelper(context: Context) {
    mqttAndroidClient = MqttAndroidClient(context, serverUri, clientId)
    mqttAndroidClient?.setCallback(object : MqttCallbackExtended {
        override fun connectComplete(b: Boolean, s: String) {
            Log.w("mqtt", s)
        }

        override fun connectionLost(throwable: Throwable) {

        }

        @Throws(Exception::class)
        override fun messageArrived(topic: String, mqttMessage: MqttMessage) {
            Log.w("Mqtt", mqttMessage.toString())
        }

        override fun deliveryComplete(iMqttDeliveryToken: IMqttDeliveryToken) {

        }
    })
    connect()
}

fun setCallback(callback: MqttCallbackExtended) {
    mqttAndroidClient.setCallback(callback)
}


 //in onCreate()
 //This one has the error

 mqttHelper.setCallback(object : MqttCallbackExtended {
        override fun connectComplete(b: Boolean, s: String) {

        }

        override fun connectionLost(throwable: Throwable) {

        }

        @Throws(Exception::class)
        override fun messageArrived(topic: String, mqttMessage: MqttMessage) {
            Log.w("Debug", mqttMessage.toString())
            dataReceived.setText(mqttMessage.toString())
        }

        override fun deliveryComplete(iMqttDeliveryToken: IMqttDeliveryToken) {

        }
    })

If anyone knows how to fix this that would be great, thank you.

Answer 1

You have to create a class, say MqttHelper.kt , like this:

class MqttHelper(context: Context) {

    var mqttAndroidClient: MqttAndroidClient

    init {
        val serverUri = "serverUri"
        val clientId = "client-id"
        mqttAndroidClient = MqttAndroidClient(context, serverUri, clientId)
        mqttAndroidClient.setCallback(object : MqttCallbackExtended {
            override fun connectComplete(b: Boolean, s: String) {
                Log.w("mqtt", s)
            }

            override fun connectionLost(throwable: Throwable) {

            }

            @Throws(Exception::class)
            override fun messageArrived(topic: String, mqttMessage: MqttMessage) {
                Log.w("Mqtt", mqttMessage.toString())
            }

            override fun deliveryComplete(iMqttDeliveryToken: IMqttDeliveryToken) {

            }
        })
        mqttAndroidClient.connect()
    }

    fun setCallback(callback: MqttCallbackExtended) {
        mqttAndroidClient.setCallback(callback)
    }
}

and from within your activity use

var mqttHelper = MqttHelper(this)
mqttHelper.setCallback(...)