public class MqttHelper {
        public MqttAndroidClient mqttAndroidClient;

        final String serverUri = "ws://10.3.186.12:9001";

        final String clientId = "ExampleAndroidClient";
        final String subscriptionTopic = "MQTT";

        final String username = "xxxxxxx";
        final String password = "yyyyyyyyyy";

        public MqttHelper(Context context){
            mqttAndroidClient = new MqttAndroidClient(context, serverUri, clientId);
            mqttAndroidClient.setCallback(new 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("MQTT", mqttMessage.toString());
                }

                @Override
                public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {

                }
            });
            connect();
        }

        public void setCallback(MqttCallbackExtended callback) {
            mqttAndroidClient.setCallback(callback);
        }

        private void connect(){
            MqttConnectOptions mqttConnectOptions = new MqttConnectOptions();
            mqttConnectOptions.setAutomaticReconnect(true);
            mqttConnectOptions.setCleanSession(false);
            mqttConnectOptions.setUserName(username);
            mqttConnectOptions.setPassword(password.toCharArray());

            try {

                mqttAndroidClient.connect(mqttConnectOptions, null, new IMqttActionListener() {
                    @Override
                    public void onSuccess(IMqttToken asyncActionToken) {

                        DisconnectedBufferOptions disconnectedBufferOptions = new DisconnectedBufferOptions();
                        disconnectedBufferOptions.setBufferEnabled(true);
                        disconnectedBufferOptions.setBufferSize(100);
                        disconnectedBufferOptions.setPersistBuffer(false);
                        disconnectedBufferOptions.setDeleteOldestMessages(false);
                        mqttAndroidClient.setBufferOpts(disconnectedBufferOptions);
                        subscribeToTopic();
                    }

                    @Override
                    public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
                        Log.w("MQTT", "Failed to connect to: " + serverUri + exception.toString());
                    }
                });


            } catch (MqttException ex){
                ex.printStackTrace();
            }
        }


        private void subscribeToTopic() {
            try {
                mqttAndroidClient.subscribe(subscriptionTopic, 2, null, new IMqttActionListener() {
                    @Override
                    public void onSuccess(IMqttToken asyncActionToken) {
                        Log.w("MQTT","Subscribed!");
                    }

                    @Override
                    public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
                        Log.w("MQTT", "Subscribed fail!");
                    }
                });

            } catch (MqttException ex) {
                System.err.println("Exceptionst subscribing");
                ex.printStackTrace();
            }
        }
    }


    MqttHelper mqttHelper;
    TextView dataReceived;

    @Override

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        dataReceived = (TextView) findViewById(R.id.dataReceived);

        startMqtt();
    }

    private void startMqtt() {
        mqttHelper = new MqttHelper(getApplicationContext());
        mqttHelper.setCallback(new MqttCallbackExtended() {
            @Override
            public void connectComplete(boolean b, String s) {

            }

            @Override
            public void connectionLost(Throwable throwable) {

            }

            @Override
            public void messageArrived(String topic, MqttMessage mqttMessage) throws Exception {
                Log.w("Debug", mqttMessage.toString());
                dataReceived.setText(mqttMessage.toString());
            }

            @Override
            public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {

            }
        });
    }