DataSource Listener Utility

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Here's a utility class I made to make it easier to create listeners for DataSource changes. Hope it is helpful - and also if you see any issues with this class (or can suggest improvements) would be grateful for any feedback.

package com.kisschedule.app.client;

import com.smartgwt.client.data.Criteria;
import com.smartgwt.client.data.DataSource;
import com.smartgwt.client.data.ResultSet;
import com.smartgwt.client.data.events.DataArrivedEvent;
import com.smartgwt.client.data.events.DataArrivedHandler;
import com.smartgwt.client.data.events.DataChangedEvent;
import com.smartgwt.client.data.events.DataChangedHandler;

public class DataSourceListener implements DataArrivedHandler,
		DataChangedHandler {

	private ResultSet resultSet;
	private DataSourceListenerCallback callback;

	public DataSourceListener(DataSource dataSource,
			DataSourceListenerCallback callback) {
		this(dataSource, callback, null);
	}

	public DataSourceListener(DataSource dataSource,
			DataSourceListenerCallback callback, Criteria criteria) {
		this.callback = callback;
		resultSet = new ResultSet(dataSource);
		if (criteria != null)
			resultSet.setCriteria(criteria);
		resultSet.addDataArrivedHandler(this);
		resultSet.addDataChangedHandler(this);
		resultSet.get(0);
	}

	@Override
	public void onDataChanged(DataChangedEvent event) {
		callback.execute((ResultSet) event.getSource(), null, null);
	}

	@Override
	public void onDataArrived(DataArrivedEvent event) {
		callback.execute((ResultSet) event.getSource(), event.getStartRow(),
				event.getEndRow());
	}

}

and the interface spec

import com.smartgwt.client.data.ResultSet;

public interface DataSourceListenerCallback {
	public void execute(ResultSet resultSet, Integer start, Integer end);
}

Sample usage:

 
 		DataSourceListenerCallback callback = new DataSourceListenerCallback() {
			@Override
			public void execute(ResultSet resultSet, Integer start, Integer end) {
				if (start!=null)
				   updateSettings(resultSet.get(start));
			}
		};

		settingsListener = new DataSourceListener(
				DataSource.get("settings"), callback);

One usage, I haven't tried yet is to update a particular string tag in the UI. For example

 		DataSourceListenerCallback callback = new DataSourceListenerCallback() {
			@Override
			public void execute(ResultSet resultSet, Integer start, Integer end) {
				if (start!=null)
				   updateLabel(resultSet.get(start));
			}
		};

		settingsListener = new DataSourceListener(
				DataSource.get("settings"), callback, new Criteria("setting","labelSetting");

My assumption is that the callback will not fire unless the criteria is matched.

An alternative, and perhaps more general mechanism would be to use GWT Events and instead of a callback, register listeners on those events.