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Switching order for equals operator

Brian Schotky

Joined: Dec 07, 2009
Posts: 1
Hi all,

I've seen in several places that a way to avoid null pointer exceptions is to switch the order of the equals operator. For example, using

Instead of:

Although this seems like a good idea, doesn't this make it harder to debug down the line if you run into problems? Isn't is basically hiding the fact that you have a NPE where you shouldn't?

Just curious what your thoughts were.

Rob Spoor

Joined: Oct 27, 2005
Posts: 19911

In my opinion, you should only write this code if otherwise you would have written In other words, if you already intended to have the null check in place.

How To Ask Questions How To Answer Questions
Campbell Ritchie

Joined: Oct 13, 2005
Posts: 41098
If there is any chance of "dog" being null, then dog.equals("Fido") will throw an Exception and "Fido".equals(dog) will not throw an Exception.
Patricia Samuel
Ranch Hand

Joined: Sep 12, 2007
Posts: 300
General Practice is this only that Rob has suggested.

I agree. Here's the link:
subject: Switching order for equals operator