MQTT : Android step by step guide using Eclipse Paho

For MQTT integration, recently explored Paho Android project, very simple to use, here are the steps:

Intialize a client, set required options and connect.

    MqttAndroidClient mqttClient = new MqttAndroidClient(BaseApplication.getAppContext(), broker, MQTT_CLIENT_ID);
    //Set call back class
    mqttClient.setCallback(new MqttCallbackHandler(BaseApplication.getAppContext()));
    MqttConnectOptions connOpts = new MqttConnectOptions();
    IMqttToken token = mqttClient.connect(connOpts);

Subscribe to a topic.

    token.setActionCallback(new IMqttActionListener() {
      @Override
      public void onSuccess(IMqttToken arg0) {
           mqttClient.subscribe("TOPIC_NAME" + userId, 2, null, new IMqttActionListener() {
                @Override
                public void onSuccess(IMqttToken asyncActionToken) {
                    Log.d(LOG_TAG, "Successfully subscribed to topic.");
                }

                @Override
                public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
                    Log.d(LOG_TAG, "Failed to subscribed to topic.");
                }
            });
      }
 
      @Override
      public void onFailure(IMqttToken arg0, Throwable arg1) {
           Log.d(LOG_TAG, errorMsg);
      }
    });

Define your callback handler class.

    public class MqttCallbackHandler implements MqttCallbackExtended {
        @Override
            public void connectComplete(boolean b, String s) {
                Log.w("mqtt", s);
            }
 
            @Override
            public void connectionLost(Throwable throwable) {
 
            }
 
            @Override
            public void messageArrived(String topic, MqttMessage mqttMessage) throws Exception {
                Log.w("Anjing", mqttMessage.toString());
            }
 
            @Override
            public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {
 
            }
      }
             
Also set following in manifest file.

    <service android:name="org.eclipse.paho.android.service.MqttService" >
    </service>

Would recommend visiting their project on GitHub and going through samples online.

https://github.com/eclipse/paho.mqtt.android

Hoping this helps.

Cheers !