如何显示单例对象的属性？

public class Singleton {
   private static Singleton instance;
   private String property;

   private Singleton() {
      property = "This is a property of Singleton object";
   }

   public static Singleton getInstance() {
      if (instance == null) {
         instance = new Singleton();
      }
      return instance;
   }

   public String getProperty() {
      return property;
   }
}

public class Main {
   public static void main(String[] args) {
      Singleton singleton = Singleton.getInstance();
      System.out.println(singleton.getProperty());
   }
}