Mis-Using Abstract for Static Classes

Recently came across this construction in the code we have at work.

	public abstract class StringUtilities
	{
	public static void stuff()
	{
	// do stuff
	}
	}

view raw StringUtilities.java hosted with ❤ by GitHub

Now, some notes:

• nowhere was a subclass defined to implement the 'abstract methods' in StringUtilities.
• as a matter of fact, there were no 'abstract methods'.
• all other methods were defined 'static'

It seemed a weird way to defeat instantiation (badly, by the way, as a person could simply subclass the thing and instantiate that).

Proper defeating of instantiation is done by means of a private constructor.

	public class StringUtilities
	{
	/**
	* Defeat instantiation.
	*/
	private StringUtilities()
	{
	}
	public static void stuff()
	{
	// do stuff
	}
	}

view raw StringUtilities.java hosted with ❤ by GitHub

But, if what you need is a Singleton, perhaps it's better to just define a single ENUM.

Nobody could quite explain to me in which cases the first example would be a "Good Idea"™.