..

 File possibleParentPackage =
     classFile.getParentFile();

Andrew T.

You can specify null to defineClass.

Here are a standalone example:

package december;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

public class ClassnameFinder {
    private static byte[] load(String fnm) throws IOException {
        File f = new File(fnm);
        byte[] b = new byte[(int)f.length()];
        InputStream is = new FileInputStream(f);
        is.read(b);
        is.close();
        return b;
    }
    public static String getClassname(String fnm) throws IOException,
ClassNotFoundException {
        ClassnameFinderHelper help = new ClassnameFinderHelper();
        return help.getClassname(load(fnm));
    }
    public static void main(String[] args) throws Exception {
        System.out.println(getClassname("C:\\X.class"));
    }
}

class ClassnameFinderHelper extends ClassLoader {
    public String getClassname(byte[] bc) {
        return defineClass(null, bc, 0, bc.length).getName();
    }
}

Arne

Class loader behavior depends on the class loader implementation. You can
write a class loader to do whatever you want, within the constraints of the
class loader design patterns. Packages are typically anchored to the
directory hierarchy relative to the classpath directory. This is true for
classes lying "loose" in the file system, and for classes in a jar file.
Without the directory structure, you might have a problem.

It might be helpful to look here
(http://java.sun.com/j2se/1.5.0/docs/api/java/lang/ClassLoader.html) and
here (http://java.sun.com/j2se/1.5.0/docs/api/java/net/URLClassLoader.html)
to really understand class loaders. If you cannot find a class loader that
does what you need, you might be able to write one. People often confuse the
behavior of the default class loader with class loaders in general, or with
the Java spec itself.