The number of times I've implemented something by convention due to the lack of this construct... One common use case is that I like "value objects" -- an AccountId class vs. just a String or an Integer. I usually implement them using some sort of internment internally -- WeakHashmap, Guava Interner, etc. When reading from a wire format and using value objects, one must presume the existence of a fromString(String key), fromInt, etc. method. I'd love to state explicitly that all ValueObjects have particular, generic-ified static constructors. Much cleaner. And, it avoids the cliche Java programmer shame of implementing AbstractValueObjectFactory, etc. Some static state, if isolated and properly managed, makes life easier.