Dialogs

Remarks

Dialogs were added in JavaFX 8 update 40.

Alert

Alert is a simple popup that displays a set of buttons and gets an result depending on the button the user clicked:

Example

This lets the user decide, if (s)he really wants to close the primary stage:

@Override
public void start(Stage primaryStage) {
    Scene scene = new Scene(new Group(), 100, 100);

    primaryStage.setOnCloseRequest(evt -> {
        // allow user to decide between yes and no
        Alert alert = new Alert(Alert.AlertType.CONFIRMATION, "Do you really want to close this application?", ButtonType.YES, ButtonType.NO);

        // clicking X also means no
        ButtonType result = alert.showAndWait().orElse(ButtonType.NO);
        
        if (ButtonType.NO.equals(result)) {
            // consume event i.e. ignore close request 
            evt.consume();
        }
    });
    primaryStage.setScene(scene);
    primaryStage.show();
}

Note that the button text is automatically adjusted depending on the Locale.

ChoiceDialog

ChoiceDialog allows the user to pick one item from a list of options.

List<String> options = new ArrayList<>();
options.add("42");
options.add("9");
options.add("467829");
options.add("Other");

ChoiceDialog<String> dialog = new ChoiceDialog<>(options.get(0), options);
dialog.setHeaderText("Choose your favourite number.");
dialog.setTitle("Favourite number?");
dialog.setContentText("Your favourite number:");

Optional<String> choice = dialog.showAndWait();

String s = choice.map(c -> "Other".equals(c) ? 
              "Unfortunately your favourite number is not available!"
              : "Nice! I like " + c + " too!")
           .orElse("You really don't want to tell me, huh?");

System.out.println(s);

Custom Button text

The text displayed in a button can be customized, by creating a ButtonType instance yourself:

ButtonType answer = new ButtonType("42");
ButtonType somethingElse = new ButtonType("54");

Alert alert = new Alert(Alert.AlertType.NONE, "What do you get when you multiply six by nine?", answer, somethingElse);
ButtonType result = alert.showAndWait().orElse(somethingElse);

Alert resultDialog = new Alert(Alert.AlertType.INFORMATION,
                               answer.equals(result) ? "Correct" : "wrong",
                               ButtonType.OK);

resultDialog.show();

TextInputDialog

TextInputDialog allows the to ask the user to input a single String.

TextInputDialog dialog = new TextInputDialog("42");
dialog.setHeaderText("Input your favourite int.");
dialog.setTitle("Favourite number?");
dialog.setContentText("Your favourite int: ");

Optional<String> result = dialog.showAndWait();

String s = result.map(r -> {
    try {
        Integer n = Integer.valueOf(r);
        return MessageFormat.format("Nice! I like {0} too!", n);
    } catch (NumberFormatException ex) {
        return MessageFormat.format("Unfortunately \"{0}\" is not a int!", r);
    }
}).orElse("You really don't want to tell me, huh?");

System.out.println(s);


2016-07-25
2017-02-24
javafx Pedia
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