This surpised me. The following program does not throw a NullPointerException
public class StaticFieldThroughNull {
public static void main(String[] args) {
Double d = null;
System.out.println(d.MAX_VALUE);
}
}
This really is supposed to work this way. See the JLS.
Check out the example at the end of the section of the spec linked above. Its even more surprising than mine, because it uses a method that returns null rather than a null variable.
This bug was fixed in 1.4.1...
http://developer.java.sun.com/developer/bugParade/bugs/4449316.html
From my reading of the but report cited above, it sounds like it is a related bug, and that they almost changed the behavior I pointed out, but then realized that they should not chnage it.
It would be a bug if the code I included in the blog entry did actually throw a NullPointerException. I'm not sure what the behavior was prior to Java 1.4.1.
What I forgot to make clear in my post was that since we're examining a static field, it is only the type of the variable that matters, not its value. That is why the static field can be accessed through the null value.
FWIW, I'd be having a chat to any of your developers that routinely access static members through instance variables, null or not. They're static for a reason :-)