JavaFX Form Validation - Registration Form Validation Example

In this JavaFX tutorial, we will learn how to validate the Registration/Signup form in JavaFX.

Creating a Registration/Signup form and validating the form fields is a common activity when developing an application.

JavaFX Registration Form Validation Example

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.HPos;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.layout.*;
import javafx.scene.text.Font;
import javafx.scene.text.FontWeight;
import javafx.stage.Stage;
import javafx.stage.Window;

public class Main extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception {
        primaryStage.setTitle("Registration Form JavaFX Application");

        // Create the registration form grid pane
        GridPane gridPane = createRegistrationFormPane();
        // Add UI controls to the registration form grid pane
        addUIControls(gridPane);
        // Create a scene with registration form grid pane as the root node
        Scene scene = new Scene(gridPane, 800, 500);
        // Set the scene in primary stage
        primaryStage.setScene(scene);

        primaryStage.show();
    }


    private GridPane createRegistrationFormPane() {
        // Instantiate a new Grid Pane
        GridPane gridPane = new GridPane();

        // Position the pane at the center of the screen, both vertically and horizontally
        gridPane.setAlignment(Pos.CENTER);

        // Set a padding of 20px on each side
        gridPane.setPadding(new Insets(40, 40, 40, 40));

        // Set the horizontal gap between columns
        gridPane.setHgap(10);

        // Set the vertical gap between rows
        gridPane.setVgap(10);

        // Add Column Constraints

        // columnOneConstraints will be applied to all the nodes placed in column one.
        ColumnConstraints columnOneConstraints = new ColumnConstraints(100, 100, Double.MAX_VALUE);
        columnOneConstraints.setHalignment(HPos.RIGHT);

        // columnTwoConstraints will be applied to all the nodes placed in column two.
        ColumnConstraints columnTwoConstrains = new ColumnConstraints(200,200, Double.MAX_VALUE);
        columnTwoConstrains.setHgrow(Priority.ALWAYS);

        gridPane.getColumnConstraints().addAll(columnOneConstraints, columnTwoConstrains);

        return gridPane;
    }

    private void addUIControls(GridPane gridPane) {
        // Add Header
        Label headerLabel = new Label("Registration Form");
        headerLabel.setFont(Font.font("Arial", FontWeight.BOLD, 24));
        gridPane.add(headerLabel, 0,0,2,1);
        GridPane.setHalignment(headerLabel, HPos.CENTER);
        GridPane.setMargin(headerLabel, new Insets(20, 0,20,0));

        // Add Name Label
        Label nameLabel = new Label("Full Name : ");
        gridPane.add(nameLabel, 0,1);

        // Add Name Text Field
        TextField nameField = new TextField();
        nameField.setPrefHeight(40);
        gridPane.add(nameField, 1,1);


        // Add Email Label
        Label emailLabel = new Label("Email ID : ");
        gridPane.add(emailLabel, 0, 2);

        // Add Email Text Field
        TextField emailField = new TextField();
        emailField.setPrefHeight(40);
        gridPane.add(emailField, 1, 2);

        // Add Password Label
        Label passwordLabel = new Label("Password : ");
        gridPane.add(passwordLabel, 0, 3);

        // Add Password Field
        PasswordField passwordField = new PasswordField();
        passwordField.setPrefHeight(40);
        gridPane.add(passwordField, 1, 3);

        // Add Submit Button
        Button submitButton = new Button("Submit");
        submitButton.setPrefHeight(40);
        submitButton.setDefaultButton(true);
        submitButton.setPrefWidth(100);
        gridPane.add(submitButton, 0, 4, 2, 1);
        GridPane.setHalignment(submitButton, HPos.CENTER);
        GridPane.setMargin(submitButton, new Insets(20, 0,20,0));

        submitButton.setOnAction(new EventHandler<ActionEvent>() {


            @Override
            public void handle(ActionEvent event) {

                String username = nameField.getText().toString();
                String email = emailField.getText().toString();
                String password = passwordField.getText().toString();

                System.out.println("username -> " + username);
                System.out.println("email address -> " + email);
                System.out.println(" Password -> " + password);

                if(nameField.getText().isEmpty()) {
                    showAlert(Alert.AlertType.ERROR, gridPane.getScene().getWindow(), "Form Error!", "Please enter your name");
                    return;
                }
                if(emailField.getText().isEmpty()) {
                    showAlert(Alert.AlertType.ERROR, gridPane.getScene().getWindow(), "Form Error!", "Please enter your email id");
                    return;
                }
                if(passwordField.getText().isEmpty()) {
                    showAlert(Alert.AlertType.ERROR, gridPane.getScene().getWindow(), "Form Error!", "Please enter a password");
                    return;
                }

                showAlert(Alert.AlertType.CONFIRMATION, gridPane.getScene().getWindow(), "Registration Successful!", "Welcome " + nameField.getText());
            }
        });
    }

    private void showAlert(Alert.AlertType alertType, Window owner, String title, String message) {
        Alert alert = new Alert(alertType);
        alert.setTitle(title);
        alert.setHeaderText(null);
        alert.setContentText(message);
        alert.initOwner(owner);
        alert.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}

Let's understand the above source code step by step.

Create a GridPane Layout

    private GridPane createRegistrationFormPane() {
        // Instantiate a new Grid Pane
        GridPane gridPane = new GridPane();

        // Position the pane at the center of the screen, both vertically and horizontally
        gridPane.setAlignment(Pos.CENTER);

        // Set a padding of 20px on each side
        gridPane.setPadding(new Insets(40, 40, 40, 40));

        // Set the horizontal gap between columns
        gridPane.setHgap(10);

        // Set the vertical gap between rows
        gridPane.setVgap(10);

        // Add Column Constraints

        // columnOneConstraints will be applied to all the nodes placed in column one.
        ColumnConstraints columnOneConstraints = new ColumnConstraints(100, 100, Double.MAX_VALUE);
        columnOneConstraints.setHalignment(HPos.RIGHT);

        // columnTwoConstraints will be applied to all the nodes placed in column two.
        ColumnConstraints columnTwoConstrains = new ColumnConstraints(200,200, Double.MAX_VALUE);
        columnTwoConstrains.setHgrow(Priority.ALWAYS);

        gridPane.getColumnConstraints().addAll(columnOneConstraints, columnTwoConstrains);

        return gridPane;
    }

Create Label and Text Field for Username

        // Add Name Label
        Label nameLabel = new Label("Full Name : ");
        gridPane.add(nameLabel, 0,1);

        // Add Name Text Field
        TextField nameField = new TextField();
        nameField.setPrefHeight(40);
        gridPane.add(nameField, 1,1);

Create Label and Text Field for Email

        // Add Email Label
        Label emailLabel = new Label("Email ID : ");
        gridPane.add(emailLabel, 0, 2);

        // Add Email Text Field
        TextField emailField = new TextField();
        emailField.setPrefHeight(40);
        gridPane.add(emailField, 1, 2);

Create Label and Text Field for Password

        // Add Password Label
        Label passwordLabel = new Label("Password : ");
        gridPane.add(passwordLabel, 0, 3);

        // Add Password Field
        PasswordField passwordField = new PasswordField();
        passwordField.setPrefHeight(40);
        gridPane.add(passwordField, 1, 3);

Create Submit Button

        // Add Submit Button
        Button submitButton = new Button("Submit");
        submitButton.setPrefHeight(40);
        submitButton.setDefaultButton(true);
        submitButton.setPrefWidth(100);
        gridPane.add(submitButton, 0, 4, 2, 1);
        GridPane.setHalignment(submitButton, HPos.CENTER);
        GridPane.setMargin(submitButton, new Insets(20, 0,20,0));

Submit Button Event Handling

        submitButton.setOnAction(new EventHandler<ActionEvent>() {

            @Override
            public void handle(ActionEvent event) {
                String username = nameField.getText().toString();
                String email = emailField.getText().toString();
                String password = passwordField.getText().toString();

                System.out.println("username -> " + username);
                System.out.println("email address -> " + email);
                System.out.println(" Password -> " + password);
            }
        });

Form Validation

        submitButton.setOnAction(new EventHandler<ActionEvent>() {


            @Override
            public void handle(ActionEvent event) {

                String username = nameField.getText().toString();
                String email = emailField.getText().toString();
                String password = passwordField.getText().toString();

                System.out.println("username -> " + username);
                System.out.println("email address -> " + email);
                System.out.println(" Password -> " + password);

                if(nameField.getText().isEmpty()) {
                    showAlert(Alert.AlertType.ERROR, gridPane.getScene().getWindow(), "Form Error!", "Please enter your name");
                    return;
                }
                if(emailField.getText().isEmpty()) {
                    showAlert(Alert.AlertType.ERROR, gridPane.getScene().getWindow(), "Form Error!", "Please enter your email id");
                    return;
                }
                if(passwordField.getText().isEmpty()) {
                    showAlert(Alert.AlertType.ERROR, gridPane.getScene().getWindow(), "Form Error!", "Please enter a password");
                    return;
                }

                showAlert(Alert.AlertType.CONFIRMATION, gridPane.getScene().getWindow(), "Registration Successful!", "Welcome " + nameField.getText());
            }
        });

Alert Popup to display an error message

    private void showAlert(Alert.AlertType alertType, Window owner, String title, String message) {
        Alert alert = new Alert(alertType);
        alert.setTitle(title);
        alert.setHeaderText(null);
        alert.setContentText(message);
        alert.initOwner(owner);
        alert.show();
    }

Output

Username validation:

Email address validation:

Password validation:

Registration form validation success:

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