Deploy Containers Close to Your Users

This Engineering Education (EngEd) Program is supported by Section.

Instantly deploy containers globally. Section is affordable, simple and powerful.

Get Started for Free.

Creating an Animated JavaFX Field Validation Alert

October 12, 2021

A good interface is important because it enhances the interaction between the user and software. Animations improve the quality of an application. It is also a fun way of providing feedback.

Modern authentication forms have evolved from ancient static types to more interactive types.

Today, they include aspects such as validation, styling, and animations. These features improve the interaction process.

In this article, we will discuss input validations, effects, and animations based on user interaction.

Table of Content


To follow along, you should have:

  • Some basic understanding of the Java programming language
  • Java SDK installed on the machine
  • A Java IDE is installed on the machine. I recommend using the latest IntelliJ IDEA Community version.

Create a new project

Open the IDE and then create a new project. Under the project type options, select JavaFX.

Add the following settings in the right-hand side window:

  • Name: Login
  • Group: authentication
  • Artifact: Login
  • Project SDK: You can set the latest SDK version installed on your system.

These are shown in the image below:

new javafx project

Click on the Next button, then select the BootstrapFX, ControlsFX, and FormsFX checkboxes on the dependencies window. BootstrapFX helps in styling the form.

The styling is similar to CSS. ControlsFX enables certain controls in the project. These include TextFields, PasswordFields, Labels, DatePickers, and many others. Finally, FormFX allows one to design forms easily.

The above steps are highlighted in the image below:


The newly created project has the following folder structure:

Folder Structure

├── src
│   ├── main
│       ├── java
│          └── authentication
│             └── login
│                 ├──
│                 └──
│       └── resources
│          └── authentication
│             └── login
│                 └── hello-view.fxml
├── login.iml
└── pom.xml

Open the hello-view.fxml file, which contains the contents of the page to be displayed. Near the status bar, there is a button adjacent to the Text button.

Click on it to view the FXML file using Scene Builder. If it displays the Failed to open the file in Scene Builder error, click on Download SceneBuilder.

Download the Scene Builder

Project view in scene builder

When you run the application, it will open a new application window. In this UI, there is a button that returns a new text when clicked.

The image below shows the output:

Running the first project

lose the application for the next steps.

Create the Login form

Modify the Scene

In the file, add the following:

  • Change the Title of the window to ‘Login Form’.
  • Ensure that the width of the scene is 400 by 600 pixels.
  • Add an icon in the title tab of the JavaFX project. Download the icon file here.

These changes are shown below:

package authentication. login;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.image.Image;
import javafx.stage.Stage;


public class HelloApplication extends Application {
    public void start(Stage stage) throws IOException {
        FXMLLoader fxmlLoader = new FXMLLoader(HelloApplication.class.getResource("hello-view.fxml"));
        // Set the scene width and height to 400 and 600 respectively
        Scene scene = new Scene(fxmlLoader.load(), 400, 600);
        // Set the name of the window to 'Login Form'
        stage.setTitle("Login Form");
        // Add an Icon to the title bar
        stage.getIcons().add(new Image(HelloApplication.class.getResourceAsStream("icon.png")));

    public static void main(String[] args) {

Designing the view

Open up the hello-view.fxml file using the Scene Builder. Delete the VBOX and the element in it.

Then, drag and drop an AnchorPane where the VBox was deleted. This new AnchorPane will hold other controls. The AnchorPane will have the following:


fx-text-fill: #8ecae6 Pref Width: 400 Pref Height: 600

The above layout allows it to fit perfectly in the scene. Drag and drop a label from the controls tab into the AnchorPane in the centre of the SceneBuilder. The label will have the following:


Text: LOGIN Font: System 25px Bold


-fx-text-fill: #219ebc


Pref Width: 100 Pref Height: 20 Layout X: 150 Layout Y: 40

When viewed using the ‘Text’ view, the following code will be generated automatically:

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.geometry.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.image.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.shape.*?>
<?import javafx.scene.text.*?>

<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="600.0" prefWidth="400.0" style="-fx-background-color: #8ecae6;" xmlns="" xmlns:fx="" fx:controller="authentication.login.HelloController">
  <!-- Contents inside the XML file -->
     <!-- Title -->
      <Label layoutX="150.0" layoutY="40.0" prefHeight="20.0" prefWidth="100.0" style="-fx-text-fill: #219ebc;" text="LOGIN">
            <Font name="System Bold" size="25.0" />

Navigate to this link and download the panda image. The image will be placed in the scene to beautify it.

Once downloaded, copy and paste the image into the folder containing the FXML file. Then, drag and drop an ImageView into the AnchorPane. This control will hold or load the image.

Next, add the following properties to the ImageView:


Image: panda.png Font: System 25px Bold


Fit Width: 300 Fit Height: 300 Layout X: 90 Layout Y: 57

The Scene Builder generates the code shown below:

<ImageView fitHeight="300.0" fitWidth="300.0" layoutX="90.0" layoutY="57.0" pickOnBounds="true" preserveRatio="true">
      <Image url="@panda.png" />
      <Rectangle2D />

Now, add a Rectangle from the Shapes category. It should have the following properties:


Arc Width: 5 Fill: #b9eaf8 Stroke: #a3a3a3 Stroke Width: 2 Stroke Line Cap: Round Fill: BEVEL


Width: 370 Height: 320 Layout X: 15 Layout Y: 260

The above rectangle will distinguish the input region from other areas on the form. The generated rectangle code is shown below:

<Rectangle arcHeight="5.0" arcWidth="5.0" fill="#b9eaf8" height="320.0" layoutX="15.0" layoutY="260.0" stroke="#a3a3a3" strokeLineCap="ROUND" strokeLineJoin="BEVEL" strokeType="INSIDE" strokeWidth="2.0" width="370.0" />

Add a Label using the following properties:

<!-- A label to show the start of inputs -->
<Label layoutX="120.0" layoutY="290.0" text="Enter your details below" textFill="#023047">
      <Font name="System Bold" size="14.0" />

Add a TextField for the username and email. It has the following configurations:


Prompt Text: Username / Email Font: System 15px


Pref Width: 245 Pref Height: 35 Layout X: 80 Layout Y: 345 fx:id: usernameTextField

Each element in the form or scene should have a unique id.

<!-- Inputs and their icons -->
<TextField fx:id="usernameTextField" layoutX="80.0" layoutY="345.0" prefHeight="35.0" prefWidth="245.0" promptText="Username / Email">
      <Font size="15.0" />

We need to add an icon for the username TextField. It can be downloaded here.

Add an ImageView that will hold the image:


Image: users.png


Fit Width: 35 Fit Height: 35 Layout X: 80 Layout Y: 345 fx:id: usersIcon

<ImageView fx:id="usersIcon" fitHeight="35.0" fitWidth="35.0" layoutX="40.0" layoutY="345.0" pickOnBounds="true" preserveRatio="true">
      <Image url="@users.png" />

Add a PasswordField to capture the user password. It has the following properties:


Prompt Text: Password Font: System 15px


Pref Width: 245 Pref Height: 35 Layout X: 80 Layout Y: 400 fx:id: userPassword

<PasswordField fx:id="userPassword" layoutX="80.0" layoutY="400.0" prefHeight="35.0" prefWidth="245.0" promptText="Password">
      <Font size="15.0" />

We need to add an icon for the above PasswordField. It can be downloaded from here.

After downloading it, add an ImageView to hold it, as shown below:


Image: lock.png Fit Width: 35 Fit Height: 35 Layout X: 40 Layout Y: 400 fx:id: passwordIcon

The SceneBuilder generated code is as follows:

<ImageView fx:id="passwordIcon" fitHeight="35.0" fitWidth="35.0" layoutX="40.0" layoutY="400.0" pickOnBounds="true" preserveRatio="true">
      <Image url="@lock.png" />

Another Label is required to display the error or success messages. The label will not have any content on it.


Font: System 12px Text Fill: RED


Pref Width: 245 Layout X: 80 Layout Y: 445 fx:id: invalidDetails

<!-- A label to display error and success messages -->
<Label fx:id="invalidDetails" layoutX="88.0" layoutY="446.0" prefWidth="245.0" textFill="RED" />

We will need Buttons for various actions. We should first create a cancel button which will close the scene or window when clicked.

Go ahead and add a button from the controls section. The button will have the following properties:


Text: Cancel Font: System 14px Text Fill: #a3a3a3


fx-background-color: transparent fx-border-width: 2 fx-border-color: #a5a5a5


Pref Width: 90 Pref Height: 30 Layout X: 85 Layout Y: 480 fx:id: cancelButton On Action: onCancelButtonClick

The onAction property binds the button to a function.

Next, create a login button using the following attributes:


Text: Login Font: System 15px Text Fill: #a3a3a3 fx-background-color: #0077b6 fx-border-radius: 5 Pref Width: 90 Pref Height: 30 Layout X: 225 Layout Y: 480 fx:id: loginButton On Action: onLoginButtonClick

It’s code is shown below:

<Button fx:id="loginButton" layoutX="225.0" layoutY="480.0" mnemonicParsing="false" onAction="#onLoginButtonClick" prefHeight="30.0" prefWidth="90.0" style="-fx-background-color: #0077b6; -fx-border-radius: 5;" text="Login" textFill="WHITE">
      <Font size="15.0" />

Add a reset password button, as demonstrated below:


Text: Login Font: System 12px Text Fill: #a3a3a3 fx-background-color: transparent fx-border-radius: 5 Pref Width: 140 Pref Height: 25 Layout X: 120 Layout Y: 530 fx:id: forgotButton

<Button fx:id="forgotButton" layoutX="120.0" layoutY="533.0" mnemonicParsing="false" prefHeight="25.0" prefWidth="141.0" style="-fx-background-color: transparent;" text="Forgot Password?" textFill="#a3a3a3" />

You should see the following output when you run the app:

The final design

Adding form validation

Head over to the file. This file contains functions required in the form. Delete the generated onHelloButtonClick function and welcomeText. The remaining code should look as shown below:

package authentication. login;

import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.stage.Stage;

public class HelloController {

First, import the controls that we added to the form in the previous steps. This is done using the following code:

private TextField usernameTextField;

private PasswordField userPassword;

private Label invalidDetails;

private Button cancelButton, loginButton, forgotButton;

private ImageView usersIcon, passwordIcon;

Add a function to exit the form when the close button is clicked.

// Close form
protected void onCancelButtonClick() {
    Stage stage = (Stage) cancelButton.getScene().getWindow();

The cancel button will invoke the onCancelButtonClick function. This event closes the window immediately.

Next, add some variables inside the HelloController method. They will hold styling that will be reused in the project.

  // Strings which hold css elements to easily re-use in the application
  String successMessage = String.format("-fx-text-fill: GREEN;");
  String errorMessage = String.format("-fx-text-fill: RED;");
  String errorStyle = String.format("-fx-border-color: RED; -fx-border-width: 2; -fx-border-radius: 5;");
  String successStyle = String.format("-fx-border-color: #A9A9A9; -fx-border-width: 2; -fx-border-radius: 5;");

Now, add a function that will be invoked when the Login button is clicked on, as highlighted below:

  // On the login button click
  protected void onLoginButtonClick() throws InterruptedException {

In the function, do the following:

  • Check if the:
    • Username and password are blank
    • Password has less than four characters

Here is the code:

// In case the Username and Password fields are left blank then display the error message
if (usernameTextField.getText().isBlank() || userPassword.getText().isBlank()) {

// When the username and password are blank
if (usernameTextField.getText().isBlank() || userPassword.getText().isBlank()) {
    invalidDetails.setText("The Login fields are required!");

} else // When only the username is blank
if (usernameTextField.getText().isBlank()) {
    invalidDetails.setText("The Username or Email is required!");
} else // When only the password is blank
    if (userPassword.getText().isBlank()) {
        invalidDetails.setText("The Password is required!");
} else // Check if password is less than four characters, if so display error message
  if (userPassword.getText().length() < 4) {
      invalidDetails.setText("The Password can't be less than 4 characters!");
// If all login details are entered as required then display success message
else {
    invalidDetails.setText("Login Successful!");

When you run the application, and there is no input, the project looks as shown below:

When there is no input

When the username is blank, the program will show the following error:

When there is no username input

When there is no password, the error looks as shown below:

When there is no password input

When the password is less than four characters, the error appears as follows:

When the password is less than four

When the username and password are meet the outline criteria, the following output is shown:

When the login is successful

Animating the user interface

The AnimateFX library is required to add animations in the JavaFX project. First, check out AnimateFx’s supported animations here.

Check the dependencies installed or used in the project by clicking on the Dependencies button near the status bar, then search for AnimateFX and add it to the project:

AnimateFX dependency

Wait for a few minutes for the download to complete then reload the file or IDE. To determine if it was installed, check the Dependencies tab.

After this process, navigate to the file. In the onLoginButtonClick() function and add the code below:

new animatefx.animation.Shake(usernameTextField).play();
new animatefx.animation.Wobble(usersIcon).play();
new animatefx.animation.Shake(userPassword).play();
new animatefx.animation.Wobble(passwordIcon).play();

This code will add a ‘Shake’ animation to the inputs when there is an error. It also adds a ‘Wobble’ animation to the images.

In the procedure that checks if the username is blank, add the following code to it:

new animatefx.animation.Shake(usernameTextField).play();
new animatefx.animation.Pulse(usersIcon).play();

The code adds the ‘Pulse’ and ‘Shake’ effect to the input and icon, respectively.

In the procedure that checks if the username is blank, add the following code:

new animatefx.animation.Shake(userPassword).play();
new animatefx.animation.Wobble(passwordIcon).play();

In the function that checks if the password is less than four characters, add a slightly gentle effect, as illustrated below:

new animatefx.animation.FadeIn(userPassword).play();
new animatefx.animation.Wobble(passwordIcon).play();

It adds a ‘FadeIn’ and a ‘Wobble’ effect to the PasswordField, respectively. Finally, add a small Tada animation to the invalidDetails label in the final’ else’ statement. That animation shows that the process is successful.

Here is the code:

new animatefx.animation.Tada(invalidDetails).play();

The final product is as shown below:

The code for this article can be found in this.


In the article, we have learned:

  • How to create a JavaFX login form.
  • How to apply styling to the application.
  • How to perform input validation.
  • How to add animations on the controls.

Further learning

Peer Review Contributions by: Mercy Meave