Java Enum instances are singletons. This seems to be not clearly documented by Sun (at least I found it difficult to find). But it’s the case.

What this means is that it’s possible to compare enumerated types by identity, which is cool for readability. (And it means that the switch statement works.)

You don’t have to write this:

if (PurchaseState.complete.equals(anItem.getPurchaseState()) { ...

You can write:

if (anItem.getPurchaseState() == PurchaseState.complete) { ...

This is documented here in the “discussion” section.

This entry was posted on Thursday, September 6th, 2007 at 2:03 pm and is filed under Java. You can subscribe to Adrian's blog. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.