This is a class for managing input checking/restriction on JavaFX TextFields.

TextFieldManager.java

// <just add your project's package name here if necessary>

import javafx.scene.control.TextField;

// input manager for JavaFX TextFields
public class TextFieldManager {

    // limits text input
    public static void addTextLimit (TextField textField, int limit) {
        // fired by every text property change
        textField.textProperty().addListener((observable, oldValue, newValue) -> {
            if(newValue.length() > limit) {
                System.out.println("Text length limit exceeded!");
                textField.setText(oldValue);
            }
        });
    }

    // makes the text field accept only numeric values
    public static void addNumericInputOnly (TextField textField) {
        textField.textProperty().addListener((observable, oldValue, newValue) -> {
            if (!newValue.matches("\\d*")) {
                textField.setText(newValue.replaceAll("[^\\d]", ""));
            }
        });
    }

    // makes the text field restrict numeric values
    public static void restrictNumericInput (TextField textField) {
        textField.textProperty().addListener((observable, oldValue, newValue) -> {
            textField.setText(newValue.replaceAll("\\d", ""));
        });
    }

    // makes the text field listen only to
    public static void addLetterInputOnly(TextField textField) {
        textField.textProperty().addListener((observable, oldValue, newValue) -> {
            textField.setText(newValue.replaceAll("[\\W\\d]",""));
        });
    }

    // restrict characters given by user through an array
    public static void restrictSpecificCharacters(TextField textField, char[] restrictedChararcters) {
        textField.textProperty().addListener((observable, oldValue, newValue) -> {
            String regex = "";

            for (char w : restrictedChararcters) {
                regex += w;
            }

            textField.setText(newValue.replaceAll("["+regex+"]", ""));

        });
    }
}