JavaFX: Red border for text field

Question

I have a form with text fields and I want to give them a red border if I click on \"save\" but e.g. nothing was input in required fields, letters for the \"birthday\" field,

Answer 1

The above mentioned solution by James_D works perfectly fine ( but not for JAVAFX 8.0 ). James have already mentioned the code changes for JAVAFX 8.0, i just tried that and it works like a charm. Here is the changed version for JAVAFX 8.0, just incase someone needs a quick reference.All CREDIT GOES TO JAMES_D

import java.util.Collections;

import javafx.application.Application;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.collections.ObservableList;
import javafx.css.PseudoClass;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;

public class ValidatingTextFieldExample extends Application {
private final PseudoClass errorClass = PseudoClass.getPseudoClass("error");
@Override
public void start(Stage primaryStage) {
    GridPane root = new GridPane();
    TextField nameTF = new TextField();
    TextField emailTF = new TextField();

    root.add(new Label("Name:"), 0, 0);
    root.add(nameTF, 1, 0);
    root.add(new Label("Email:"), 0, 1);
    root.add(emailTF, 1, 1);

    setUpValidation(nameTF);
    setUpValidation(emailTF);

    Scene scene = new Scene(root, 250, 150);
    scene.getStylesheets().add(getClass().getResource("text-field-red-border.css").toExternalForm());
    primaryStage.setScene(scene);
    primaryStage.show();
}

private void setUpValidation(final TextField tf) { 
    tf.textProperty().addListener(new ChangeListener() {

        @Override
        public void changed(ObservableValue observable,
                String oldValue, String newValue) {
            validate(tf);
        }

    });

    validate(tf);
}

private void validate(TextField tf) {
    ObservableList styleClass = tf.getStyleClass();
    if (tf.getText().trim().length()==0) {
        tf.pseudoClassStateChanged(errorClass, true);
    }
    else{
        tf.pseudoClassStateChanged(errorClass, false);
    }

}

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

}