Groovy, null, and ‘null’

Groovy will let you call toString() on a null object. The result is the word ‘null’, which might be what you’re expecting if you know the object is null, but probably isn’t what you’re expecting if you don’t.

So if you’re, say, binding a SQL parameter and you forget to check for nulls like you would in Java, and you forget to use a null-safe operator like you should in Groovy, and you get a null value, what happens? Does groovy…

• Throw a NullPointerException like Java?
• Set the field to null?
• Set the field to a blank string?

None of the above. It sets the field to the string ‘null’.

Honestly, I can’t think of any circumstance outside of debugging where I’d want that as the default behavior.

Make sure to use myVariable?.toString() instead of myVariable.toString() for cases like this!