How to consume key events

Question

I would like to create a subclass of TextBox that only allows numeric input. My idea was to provide my own onKeyType() handler and consume any key events that do not correspond to digits. However, I can't find any way to consume key events from further processing. How do I do this?
Are there any other suggestions how to accomplish the task of providing your own filter concerning valid key input?
/Bengt

Answer 1

I also wanted a kind of validators for the TextBox class of JavaFX. So I've tried solving the problem using the SwingTextField class and some Java APIs. The following is my code for a SwingTextField accepting only digits, but I do want it to be much simpler.
import java.awt.AWTEvent;
import java.awt.event.AWTEventListener;
import java.awt.event.KeyEvent;
import java.awt.Toolkit;
import javafx.ext.swing.SwingTextField;
import javafx.scene.Scene;
import javafx.stage.Stage;
import javax.swing.JComponent;
class DigitKeyEventHookListener extends AWTEventListener {
    public-init var  source:JComponent;
    public  override function  eventDispatched( event:AWTEvent):Void {
        if (event.getSource().equals(source)) {
            var keyEvent : KeyEvent = event as KeyEvent;
            var keyCharacter = keyEvent.getKeyChar();
            var isDigit = false;
            var code = keyEvent.getKeyCode();
           if ((KeyEvent.VK_0 <= keyCharacter) and (keyCharacter <= KeyEvent.VK_9)) {
                   isDigit = true;
            if ((code ==KeyEvent.VK_DELETE) or (code ==KeyEvent.VK_BACK_SPACE)) {
                isDigit = true;
            if ((code ==KeyEvent.VK_LEFT) or (code ==KeyEvent.VK_RIGHT)) {
                isDigit = true;
           if (not isDigit) {
                keyEvent.consume();
function createSwingTextField() : SwingTextField{
    var field = SwingTextField {
        columns:12
    var listener =  DigitKeyEventHookListener{
        source: field.getJTextField()
    Toolkit.getDefaultToolkit().addAWTEventListener(listener, AWTEvent.KEY_EVENT_MASK);
    return field;
Stage {
    title: "Digit Box"
    width: 200
    height: 80
    scene: Scene {
        content: createSwingTextField()
}