在JavaFX SimpleObjectProperty中禁止null (或返回默认值)

import javafx.beans.property.SimpleObjectProperty;
import javafx.beans.property.adapter.JavaBeanObjectPropertyBuilder;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;

public class Main {
    public static void main(String[] args) {
        NotNullProperty<String> property = new NotNullProperty<>("Default Value");

        property.addListener(new ChangeListener<String>() {
            @Override
            public void changed(ObservableValue<? extends String> observable, String oldValue, String newValue) {
                System.out.println("Property changed: " + newValue);
            }
        });

        property.set("New Value"); // 正常设置新值
        property.set(null); // 抛出NullPointerException异常
    }

    public static class NotNullProperty<T> extends SimpleObjectProperty<T> {
        private T defaultValue;

        public NotNullProperty(T defaultValue) {
            this.defaultValue = defaultValue;
        }

        @Override
        public void set(T newValue) {
            if (newValue == null) {
                throw new NullPointerException("Null value is not allowed");
            }
            super.set(newValue);
        }

        @Override
        public T get() {
            T value = super.get();
            return value != null ? value : defaultValue;
        }
    }
}