Getting fully qualified name from class' byte code

Question

Heya,
In one of my previous postings, I was asking if anybody knows a way how to get fully gualified name (e.g. java.lang.Object) of byte[] representing bytecode of the class.
I found a way how to get it. It's a workaround, but it works.
I mention it here, so that if anybody needs, he/she doesn't need to invent it again.
And if anybody knows better way how to do it, I'm always interested.
here comes the code:
public String getFullClassName(byte[] classByteCode) {
    Class newClass = null;
    try {
        // ClassName can NEVER start with number - this will always fail
        newClass = this.defineClass("1",classByteCode,0,classByteCode.length);
    } catch (NoClassDefFoundError noClassDefErr) {
        String message = noClassDefErr.getMessage(); // '1 (wrong name: com/foo/MyClass)'
        String messagePropolg = "wrong name: ";
        String className = message.substring(message.indexOf(messagePropolg)+messagePropolg.length(),message.length()-")".length());
        className = className.replace('/','.');
        return className;
    } catch (ClassFormatError err) {
        err.printStackTrace();
    if (newClass==null) return null;
    return newClass.getName();// should never get here. it's just to make it compile
}Michal

Answer 1

Heya,
In one of my previous postings, I was asking if
anybody knows a way how to get fully gualified name
(e.g. java.lang.Object) of byte[] representing
bytecode of the class.
Why don't you just read the name?
http://java.sun.com/docs/books/vmspec/2nd-edition/html/ClassFile.doc.html#80959
From the class structure you get field this_class.
You use that to get the pool entry for the CONSTANT_Class_info structure. From that you get the name_index which gives you an entry into the pool for a CONSTANT_Utf8_info (which contains the name)...
http://java.sun.com/docs/books/vmspec/2nd-edition/html/ClassFile.doc.html#7963