Trying to make up a Modal Dialog with customized event dispatcher

Question

Hello everyone.
I try to make up a ModalDialog class with customized event dispatcher in order to wait an invoker.
But it fails :-(
import javafx.event.ActionEvent;
import javafx.event.Event;
import javafx.event.EventDispatchChain;
import javafx.event.EventHandler;
import javafx.event.EventTarget;
import javafx.event.EventType;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.stage.Modality;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
import javafx.stage.Window;
import javafx.stage.WindowEvent;
import com.sun.javafx.stage.WindowEventDispatcher;
import java.util.ArrayList;
public class ModalDialog extends Stage {
  ArrayList<Button> buttons;
  int rc;
  Stage stage;
  Event event;
  EventDispatchChain tail;
  public ModalDialog( Window owner, String title ){
    initModality( Modality.APPLICATION_MODAL );
    initOwner( owner );
    initStyle( StageStyle.UTILITY );
    setTitle( title );
    stage = this;
  public void setContents( Group group, ArrayList<Button> buttons ){
    BorderPane root = new BorderPane();
    Scene scene = new Scene(root);
    setScene(scene);
    root.setCenter( group );
    this.buttons = buttons;
    HBox buttonPane = new HBox();
    buttonPane.setSpacing(10);
    for( int i=0 ; i<buttons.size() ; i++ ){
      buttons.get(i).setOnAction( actionHandler );
    buttonPane.getChildren().setAll( buttons );
    root.setBottom( buttonPane );
  public int show( double screenX, double screenY ){
    setX( screenX ); setY( screenY );
    show();
    MyWindowEventDispatcher dispatcher =  new MyWindowEventDispatcher( stage );
    setEventDispatcher( dispatcher );
    while(true){
      event = dispatcher.dispatchEvent( event, tail );
      EventType<? extends Event> type = event.getEventType();
      if( type==WindowEvent.WINDOW_HIDDEN ){
        break;
    return( rc );
  EventHandler<ActionEvent> actionHandler = new EventHandler<ActionEvent>() {
    public void handle( ActionEvent e ){
      EventTarget src = e.getTarget();
      rc = buttons.indexOf( src );
      stage.hide();
  class MyWindowEventDispatcher extends WindowEventDispatcher {
    public MyWindowEventDispatcher( Window window ){
      super( window );
    public Event dispatchEvent( Event event, EventDispatchChain tail) {
      ModalDialog.this.event = dispatchCapturingEvent( event );
      ModalDialog.this.tail = tail;
      return( event );
}A sample code to invoke ModalDialog
import java.util.ArrayList;
import javax.swing.JOptionPane;
import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.stage.Stage;
import javafx.stage.WindowEvent;
public class WindowEvent06 extends Application {
  Stage mainStage;
  public void start(Stage stage) throws Exception {
    Group root = new Group();
    Scene scene = new Scene(root);
    stage.setScene(scene);
    stage.setTitle("WindowEvent06");
    mainStage = stage;
    stage.setOnCloseRequest(new EventHandler<WindowEvent>() {
      public void handle(WindowEvent e){
        ModalDialog dialog = new ModalDialog( mainStage, "Question" );
        Button yes = new Button( "Yes" );
        Button no  = new Button( "No" );
        ArrayList<Button> buttons = new ArrayList<>();
        buttons.add(yes); buttons.add(no);
        Label msg = new Label( "Really Exit ?" );
        Group groupInDialog = new Group();
        groupInDialog.getChildren().add( msg );
        dialog.setContents( groupInDialog, buttons );
        int ans = dialog.show( 300, 300 );
        System.out.println("returned from a modal dialog");
        if( ans == 1 ){
          e.consume(); // this blocks window closing
    stage.show();
  public static void main(String[] args) {
    launch(args);
}

Answer 1

Hi,
The logic what you follows is some what in the right direction but need to have some changes.
What I would say is, first consume the windowClose event. Then open the dialog box and close the parent accordingly.
So after refactoring your code.
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.stage.Modality;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
public class ModalDialog extends Stage {
     Stage owner;
     Stage stage;
     BorderPane root;
  public ModalDialog( Stage owner, String title){
    root = new BorderPane();
    stage = this;
    this.owner = owner;
    initModality( Modality.APPLICATION_MODAL );
    initOwner( owner );
    initStyle( StageStyle.UTILITY );
    setTitle( title );
    setContents();
  public void setContents(){
    Scene scene = new Scene(root,150,150);
    setScene(scene);
    Group groupInDialog = new Group();
    groupInDialog.getChildren().add( new Label("Really Exit ?") );
    root.setCenter( groupInDialog );
    Button yes = new Button( "Yes" );
    yes.setOnAction(new EventHandler<ActionEvent>() {
          @Override
          public void handle(ActionEvent paramT) {
               stage.close(); // Closing the pop up.
               owner.close(); // Closing the parent stage also.
    Button no  = new Button( "No" );
    no.setOnAction(new EventHandler<ActionEvent>() {
          @Override
          public void handle(ActionEvent paramT) {
               stage.close(); // Closing the pop up only
    HBox buttonPane = new HBox();
    buttonPane.setSpacing(10);
    buttonPane.getChildren().addAll(yes,no);
    root.setBottom(buttonPane);
    stage.show();
}And the main class to check this implementation is
import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.stage.Stage;
import javafx.stage.WindowEvent;
public class WindowEvent06 extends Application {
  public void start(final Stage stage) throws Exception {
    Group root = new Group();
    Scene scene = new Scene(root);
    stage.setScene(scene);
    stage.setTitle("WindowEvent06");
    stage.setOnCloseRequest(new EventHandler<WindowEvent>() {
      public void handle(final WindowEvent e){
         e.consume(); // Consuming the event by default.
         new ModalDialog( stage, "Question");
    stage.show();
  public static void main(String[] args) {
    launch(args);
}I hope the above code will give you some idea what i mean. :)
Happy Coding !!
Regards,
Sai Pradeep Dandem.
Edited by: Sai Pradeep Dandem on Jan 20, 2012 4:03 AM