button1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            MqttClient client;
            final String BROKER_URL = "tcp://test.mosquitto.org:1883";
            final String TOPIC_NAME = "testtopic1";

            try {
                client = new MqttClient(BROKER_URL, MqttClient.generateClientId(), new MemoryPersistence());


                client.connect();

                MqttTopic myTopic = client.getTopic(TOPIC_NAME);

                int myValue = 75;

                MqttMessage message = new MqttMessage(String.valueOf(myValue).getBytes());

                myTopic.publish(message);

                System.out.println("Submission Successful. Topic: " + myTopic.getName() + "  Message: " + myValue);

                client.disconnect();

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

import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.eclipse.paho.client.mqttv3.MqttTopic;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;