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obj == null OR null == obj, which is better?

Mohit Jain
Ranch Hand

Joined: Jun 04, 2007
Posts: 74
While comparing a reference for null value, out of following two ways which way is better??

obj == null OR null == obj

They say it doesnt make difference when this condition is used all alone, but its better to put null on left side when two conditions are concatenated using && or || like -

null == obj && <some condition>

Please suggest.

SCJP 5.0, SCWCD in progress
Christophe Verré

Joined: Nov 24, 2005
Posts: 14688

Please be patient.

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Henry Wong

Joined: Sep 28, 2004
Posts: 20531

For C/C++, if you accidentally used "=" (assignment) instead of "==" (comparison), it will assign the value, and still have a valie that can be used in the condition. Thia made for some really obscure bugs. Reversing it fixed the problem, as you can assign a variable to a literal (null).

For Java, it doesn't matter as you can't use null as a boolean (implicitedly).

[ April 25, 2008: Message edited by: Henry Wong ]

Books: Java Threads, 3rd Edition, Jini in a Nutshell, and Java Gems (contributor)
I agree. Here's the link:
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