SE450: What if you want class names to be hidden from clients? [43/47]

What if class names are not stable? (I have the shapes Circle and Square, but may generalize later to allow ellipses and rectangles.)

Consider using a static factory:

• Make object interfaces public.
• Make object classes package-private.
• Provide a public static class (the factory), which produce instances of the object interfaces.
• Other packages use the factory, not the constructors.
• Factory methods can have parameters to initialize the objects.