Confirmation on files without class or interface definitions

[Trav Smith]

Hi all,
I just wanted to check if both of these assertions are true:
"A Java file without any class or interface definitions can also be compiled."
"If an import statement is present, it must appear before any class or interface definitions."
Thanks very much for your time,
Trav

[Lei Wu]

"A Java file without any class or interface definitions can also be compiled."

From JLS 7.3:
CompilationUnit:
PackageDeclaration(opt) ImportDeclarations(opt) TypeDeclarations(opt)

As above, since all the parts of a CompilationUnit in Java is optional, I think it is right to say so. Actually, JDK1.4.1 does treat an empty file as a valid compilation unit. You can even write like this:

package mypackage;
import java.lang.*;

It's also a valid compilation unit according to the definition.

"If an import statement is present, it must appear before any class or interface definitions."

Yes. you can see from the above definition that ImportDeclarations must appear before TypeDeclarations.