I'm not suggesting that .equals() should be implemented by 2 inter() operations followed by a reference comparison. But that the implementation check whether t

I'm not suggesting that .equals() should be implemented by 2 inter() operations followed by a reference comparison. But that the implementation check whether the pair of Strings happened to be already .intern()ed, and then use the short circuit of a reference comparison. A programmer could then decide to intern _some_ non-constant Strings in their application if it made sense (i.e. they were frequently used in comparisons or as hash keys). And I don't think you can't run out of permgen as the String pool is a fixed size - unless I am misreading that section of the article. However now that I've thought about a bit more, I think the flaw in the idea is unrelated to your points but that currently it's not cheap to determine if a particular String is interned. The StringTable implementation would have to be changed otherwise it would require adding storage overhead to every String which would not be acceptable. This is also probably why .hashCode() doesn't memoize it's results.