Alex Rivera | Logout

Shortcut "or-assignment" (|=) operator in Java

Asked 2010-03-21T09:06:34.217
96

I have a long set of comparisons to do in Java, and I'd like to know if one or more of them come out as true. The string of comparisons was long and difficult to read, so I broke it up for readability, and automatically went to use a shortcut operator |= rather than negativeValue = negativeValue || boolean.

boolean negativeValue = false;
negativeValue |= (defaultStock < 0);
negativeValue |= (defaultWholesale < 0);
negativeValue |= (defaultRetail < 0);
negativeValue |= (defaultDelivery < 0);

I expect negativeValue to be true if any of the default<something> values are negative. Is this valid? Will it do what I expect? I couldn't see it mentioned on Sun's site or stackoverflow, but Eclipse doesn't seem to have a problem with it and the code compiles and runs.

Similarly, if I wanted to perform several logical intersections, could I use &= instead of &&?

java assignment-operator compound-assignment or-operator
Edit
Report

1 Answer

16

It's not a "shortcut" (or short-circuiting) operator in the way that || and && are (in that they won't evaluate the RHS if they already know the result based on the LHS) but it will do what you want in terms of working.

As an example of the difference, this code will be fine if text is null:

boolean nullOrEmpty = text == null || text.equals("")

whereas this won't:

boolean nullOrEmpty = false;
nullOrEmpty |= text == null;
nullOrEmpty |= text.equals(""); // Throws exception if text is null

(Obviously you could do "".equals(text) for that particular case - I'm just trying to demonstrate the principle.)

answered 2010-03-21T09:12:10.893

Your Answer