Reflection - How to provide qualified path to class?

Question

Hello folks,
I am writing the application in which user will be able examine any java class at any mapped drive at his PC.
The snipplet is as follows:
import java.lang.reflect.*;
public class ClassInfo {
public static void main( String[] args ) throws Exception {
Class theClass = Class.forName(args[0]);
System.out.println("Class Name: " + theClass.getName());
//Other methods go here
(In GUI application I will provide a FileChooser, of course.)
It works perfectly well as long as the class I want to examine is in the same folder. Example below.
C:\MyFolder>java ClassInfo MyClass
Class Name: MyClass
But when I try to provide the full path to the class outside of that folder - it did not work at all. I am getting ClassNotFound exception. I tried every possible way, such as "C:\\myFolder2\\myClass2� and
"myFolder2.myClass2", etc.
Does someone know how to circumvent this obstacle?
Many thanks at advance.
Vlad

Answer 1

Thank you very much, guys, for your responses. I figured it out. Hopefully, my code will be useful for someone else.
The only limitation is: In the current version it does not handles packages, in other worlds, if the class is a part of a package, such as
package hello;
public class HelloFromHell{
//the rest of the class
I am getting error messge:
Exception in thread "main" java.lang.NoClassDefFoundError: HelloFromHell (wrong name: hello/HelloFromHell) It expects to find the class name in the directory named "hello", which is a package name.
Vlad
import java.io.*;
import java.lang.reflect.*;
import java.net.*;
import javax.swing.*;
public class ClassInfo {
static void displayClassInfo(File file) {
//Get Directory info
File directory = file.getParentFile();
//Get Class name without ".class" ext
String className = file.getName().substring(0,file.getName().length() -".class".length());
try {
//Create the URLClassLoader
URL[] theURL = {directory.toURL()};
URLClassLoader loader1 = new URLClassLoader(theURL);
//Pass class name loader to the forName method
Class theClass = Class.forName(className, true, loader1);
System.out.println("Directory: " + directory.toURL());
System.out.println("Class: " + theClass.getName());
Method[] theMethods = theClass.getDeclaredMethods();
System.out.println("Methods:");
System.out.println("-------");
for (int i = 0; i < theMethods.length; i++) {
System.out.println("Name: " + theMethods.getName());
System.out.println();
//Other reflection methods go here as needed
catch (ClassNotFoundException cnfe) {
System.err.println(cnfe);
System.err.flush();
catch (java.net.MalformedURLException mue) {
System.err.println(mue);
System.err.flush();
//Helper method to prevent user from selecting anything but java classes
static boolean isClass(String fileName) {
if (fileName.endsWith(".class")) {
return true;
return false;
//Method to call JFileChooser dialog thus preventing users from typing
public static void main(String[] args) {
// display a file dialog to the user for file selection
JFileChooser fileChooser = new JFileChooser(System.getProperty("user.dir"));
if (JFileChooser.APPROVE_OPTION == fileChooser.showOpenDialog(new JFrame())) {
if ( (fileChooser.getSelectedFile().getName() != null) &&
(isClass(fileChooser.getSelectedFile().getName()))) {
displayClassInfo(fileChooser.getSelectedFile());
else {
//Handle errors gracefully
System.out.println("No file was selected or file is not a java class.");
System.exit(0);