Getting 'binary name' of the package of a given class

Question

I needed this for a kind of dynamic class loader, where the binary name of the package of an object was required. What made it more complex is that the classpath of the object is not the local filesystem path, where the java executable was invoked (such as 'bin' in an eclipse project)
I searched the forum, and didn't find a solution that addresses all of these problems. Finally I came up with my own solution, and I'll share it with you (also because there might be some bright minds who can tell me it can be done much simpler (which I hope))
@SuppressWarnings("null")
public static String getPathFromClass(Class< ? > rootClass) throws FileNotFoundException
     String rootPath;
          // These are all the possible directories where the package root
          // exists (relative to where the java executable might be invoked).
          String systemPaths[] = {"bin", "."};
          File root = null;
          for (String systemPath : systemPaths)
               root = new File(systemPath);
               if (root.exists())
                    break;
          if (!root.exists() || !root.isDirectory())
               throw new FileNotFoundException("No package root found");
          rootPath = root.getAbsolutePath();
     String localPath;
     try
          localPath = new File(rootClass.getResource(".").toURI()).getPath();
     catch (URISyntaxException e)
          // Should never happen; Hack to prevent unjust error.
          localPath = "";
     if (!localPath.startsWith(rootPath))
          // What's going on ??
          throw new FileNotFoundException("Class' local path not inside package root");
     return localPath.substring(rootPath.length() + 1).replace(File.separatorChar, '.');
}Example:
main class is in c:\projects\test\bin\test\mj\foo\Main.class (package declaration sais "test.mj.foo".)
java.exe is executed from c:\projects\test\
calling this method with an instance of the Main class returns: "test.mj.foo".

Answer 1

As far as I can tell it just returns the package root (such as "c:\projects\test\bin"), but because of that, it does greatly simplify the first part of my function. Thanks.
String rootPath = new File(rootClass.getProtectionDomain().getCodeSource().getLocation().toURI()).getPath();
String localPath;
...A binary name (as mentioned in the Java Language Specification) is a representation of a fully qualified java class, such as "java.lang.String". A "binary name of a package" as I mentioned is just my way of meaning anything like "java.lang".