Develop Reference

JavaFX Slider Tick Marks Initialized via CSS Disappear

I am using CSS to configure my JavaFX Sliders, then applying the style in code with:
cssSlider.getStyleClass().add("slider-style");
When I first open my window, the tick marks are present on the CSS configured Slider(s). When I close and reopen the window, the tick marks are no longer present.
This following example demonstrates the anomaly using 2 Sliders, one configured directly, the other via CSS. Click the button to hide the window for 2 seconds. Notice that the Slider in which I directly configure the attributes works fine after hiding and re-showing, but the CSS configured Slider loses its tick marks after hiding and re-showing.
Does anyone have any ideas why showing, hiding, and re-showing the window causes the tick marks to vanish from the CSS configured Slider? Am I doing something wrong, or is this a JavaFX bug?
sample.css:
.slider-style {
-fx-show-tick-marks: true;
-fx-snap-to-ticks: true;
-fx-major-tick-unit: 5;
-fx-minor-tick-count: 5;
}
CssExample.java:
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.Slider;
import javafx.scene.layout.GridPane;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
import java.io.IOException;
import java.net.URL;
/**
* This simple example demonstrates that JavaFX Sliders configured with CSS only show their tick marks the first time
* they are shown. If the Slider is hidden, then shown again, the tick marks are gone forever.
*/
public class CssExample extends Application {
#Override
public void start(Stage stage) throws InterruptedException, IOException {
Group root = new Group();
Scene scene = new Scene(root, 400, 200);
stage.setScene(scene);
stage.setTitle("Slider Sample");
scene.setFill(Color.BLACK);
GridPane grid = new GridPane();
grid.setPadding(new Insets(10, 10, 10, 10));
grid.setVgap(10);
grid.setHgap(70);
scene.setRoot(grid);
int rowNumber = 1;
Label directLabel = new Label("Slider from attribute assignment");
GridPane.setConstraints(directLabel, 1, rowNumber++);
grid.getChildren().add(directLabel);
Slider directSlider = new Slider();
GridPane.setConstraints(directSlider, 1, rowNumber++);
grid.getChildren().add(directSlider);
directSlider.setShowTickMarks(true);
directSlider.setSnapToTicks(true);
directSlider.setMajorTickUnit(5);
directSlider.setMinorTickCount(5);
Label cssLabel = new Label("Slider from CSS (tick marks disappear after hidden)");
GridPane.setConstraints(cssLabel, 1, rowNumber++);
grid.getChildren().add(cssLabel);
Slider cssSlider = new Slider();
GridPane.setConstraints(cssSlider, 1, rowNumber++);
grid.getChildren().add(cssSlider);
URL url = getClass().getResource("sample.css");
String cssString = url.toExternalForm();
scene.getStylesheets().add(cssString);
cssSlider.getStyleClass().add("slider-style");
Button button = new Button("Hide for 2 Seconds");
GridPane.setConstraints(button, 1, rowNumber++);
grid.getChildren().add(button);
button.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent e) {
stage.hide();
stage.show();
}
});
stage.show();
}
public static void main(String[] args) {
launch(args);
}
}

is this a JavaFX bug?
Yes.
See: https://github.com/openjdk/jfx/blob/fdc88341f1df8fb9c99356ada54b25124b77ea6e/modules/javafx.controls/src/main/java/javafx/scene/control/skin/SliderSkin.java#L398
It is a bug in the internal implementation of the setShowTickMarks method of SliderSkin (verified in JavaFX 18.0.1).
Test case:
import javafx.animation.PauseTransition;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Slider;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
import javafx.util.Duration;
import java.io.IOException;
public class CssExample extends Application {
private static final String CSS = // language=CSS
"""
.slider-style {
-fx-show-tick-marks: true;
-fx-snap-to-ticks: true;
-fx-major-tick-unit: 5;
-fx-minor-tick-count: 5;
}
""";
private static final String CSS_INLINE = "data:text/css," + CSS;
#Override
public void start(Stage stage) throws InterruptedException, IOException {
Platform.setImplicitExit(false);
Slider cssSlider = new Slider();
cssSlider.showTickMarksProperty().addListener((observable, oldValue, newValue) ->
System.out.println(cssSlider.showTickMarksProperty())
);
cssSlider.getStyleClass().add("slider-style");
PauseTransition hideAnimation = new PauseTransition(Duration.seconds(2));
hideAnimation.setOnFinished(e -> stage.show());
Button hideWindow = new Button("Hide for 2 Seconds");
hideWindow.setOnAction(e -> {
stage.hide();
hideAnimation.play();
});
Button closeApp = new Button("Close app");
closeApp.setOnAction(e -> Platform.exit());
VBox layout = new VBox(
10,
cssSlider, hideWindow, closeApp
);
layout.setPadding(new Insets(10));
layout.setPrefSize(400, 120);
Scene scene = new Scene(layout);
scene.getStylesheets().add(CSS_INLINE);
stage.setScene(scene);
stage.show();
}
public static void main(String[] args) {
launch(args);
}
}
Test output:
BooleanProperty [bean: Slider#132908b9[styleClass=slider slider-style], name: showTickMarks, value: true]
BooleanProperty [bean: Slider#132908b9[styleClass=slider slider-style], name: showTickMarks, value: false]
BooleanProperty [bean: Slider#132908b9[styleClass=slider slider-style], name: showTickMarks, value: true]
It switches showTicks from true to false, and back to true, which triggers the bug.
In the current implementation for the setShowTicks method:
private void setShowTickMarks(boolean ticksVisible, boolean labelsVisible) {
showTickMarks = (ticksVisible || labelsVisible);
Slider slider = getSkinnable();
if (showTickMarks) {
if (tickLine == null) {
tickLine = new NumberAxis();
tickLine.setAutoRanging(false);
tickLine.setSide(slider.getOrientation() == Orientation.VERTICAL ? Side.RIGHT : (slider.getOrientation() == null) ? Side.RIGHT: Side.BOTTOM);
tickLine.setUpperBound(slider.getMax());
tickLine.setLowerBound(slider.getMin());
tickLine.setTickUnit(slider.getMajorTickUnit());
tickLine.setTickMarkVisible(ticksVisible);
tickLine.setTickLabelsVisible(labelsVisible);
tickLine.setMinorTickVisible(ticksVisible);
// add 1 to the slider minor tick count since the axis draws one
// less minor ticks than the number given.
tickLine.setMinorTickCount(Math.max(slider.getMinorTickCount(),0) + 1);
if (slider.getLabelFormatter() != null) {
tickLine.setTickLabelFormatter(stringConverterWrapper);
}
getChildren().clear();
getChildren().addAll(tickLine, track, thumb);
} else {
tickLine.setTickLabelsVisible(labelsVisible);
tickLine.setTickMarkVisible(ticksVisible);
tickLine.setMinorTickVisible(ticksVisible);
}
}
else {
getChildren().clear();
getChildren().addAll(track, thumb);
// tickLine = null;
}
getSkinnable().requestLayout();
}
The first time it shows the ticks it will do this:
getChildren().clear();
getChildren().addAll(tickLine, track, thumb);
Then, when the ticks are hidden, it will do this:
getChildren().clear();
getChildren().addAll(track, thumb);
Then, when the ticks are supposed to be shown again, the tickLine is not added back to the children, so it never shows the ticks again.

JavaFX - Why does changing the header text of a dialog make the button bar invisible?

Here is a small sample from my custom dialog, which is meant to display the progress of a running javafx.concurrent.Task.
DialogPane pane = this.getDialogPane()
pane.getButtonTypes().addAll(ButtonType.CANCEL);
pane.headerTextProperty().bind(task.titleProperty());
pane.contentTextProperty().bind(task.messageProperty());
For some reason, the buttons in the button bar disappeared, but only after some text updated. After further investigation, I found that binding the header text of a dialog seems to remove all the buttons in the button bar. Why would this happen, and what would I do to stop the buttons from being hidden?
EDIT: Here's an MCVE demonstrating the problem.
import javafx.application.Application;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.concurrent.Task;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.layout.StackPane;
import javafx.stage.Modality;
import javafx.stage.Stage;
public class MCVE extends Application {
public static class CustomDialog extends Dialog<ButtonType> {
public CustomDialog(Task<?> task) {
this.initModality(Modality.APPLICATION_MODAL);
DialogPane pane = this.getDialogPane();
{
pane.getButtonTypes().addAll(ButtonType.CANCEL);
pane.headerTextProperty().bind(task.titleProperty());
}
setOnCloseRequest(event -> {
if (task.isRunning()) event.consume();
});
}
}
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage stage) {
StackPane root = new StackPane();
Button starter = new Button("Showcase");
starter.setMaxSize(Double.MAX_VALUE, Double.MAX_VALUE);
root.getChildren().add(starter);
Scene scene = new Scene(root, 500, 500);
stage.setScene(scene);
stage.show();
starter.setOnAction(event -> {
Task<Void> task = new Task<>() {
#Override
protected Void call() throws Exception {
updateTitle("Before loop");
try {
Thread.sleep(1000);
} catch (InterruptedException ignored) {
if (isCancelled()) return null;
}
for (int i = 1; i <= 20; i++) {
updateTitle("loop " + i);
try {
Thread.sleep(1000);
} catch (InterruptedException ignored) {
if (isCancelled()) return null;
}
}
return null;
}
};
Thread worker = new Thread(task);
worker.start();
new CustomDialog(task).showAndWait();
});
}
}

It appears that the issue needs fixing on JavaFX's end. In fact, the button bar is simply pushed out of view. There is a relatively decent workaround though. Dialog internally uses a styled GridPane to display header text and graphics, so I simply replicated that using an external GridPane and instead bound to the textProperty() of a Label.
public static class CustomDialog extends Dialog<ButtonType> {
public CustomDialog(Task<?> task) {
DialogPane pane = this.getDialogPane(); {
pane.getButtonTypes().addAll(ButtonType.CANCEL);
//construct custom header
GridPane headerRoot = new GridPane(); {
Label headerText = new Label();
//headerText is the label containing the header text
headerText.textProperty().bind(task.titleProperty());
headerRoot.add(headerText, 0, 0);
}
headerRoot.getStyleClass().addAll("header-panel");
pane.setHeader(headerRoot);
pane.setContentText("Placeholder content");
pane.getScene().getWindow().setOnCloseRequest(event -> {
if (!task.isDone()) {
event.consume();
}
});
}
}
It looks exactly the same as a default dialog, without the issue mentioned in the question above.

JavaFX Dynamic Code

I want to immediately after increasing the value of i appear in the label
Example:
-in i=0 show 0
-in i=1 show 01
-in i=2 show 012
Can You Help me
import javafx.application.Application;
import javafx.scene.control.Label;
import javafx.scene.control.Button;
import javafx.scene.layout.Pane;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class Example extends Application{
#Override
public void start (Stage primaryStage) {
Pane pane=new Pane();
Label label=new Label();
Button bt=new Button("Start");
pane.getChildren().addAll(bt,label);
bt.setOnAction(e->{
for (int i=0;i<10000000;i++) label.setText(label.getText()+i);
});
Scene scene = new Scene(pane,1000,500);
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}

The problem is that you update the label's value while you are on the user interface's thread. JavaFX works with a model where the updates are done at each 'tick' (60 fps). All the updates done are only visible once your eventhander's code has finished.
Additionally, given that this is a long running task it will result in an unresponsive user interface.
You should use a Worker to do the long running task. See the tutorial on asynchronous processing. Note that it will not guarantee that you will see all values as the worker can be quicker than the user interface updates and the system will coalesce these updates.

You can use Timeline to accomplish this task.
import java.util.concurrent.atomic.AtomicLong;
import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.Priority;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
import javafx.util.Duration;
/**
*
* #author blj0011
*/
public class JavaFXApplication177 extends Application
{
#Override
public void start(Stage primaryStage)
{
AtomicLong i = new AtomicLong();
Label label = new Label();
Button btn = new Button();
Timeline timeline = new Timeline(new KeyFrame(Duration.seconds(.5), (ActionEvent event) -> {//This controls how fast this should run. This example happens every half of a second
label.setText(label.getText() + Long.toString(i.getAndIncrement()));
}));
timeline.setCycleCount(10000000);//This controls the amount of time this should run
timeline.setOnFinished(event -> {//This tells what to do once cycle count is reached
btn.setDisable(false);
});
btn.setText("Start");
btn.setOnAction((ActionEvent event) -> {
btn.setDisable(true);
timeline.play();
});
StackPane stackPane = new StackPane(label);
VBox root = new VBox(stackPane, new StackPane(btn));
VBox.setVgrow(stackPane, Priority.ALWAYS);
Scene scene = new Scene(root, 300, 250);
primaryStage.setTitle("Hello World!");
primaryStage.setScene(scene);
primaryStage.show();
}
/**
* #param args the command line arguments
*/
public static void main(String[] args)
{
launch(args);
}
}

import javafx.application.Application;
import javafx.application.Platform;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
public class Test5 extends Application {
private String text = "";
private int i;
#Override // Override the start method in the Application class
public void start(Stage primaryStage) {
StackPane pane = new StackPane();
Label lblText = new Label("");
pane.getChildren().add(lblText);
new Thread(new Runnable() {
#Override
public void run() {
try {
for (i=0;i<10000;i++) {
Platform.runLater(new Runnable() { // Run from JavaFX GUI
#Override
public void run() {
lblText.setText(lblText.getText()+i);
}
});
Thread.sleep(200);
}
}
catch (InterruptedException ex) {
}
}
}).start();
Scene scene = new Scene(pane, 200, 50);
primaryStage.setTitle("FlashText"); // Set the stage title
primaryStage.setScene(scene); // Place the scene in the stage
primaryStage.show(); // Display the stage
}
}

Service<Void> service = new Service<Void>() {
#Override
protected Task<Void> createTask() {
return new Task<Void>() {
#Override
protected Void call() throws Exception {
//Your First Task #1
//Here UI won't be interrupted
Platform.runLater(new Runnable() {
#Override
public void run() {
//Your Second Task After Completion Of First One #2
}
});
return null;
}
};
}
};
service.start();
}
#1. The task that you want to perform in the background ex. loading the data has to be placed here. It's working great for me.
#2. Once the background task is finished this thread will be executed so Ui and background thread will run separately and smoothly.
I know it's too late for this answer but I just wanted to share what I did this might help!

setOnMouseDragged not working on browser view

I'm writing a simple application in java using JxBrowser engine but i'm stuck at the very beginning. In my code, there is an undecorated stage that i want to make it draggable. To do so, searched and found the following link:
How to drag undecorated window
So I set mousePressed and MouseDragged event on stackPane but only mousePressed event gets fired and mouseDragged event no way gets fired. Any idea of what's the problem?
Thanks in advance.
import com.teamdev.jxbrowser.chromium.Browser;
import com.teamdev.jxbrowser.chromium.javafx.BrowserView;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
private static double xOffset = 0;
private static double yOffset = 0;
public class Main extends Application {
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage primaryStage) {
Platform.setImplicitExit(false);
Browser browser = new Browser();
BrowserView browserView = new BrowserView(browser);
StackPane pane = new StackPane();
pane.getChildren().add(browserView);
Scene scene = new Scene(pane, 380, 500);
primaryStage.initStyle(StageStyle.UNDECORATED);
primaryStage.setScene(scene);
pane.setOnMousePressed(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent event) {
System.out.println("mouse pressed");
xOffset = primaryStage.getX() - event.getScreenX();
yOffset = primaryStage.getY() - event.getScreenY();
}
});
pane.setOnMouseDragged(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent event) {
System.out.println("mouse dragged");
primaryStage.setX(event.getScreenX() + xOffset);
primaryStage.setY(event.getScreenY() + yOffset);
}
});
primaryStage.show();
}
}

Since jxbrowser requires license I couldn't test it... So I replaced that with Label and it works fine.. So my guess is that you are trying to drag by clicking on the browser itself and not the StackPane.. Try clicking at the corner of the Stage or else add stack pane to VBox and setPadding to it.. And try clicking at the corner.. If your clicking on the browser then browser's mouse events will be trigerred..
Proof:
The correct code
package RezRem;
import com.teamdev.jxbrowser.chromium.Browser;
import com.teamdev.jxbrowser.chromium.javafx.BrowserView;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
public class Main extends Application {
private static double xOffset = 0;
private static double yOffset = 0;
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage primaryStage) {
Platform.setImplicitExit(false);
Browser browser = new Browser();
BrowserView browserView = new BrowserView(browser);
StackPane pane = new StackPane();
pane.getChildren().add(browserView);
pane.setPadding(new Insets(10,10,10,10));
Scene scene = new Scene(pane, 380, 500);
primaryStage.initStyle(StageStyle.UNDECORATED);
primaryStage.setScene(scene);
pane.setOnMousePressed(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent event) {
System.out.println("mouse pressed");
xOffset = primaryStage.getX() - event.getScreenX();
yOffset = primaryStage.getY() - event.getScreenY();
}
});
pane.setOnMouseDragged(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent event) {
System.out.println("mouse dragged");
primaryStage.setX(event.getScreenX() + xOffset);
primaryStage.setY(event.getScreenY() + yOffset);
}
});
browser.loadURL("http://www.google.com");
primaryStage.show();
}
}
Reason
The jxbrowser extends till the edge so the stack pane wasn't on top neither was it visible on the sides so the mouse listener's never got triggered by setting the padding of stack pane there was 10px gap on all four sides where, if clicked, triggered the mouse events and thereby solves the problem..

I ran into this same problem. I ended up solving it by using the setMouseEventsHandler method on BrowserView which does seem to receive all the events you need (although it does not seem to receive MouseEvent.MOUSE_DRAGGED events unless they have been rebranded as MouseEvent.MOUSE_MOVED events).
Rectangle[] dragIncludeRects = ...; // The area which is draggable (ie the title bar)
Rectangle[] dragExcludeRects = ...; // Exclusions (ie a close button on the title bar)
BrowserView popupView = ...;
JDialog popupFrame = ...; // could also be JFrame
Point dragOffset = null;
popupView.setMouseEventsHandler(new InputEventsHandler<MouseEvent>() {
public boolean handle(MouseEvent event) {
switch(event.getID()) {
case MouseEvent.MOUSE_PRESSED:
if (
dragIncludeRects.exists((rect) => rect.contains(event.getPoint())) &&
!dragExcludeRects.exists((rect) => rect.contains(event.getPoint()))
) {
dragOffset = SwingUtilities.convertPoint(
popupView, event.getPoint(), popupFrame);
} else {
dragOffset = null;
}
break;
case MouseEvent.MOUSE_RELEASED:
dragOffset = null;
break;
case MouseEvent.MOUSE_MOVED:
if (dragOffset != null) {
// Note I tried using the position from the event but it doesn't work well
val position = MouseInfo.getPointerInfo().getLocation();
popupFrame.setLocation(position.x - offset.x, position.y - offset.y);
}
}
return false;
}
})

How to force Java FX scene refresh?

I have an Java FX scene with a start button and several rectangles which represent the tiles of a map. I also have drawn a sphere which represents my explorer (it has to explore the map), but I am having difficulties with running the animation.
In my OnMouseClicked handler for the start button, I start an algorithm for exploring the map which changes the position of the sphere and the colors of the tiles which have been visited. The problem is that the scene won't update itself while the algorithm is running, so I only get to see how the final scene will look like (after the algorithm has stopped running). How can I force a scene update so I can see all the color changes sequentially?
Later edit:
import javafx.application.Application;
import javafx.event.Event;
import javafx.event.EventHandler;
import javafx.event.EventType;
import javafx.geometry.Insets;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.image.Image;
import javafx.scene.layout.HBox;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;
public class Test extends Application {
private static final double boxOuterSize = 50;
private static final double boxInnerSize = 48;
private static final double boxCornerRadius = 20;
private Stage applicationStage;
private Scene applicationScene;
private static double sceneWidth = 1024;
private static double sceneHeight = 800;
private static HBox container = new HBox();
private static Group root = new Group();
private Rectangle[] rectangles = new Rectangle[10];
#Override
public void start(Stage mainStage) throws Exception {
applicationStage = mainStage;
container.setSpacing(10);
container.setPadding(new Insets(10, 10, 10, 10));
try {
applicationScene = new Scene(container, sceneWidth, sceneHeight);
applicationScene.addEventHandler(EventType.ROOT,(EventHandler<? super Event>)this);
applicationScene.setFill(Color.WHITE);
} catch (Exception exception) {
System.out.println ("exception : "+exception.getMessage());
}
applicationStage.setTitle("HurtLockerRobot - Tema 3 IA");
applicationStage.getIcons().add(new Image("icon.png"));
applicationStage.setScene(applicationScene);
for(int i=0; i<10; i++) {
Rectangle r = new Rectangle();
r.setFill(Color.BLUE);
r.setX(i * boxOuterSize);
r.setY(0);
r.setWidth(boxInnerSize);
r.setHeight(boxInnerSize);
r.setArcHeight(boxCornerRadius);
r.setArcWidth(boxCornerRadius);
r.setSmooth(true);
rectangles[i] = r;
root.getChildren().add(rectangles[i]);
}
container.getChildren().add(root);
Button startButton = new Button("Start");
startButton.setOnMouseClicked(new EventHandler<Event>() {
#Override
public void handle(Event arg0) {
for(int i=0; i<10; i++) {
rectangles[i].setFill(Color.RED);
// TODO: some kind of scene refresh here
}
}
});
container.getChildren().add(startButton);
applicationStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
Initially all the rectangles are blue. The behavior I want to obtain here is to see the rectangles changing colors sequentially. The problem is that I only get to see the end result (all the rectangles change their color at the same time).

This is an old question and it caught my eye since this is a very general issue faced by people new to JavaFX.
The problem that OP is facing is because he updates all the rectangles at once, without waiting.
OP can wait by either creating a new Thread, put the thread on sleep for an estimated seconds for every iteration of the loop and then update the color of the rectangle on JavaFX application thread by using Platform.runLater.
#Override
public void handle(Event arg0) {
new Thread(() -> {
for(int i=0; i<10; i++) {
try {
Thread.sleep(1000); // Wait for 1 sec before updating the color
} catch (InterruptedException e) {
e.printStackTrace();
}
int finalI = i;
Platform.runLater(() -> rectangles[finalI].setFill(Color.RED));// Update on JavaFX Application Thread
}
}).start();
The above snippet is more of a traditional way of doing things. If we want to use the "JavaFX" ways of doing things, we can achieve the same by using an Animation.
Below is a code snippet which will wait for x-seconds before changing the color of the rectangle. It doesn't need any extra thread since the wait is handled by PauseTransition applied for each rectangle.
startButton.setOnMouseClicked(new EventHandler<Event>() {
#Override
public void handle(Event arg0) {
for(int i=0; i<10; i++) {
PauseTransition pauseTransition = new PauseTransition(Duration.seconds(i));
int finalI = i;
pauseTransition.setOnFinished(event -> rectangles[finalI].setFill(Color.RED));
pauseTransition.play();
}
}
});
It creates a PauseTransition for each rectangle and depending on its index in the array rectangles, it waits for the same number of seconds before updating the color.

This is because of :
exception : Test cannot be cast to javafx.event.EventHandler
Well, I have no idea how Class cast exception came up.
Otherwise, to delay, you can use Thread.sleep().
UPDATE:
Its good to use AnimationTimer to create an animation, you don't need to refresh anything.
Here, I have done a short EG to show color rect using FillTransition.
CODE:
import javafx.animation.FillTransition;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;
import javafx.util.Duration;
public class NewFXMain1 extends Application {
private static final double boxOuterSize = 50;
private static final double boxInnerSize = 48;
private static final double boxCornerRadius = 20;
private Rectangle rectangles = new Rectangle();
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage primaryStage) {
primaryStage.setTitle("rect");
Button btn = new Button();
StackPane root = new StackPane();
Rectangle r = new Rectangle();
r.setFill(Color.BLUE);
r.setX(2 * boxOuterSize);
r.setY(0);
r.setWidth(boxInnerSize);
r.setHeight(boxInnerSize);
r.setArcHeight(boxCornerRadius);
r.setArcWidth(boxCornerRadius);
r.setSmooth(true);
r.localToScene(boxOuterSize, boxOuterSize);
rectangles = r;
root.getChildren().add(rectangles);
btn.setText("display");
btn.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent event) {
FillTransition ft = new FillTransition(Duration.millis(3000), rectangles, Color.RED, Color.BLUE);
ft.setCycleCount(4);
ft.setAutoReverse(true);
ft.play();
}
});
root.getChildren().add(btn);
primaryStage.setScene(new Scene(root, 300, 250));
primaryStage.show();
}
}