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CodeSOD: Not for Nullthing

The Daily WTF
2 months 1 week ago

Today's anonymous submitter sends us some code that just makes your mind go… blank when you look at it.

public static boolean isNull(String value) { return StringUtils.isBlank(value); }

StringUtils.isBlank comes from the Apache Commons library. It's a helper function for Java which returns true if a string is, well, blank. "Blank" in this case is: empty, null, or only whitespace. So it's important to note that isBlank may return true on a null, but it isn't truly a null-check, so wrapping it in isNull is just confusing.

But imagine I've got another problem. Let's say I have a database that's been poorly normalized and maintained. And so I have a bunch of fields that maybe are null, but some also maybe contain the string "null". What am I going to do then? I need another function.

public static boolean isNullAndNull(String value) { return isNull(value) && "null".equalsIgnoreCase(value); }

Ah yes, isNullAndNull, the clearest and easiest name I could imagine for this. It tells me exactly what the function is checking: is it null, and is it also null? We add a second check to our isNull call- we check if the input value matches the string "null". Except we're &&ing the conditions together. So this function will always return false. It can't both be blank and contain the string "null".

Which means Jennifer Null, who is a real person, can breathe easy. This version of a null check won't think she's nothing.

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Remy Porter