Catching OutOfMemoryError

Question

Is there any point catching an out of memory error (java.lang.OutOfMemoryError) in Java?

Answer 1

Yes. Here are a few examples where it could make sense:

• if you want to handle it by gracefully closing your program
• if you want to display the problem to the user or log the error
• depending on your design, you might even be able to clear up memory and restore a working state

However, note that normally (unless you're at a spot where you'll be allocating tons of memory at once), you probably wouldn't specifically catch OutOfMemoryError for these cases, but rather do a catch Throwable all the way at the top in your main entry point.

Answer 2

The golden rule is to only catch errors that you can handle. If you can do something useful after an OutOfMemory error, then go ahead.

Answer 3

No, catch Exception and RuntimeException, but hardly ever (changed from 'never') Error:

An Error is a subclass of Throwable that indicates serious problems that a reasonable application should not try to catch. Most such errors are abnormal conditions. The ThreadDeath error, though a "normal" condition, is also a subclass of Error because most applications should not try to catch it.

Note:
I'm quoting the official Javadocs here. If you don't agree, tell Oracle, don't shoot the messenger :-)