Finding the declaring class of a _Jv_Field

Sun Oct 29 14:29:00 GMT 2000

Hi,
On Sun, Oct 29, 2000 at 02:52:20PM -0700, Tom Tromey wrote:
>> Wouldn't we really want to do `final' checking in the bytecode
> verifier? Ok, we don't have a verifier, so interpret.cc is the
> logical choice. But in the long term we'd want to move this check to
> the verifier, right?
If I read the JVM spec right then a final field can actually be assigned
a value multiple times if it is done in the class that declares the field.
But you can never change the value of a final field from another class.
The JSL says that you cannot assign a final field a value twice, but
the JVM spec has no such restriction for byte code. Strange but true!
Try compiling the following with gcj -C (which current has a bug that it
does generate code to change the final field twice) and try running it
with any java interpreter. I haven't found any that would not just print
1 and 2.
public class TestFinal {
 final static Integer i = new Integer(1);
 public static void main(String[] args) {
 System.out.println(i);
 i = new Integer(2);
 System.out.println(i);
 }
}
(Writing code that changes i from another class should throw an exception
though.)
 
> Mark> But after calling _Jv_ResolvePoolEntry I only have a _Jv_Field
> Mark> and I cannot figure out how to get the declaring class for
> Mark> it. How is that done?
>> _Jv_Field fld;
> Class k = fld.getClass ();
>> Or am I missing something?
I thought that gave you the type of the field. I need the class in which
the field is declared. But it might be that I am missing something myself.
Cheers,
Mark