What does the question mark mean in GSP/Grails?

Question

I saw this in my generated GSP pages. What does the ? mean?

Answer 1

This is very important feature in Groovy. If the object is null (ie, "phoneInstance" is null) then it's provide "null" value. This feature is called "Safe Navigation Operator". Simply when we use this feature , No need of checking the object("phoneInstance") is null or not.