Example of using Bindings (extensively) for validation in JavaFX. Maybe a basis for thinking about a validation framework.

application.css

.root {
	error-color: #ffa0a0 ;
}
.text-field:validation-error {
	-fx-background-color: error-color ;
}
.label.error-instructions {
	-fx-text-fill: error-color ;
}

tabvalidation.TabValidation.fxml

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

<?import java.lang.*?>
<?import javafx.geometry.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.Tab?>
<?import javafx.scene.control.TabPane?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.control.Tooltip?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.layout.BorderPane?>
<?import javafx.scene.layout.VBox?>
<?import javafx.scene.web.*?>

<BorderPane xmlns:fx="http://javafx.com/fxml" fx:controller="tabvalidation.Controller">
  <center>
    <TabPane fx:id="tabPane">
      <tabs>
        <Tab fx:id="nameTab" text="Name">
          <content>
            <BorderPane>
              <bottom>
                <Label fx:id="nameTabErrorInstructions" styleClass="error-instructions" text="Items in red need attention" BorderPane.alignment="CENTER">
                  <BorderPane.margin>
                    <Insets bottom="5.0" left="5.0" right="5.0" top="5.0" fx:id="x1" />
                  </BorderPane.margin>
                </Label>
              </bottom>
              <center>
                <GridPane hgap="10.0" vgap="10.0">
                  <children>
                    <Label text="First Name:" GridPane.columnIndex="0" GridPane.rowIndex="0" />
                    <TextField fx:id="firstNameTextField" GridPane.columnIndex="1" GridPane.rowIndex="0">
                      <tooltip>
                        <Tooltip text="First name" />
                      </tooltip>
                    </TextField>
                    <Label text="Last Name:" GridPane.columnIndex="0" GridPane.rowIndex="1" />
                    <TextField fx:id="lastNameTextField" GridPane.columnIndex="1" GridPane.rowIndex="1" />
                  </children>
                  <columnConstraints>
                    <ColumnConstraints halignment="RIGHT" hgrow="NEVER" />
                    <ColumnConstraints halignment="LEFT" hgrow="ALWAYS" />
                  </columnConstraints>
                  <padding>
                    <Insets bottom="10.0" left="10.0" right="10.0" top="10.0" />
                  </padding>
                  <BorderPane.margin>
                    <Insets />
                  </BorderPane.margin>
                </GridPane>
              </center>
              <top>
                <TitledPane fx:id="nameTabErrorList" animated="false" expanded="false">
                  <content>
                    <VBox fx:id="nameTabErrorMessages" spacing="5.0" />
                  </content>
                </TitledPane>
              </top>
            </BorderPane>
          </content>
        </Tab>
        <Tab fx:id="contactTab" text="Contact">
          <content>
            <BorderPane>
              <bottom>
                <Label id="nameTabErrorInstructions" fx:id="contactTabErrorInstructions" alignment="CENTER" styleClass="error-instructions" text="Items in red need attention" BorderPane.alignment="CENTER" BorderPane.margin="$x1" />
              </bottom>
              <center>
                <GridPane hgap="10.0" vgap="10.0">
                  <children>
                    <Label text="Email:" GridPane.columnIndex="0" GridPane.rowIndex="0" />
                    <TextField fx:id="emailTextField" GridPane.columnIndex="1" GridPane.rowIndex="0">
                      <tooltip>
                        <Tooltip text="Email address" />
                      </tooltip>
                    </TextField>
                    <Label text="Zip code:" GridPane.columnIndex="0" GridPane.rowIndex="1" />
                    <TextField fx:id="zipCodeTextField" GridPane.columnIndex="1" GridPane.rowIndex="1" />
                  </children>
                  <columnConstraints>
                    <ColumnConstraints halignment="RIGHT" hgrow="NEVER" />
                    <ColumnConstraints halignment="LEFT" hgrow="ALWAYS" />
                  </columnConstraints>
                  <padding>
                    <Insets bottom="10.0" left="10.0" right="10.0" top="10.0" />
                  </padding>
                  <BorderPane.margin>
                    <Insets />
                  </BorderPane.margin>
                </GridPane>
              </center>
              <top>
                <TitledPane fx:id="contactTabErrorList" animated="false" expanded="false">
                  <content>
                    <VBox fx:id="contactTabErrorMessages" spacing="5.0" />
                  </content>
                </TitledPane>
              </top>
            </BorderPane>
          </content>
        </Tab>
        <Tab fx:id="confirmationTab" text="Confirmation">
          <content>
            <BorderPane>
              <center>
                <WebView fx:id="browser" />
              </center>
              <top>
                <Label text="Thanks. You may now see the discussion." BorderPane.alignment="CENTER" />
              </top>
            </BorderPane>
          </content>
        </Tab>
      </tabs>
    </TabPane>
  </center>
</BorderPane>

tabvalidation.TabValidationExample.java

package tabvalidation;
	
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.stage.Stage;
import javafx.scene.Parent;
import javafx.scene.Scene;


public class TabValidationExample extends Application {
	@Override
	public void start(Stage primaryStage) {
		try {
			Parent root = FXMLLoader.load(getClass().getResource("TabValidation.fxml"));
			Scene scene = new Scene(root, 800, 600);
			scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
			primaryStage.setScene(scene);
			primaryStage.show();
		} catch(Exception e) {
			e.printStackTrace();
		}
	}
	
	public static void main(String[] args) {
		launch(args);
	}
}

tabvlidation.Controller.java

package tabvalidation;

import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.regex.Pattern;
import java.util.stream.Collectors;

import javafx.beans.InvalidationListener;
import javafx.beans.binding.Bindings;
import javafx.beans.binding.BooleanBinding;
import javafx.beans.binding.ListBinding;
import javafx.beans.binding.LongBinding;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.css.PseudoClass;
import javafx.fxml.FXML;
import javafx.scene.Node;
import javafx.scene.control.Label;
import javafx.scene.control.Tab;
import javafx.scene.control.TabPane;
import javafx.scene.control.TextField;
import javafx.scene.control.TitledPane;
import javafx.scene.control.Tooltip;
import javafx.scene.layout.Pane;
import javafx.scene.web.WebView;

public class Controller {
	@FXML
	private TextField firstNameTextField ;
	@FXML
	private TextField lastNameTextField ;
	@FXML
	private TextField emailTextField ;
	@FXML
	private TextField zipCodeTextField ;
	@FXML
	private Tab nameTab ;
	@FXML
	private Tab contactTab ;
	@FXML
	private Tab confirmationTab ;
	@FXML
	private TabPane tabPane ;
	@FXML
	private TitledPane nameTabErrorList ;
	@FXML
	private Pane nameTabErrorMessages ;
	@FXML
	private TitledPane contactTabErrorList ;
	@FXML
	private Pane contactTabErrorMessages ;
	@FXML
	private WebView browser ;
	@FXML
	private Label nameTabErrorInstructions ;
	@FXML
	private Label contactTabErrorInstructions ;
	
	public void initialize() {
		// Bit of a hack. Probably need a ValidationBinding extends BooleanBinding with a message property:
		Map<BooleanBinding, String> messages = new HashMap<>();

		tabPane.getSelectionModel().select(nameTab);
		BooleanBinding firstNameInvalid = emptyTextFieldBinding(firstNameTextField, "First Name is required", messages);
		BooleanBinding lastNameInvalid = emptyTextFieldBinding(lastNameTextField, "Last Name is required", messages);
		final Pattern emailPattern = Pattern.compile("[a-zA-Z_][a-zA-Z0-9_]*@[a-zA-Z][a-zA-Z0-9_]+(\\.[a-zA-Z][a-zA-Z0-9_]*)+");
		BooleanBinding emailInvalid = patternTextFieldBinding(emailTextField, emailPattern, "You must enter a valid email", messages);
		final Pattern zipPattern = Pattern.compile("[0-9]{5}");
		BooleanBinding zipInvalid = patternTextFieldBinding(zipCodeTextField, zipPattern, "You must enter a 5-digit zip code", messages);
		
		BooleanBinding[] nameTabBindings = { firstNameInvalid, lastNameInvalid } ;
		BooleanBinding[] contactTabBindings = { emailInvalid, zipInvalid } ;
		
		BooleanBinding nameTabInvalid = any(nameTabBindings);
		BooleanBinding contactTabInvalid = any(contactTabBindings);
		
		contactTab.disableProperty().bind(nameTabInvalid);
		confirmationTab.disableProperty().bind(nameTabInvalid.or(contactTabInvalid));
		
		nameTabErrorInstructions.visibleProperty().bind(nameTabInvalid);
		contactTabErrorInstructions.visibleProperty().bind(contactTabInvalid);
		
		bindMessageLabels(nameTabBindings, nameTabErrorMessages.getChildren(), messages);
		
		final LongBinding nameTabErrorCount = count(nameTabBindings);
		nameTabErrorList.textProperty().bind(Bindings.format("%d %s on this page", nameTabErrorCount,
				Bindings.when(nameTabErrorCount.isEqualTo(1)).then("error").otherwise("errors")));
		
		bindMessageLabels(contactTabBindings, contactTabErrorMessages.getChildren(), messages);
		
		final LongBinding contactTabErrorCount = count(contactTabBindings);
		contactTabErrorList.textProperty().bind(Bindings.format("%d %s on this page", contactTabErrorCount,
				Bindings.when(contactTabErrorCount.isEqualTo(1)).then("error").otherwise("errors")));
		
		browser.getEngine().load("http://stackoverflow.com/questions/22772364/javafx-prevent-selection-of-a-different-tab-if-the-data-validation-of-the-selec/");
	}

	private void bindMessageLabels(BooleanBinding[] validationBindings, List<Node> labelList, Map<BooleanBinding, String> messages) {
		ListBinding<Node> nodeListBinding = new ListBinding<Node>() {
			
			{ 
				// calling bind(...) here won't work, neither will using WeakInvalidationListeners. Not sure why....
				InvalidationListener invalidationListener = obs -> invalidate();
				Arrays.stream(validationBindings).forEach(binding -> 
					binding.addListener(invalidationListener));
			}

			@Override
			protected ObservableList<Node> computeValue() {
				return FXCollections.observableList(
					Arrays.stream(validationBindings)
						.filter(BooleanBinding::get)
						.map(messages::get).map(Label::new)
						.collect(Collectors.toList())
				);
			}
		};
		
		Bindings.bindContent(labelList, nodeListBinding);
	}
	
	private BooleanBinding emptyTextFieldBinding(TextField textField, String message, Map<BooleanBinding, String> messages) {
		BooleanBinding binding = Bindings.createBooleanBinding(() -> 
			textField.getText().trim().isEmpty(), textField.textProperty());
		configureTextFieldBinding(binding, textField, message, messages);
		return binding ;
	}
	
	private BooleanBinding patternTextFieldBinding(TextField textField, Pattern pattern, String message, Map<BooleanBinding, String> messages) {
		BooleanBinding binding = Bindings.createBooleanBinding(() -> 
			!pattern.matcher(textField.getText()).matches(), textField.textProperty());
		configureTextFieldBinding(binding, textField, message, messages);
		return binding ;
	}
	
	private void configureTextFieldBinding(BooleanBinding binding, TextField textField, String message, Map<BooleanBinding, String> messages) {
		messages.put(binding, message);
		if (textField.getTooltip() == null) {
			textField.setTooltip(new Tooltip());
		}
		String tooltipText = textField.getTooltip().getText();
		binding.addListener((obs, oldValue, newValue) -> {
			updateTextFieldValidationStatus(textField, tooltipText, newValue, message);
		});
		updateTextFieldValidationStatus(textField, tooltipText, binding.get(), message);
	}
	
	private BooleanBinding any(BooleanBinding[] bindings) {
		return Bindings.createBooleanBinding(() -> 
			Arrays.stream(bindings).anyMatch(BooleanBinding::get), bindings);
	}
	
	private LongBinding count(BooleanBinding[] bindings) {
		return Bindings.createLongBinding(() -> 
			Arrays.stream(bindings).filter(BooleanBinding::get).collect(Collectors.counting()), bindings);
	}

	private void updateTextFieldValidationStatus(TextField textField,
			String defaultTooltipText, boolean invalid, String message) {
		textField.pseudoClassStateChanged(PseudoClass.getPseudoClass("validation-error"), invalid);
		String tooltipText ;
		if (invalid) {
			tooltipText = message;
		} else {
			tooltipText = defaultTooltipText;
		}
		if (tooltipText == null || tooltipText.isEmpty()) {
			textField.setTooltip(null);
		} else {
			Tooltip tooltip = textField.getTooltip();
			if (tooltip == null) {
				textField.setTooltip(new Tooltip(tooltipText));
			} else {
				tooltip.setText(tooltipText);
			}
		}
	}

}