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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: 19848

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.

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Campbell Ritchie

Joined: Oct 13, 2005
Posts: 40476
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.

subject: Switching order for equals operator