Originally posted by Jesper Young: str = NULL will not compile.
Unless NULL is defined somewhere, of course, for example as a field.
The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus
To expand on this, remember that Java is case sensitive. So the keyword "null" is not the same as "Null" or "NULL" or any other combination of upper/lowercase. None of these other case variations have any meaning (unless you specifically define them as your own identifier).
"We're kind of on the level of crossword puzzle writers... And no one ever goes to them and gives them an award." ~Joe Strummer sscce.org