Android Kotlin Cloud HiveMQ example

HiveMQ Cloud
1

Does anyone have an example of how to connect to HiveMQ Cloud (which requires port 8883) from an Android device?

2

Hey msg227,

welcome to the community forums! Are you using HiveMQ’s MQTT Client library?
I am not aware of any Kotlin specific examples.

Kind regards,
Finn

3

I was able to get this to work - I added a ‘connect’ call to my OnCreate in the MainActivity… Here are the stubs for AndroidManifest.xml, build.gradle(Module), and the functions: ‘connect’, ‘publish’,‘subscribe’,‘unsubscribe’,‘disconnect’

The AndroidManifest.xml requires the following permissions and ‘service’ entry:

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.WAKE_LOCK" />
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
 
         <service android:name="org.eclipse.paho.android.service.MqttService" />

The build.gradle (for the module) had a couple of implementations added to the dependencies section:


   implementation 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.2.4'
   implementation 'org.eclipse.paho:org.eclipse.paho.android.service:1.1.1'

fun connect(context: Context) {
        val serverURI = "ssl://{Your Instance}.s1.eu.hivemq.cloud:8883"
        var recCount = 0
        mqttClient = MqttAndroidClient(context, serverURI, "kotlin_client")
        mqttClient.setCallback(object : MqttCallback {
            override fun messageArrived(topic: String?, message: MqttMessage?) {
                recCount = recCount + 1
                Log.d(TAG, "Received message ${recCount}: ${message.toString()} from topic: $topic")
            }

            override fun connectionLost(cause: Throwable?) {
                Log.d(TAG, "Connection lost ${cause.toString()}")
            }

            override fun deliveryComplete(token: IMqttDeliveryToken?) {

            }
        })
        val options = MqttConnectOptions()
        options.userName = "{YOUR USERNAME}"
        options.password = "{YOUR PASSWORD}".toCharArray()
        try {
            mqttClient.connect(options, null, object : IMqttActionListener {
                override fun onSuccess(asyncActionToken: IMqttToken?) {
                    Log.d(TAG, "Connection success")
                    subscribe("{YOUR TOPIC}")
                    publish("{YOUR TOPIC}", "{YOUR MESSAGE}")

                }

                override fun onFailure(asyncActionToken: IMqttToken?, exception: Throwable?) {
                    Log.d(TAG, "Connection failure")
                }
            })
        } catch (e: MqttException) {
            e.printStackTrace()
        }

    }
    fun subscribe(topic: String, qos: Int = 1) {
        try {
            mqttClient.subscribe(topic, qos, null, object : IMqttActionListener {
                override fun onSuccess(asyncActionToken: IMqttToken?) {
                    Log.d(TAG, "Subscribed to $topic")
                }

                override fun onFailure(asyncActionToken: IMqttToken?, exception: Throwable?) {
                    Log.d(TAG, "Failed to subscribe $topic")
                }
            })
        } catch (e: MqttException) {
            e.printStackTrace()
        }
    }

    fun unsubscribe(topic: String) {
        try {
            mqttClient.unsubscribe(topic, null, object : IMqttActionListener {
                override fun onSuccess(asyncActionToken: IMqttToken?) {
                    Log.d(TAG, "Unsubscribed to $topic")
                }

                override fun onFailure(asyncActionToken: IMqttToken?, exception: Throwable?) {
                    Log.d(TAG, "Failed to unsubscribe $topic")
                }
            })
        } catch (e: MqttException) {
            e.printStackTrace()
        }
    }

    fun publish(topic: String, msg: String, qos: Int = 1, retained: Boolean = false) {
        try {
            val message = MqttMessage()
            message.payload = msg.toByteArray()
            message.qos = qos
            message.isRetained = retained
            mqttClient.publish(topic, message, null, object : IMqttActionListener {
                override fun onSuccess(asyncActionToken: IMqttToken?) {
                    Log.d(TAG, "$msg published to $topic")
                }

                override fun onFailure(asyncActionToken: IMqttToken?, exception: Throwable?) {
                    Log.d(TAG, "Failed to publish $msg to $topic")
                }
            })
        } catch (e: MqttException) {
            e.printStackTrace()
        }
    }
    fun disconnect() {
        try {
            mqttClient.disconnect(null, object : IMqttActionListener {
                override fun onSuccess(asyncActionToken: IMqttToken?) {
                    Log.d(TAG, "Disconnected")
                }

                override fun onFailure(asyncActionToken: IMqttToken?, exception: Throwable?) {
                    Log.d(TAG, "Failed to disconnect")
                }
            })
        } catch (e: MqttException) {
            e.printStackTrace()
        }
    }