public class ConnectionListener implements IMqttActionListener {

    private Connection connection;


    public ConnectionListener() {
        // Maybe pass the Listener the client in the constructor?
    }
    @Override
    public void onSuccess(IMqttToken iMqttToken) {

        // Do your publish here using the client

    }

    @Override
    public void onFailure(IMqttToken iMqttToken, Throwable throwable) {

    }
}

final ConnectionListener callback = new ConnectionListener();
client.connect(connectionOptions, userContext, callback);