Building Arduino Projects for the Internet of Things

CHAPTER 6 ■ IOT PATTERNS: REMOTE CONTROL

Next you are going to write code to communicate with the MQTT broker. As shown in
Figure  6-20 , right-click on the top-level package (in the example, it is com.codifythings.
lightingcontrolsystem ) and choose New ➤ Java Class.

Figure 6-21. Enter new class name

Figure 6-20. Add a new class

Enter MQTTClient in the Name field and click OK, as shown in Figure  6-21.

Android Studio will generate an empty class with the default code shown in Listing 6-8.

Listing 6-8. Default Code for MQTTClient.java

public class MQTTClient
{
...
}

Next you are going to add code to the MQTTClient that will connect and publish
to an MQTT broker whenever the user taps on the app screen. Listing 6-9 provides the
complete implementation of the MQTTClient class.

Listing 6-9. Complete Code of MQTTClient.java

package com.codifythings.lightingcontrolsystem;
import android.util.Log;

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