Using centrifuge-mobile gomobile-generated library from Java (for Android development)

AppMessageHandler.java

package com.example.fz.centrifugoandroid;

import android.app.Activity;
import android.content.Context;
import android.widget.TextView;

import centrifuge.Message;
import centrifuge.MessageHandler;
import centrifuge.Sub;

public class AppMessageHandler implements MessageHandler {
    protected MainActivity context;

    public AppMessageHandler(Context context) {
        this.context = (MainActivity) context;
    }

    @Override
    public void onMessage(Sub sub, final Message message) {
        context.runOnUiThread(new Runnable() {
            @Override
            public void run() {
                TextView tv = (TextView) ((Activity) context).findViewById(R.id.text);
                tv.setText(message.getData());
            }
        });
    }
}

MainActivity.java

package com.example.fz.centrifugoandroid;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;

import centrifuge.Centrifuge;
import centrifuge.Client;
import centrifuge.Credentials;
import centrifuge.EventHandler;
import centrifuge.MessageHandler;
import centrifuge.Sub;
import centrifuge.SubEventHandler;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        TextView tv = (TextView) findViewById(R.id.text);

        Credentials creds = Centrifuge.newCredentials(
                "42", "1488055494", "",
                "24d0aa4d7c679e45e151d268044723d07211c6a9465d0e35ee35303d13c5eeff"
        );

        EventHandler events = Centrifuge.newEventHandler();

        Client client = Centrifuge.new_(
                "ws://192.168.1.33:8000/connection/websocket",
                creds,
                events,
                Centrifuge.defaultConfig()
        );

        try {
            client.connect();
        } catch (Exception e) {
            e.printStackTrace();
            tv.setText(e.getMessage());
            return;
        }
      
        SubEventHandler subEvents = Centrifuge.newSubEventHandler();
        MessageHandler messageHandler = new AppMessageHandler(this);
        subEvents.onMessage(messageHandler);

        try {
            Sub sub = client.subscribe("channel", subEvents);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}