classloader chain

[Thomas Rochon]

Hi there !
I'm fighting with a problem for a while and now I reached the
point from where I dont have any clue how to solve it.
I'm trying to create a custom classloader and put it into
chain with the default classloader, so if the default (systems)
classloader fails to find a class, this task schould be done
by my stunning custom classloader.
And here's how I try it:

  
public class CustomClassLoader extends ClassLoader {
   public CustomClassLoader(ClassLoader c) {
     super(c);
   }
   // overwriting method from java.lang.ClassLoader
   protected Class findClass(String name) {
     System.out.println("custom loader trying to find class " + name);
     return null;
   }
   // let's test this great class
   public static void main(String[] args) {
     CustomClassLoader cl = 
       new CustomClassLoader(ClassLoader.getSystemClassLoader());
     Class cls = null;
     try {
       cls = Class.forName("java.lang.IdontExist");
     } catch (ClassNotFoundException e) {
       System.out.println("Well - something went wrong!");
     }
   }   
}

What I expected this nice app will do is:
1. calling the default systems classloader to find my not existing class
2. the default systems classloader will fail to find the class and delegate
the request to my fabolous custom classloader by calling findClass
3. The console will show me 'custom loader trying to ...'
4. I will receive a ClassNotFoundException
Step 1 and 4 are doing great. But it seems like step 2 and 3
are missing. I debugged this app and it looks like the systems default
classloader isn't calling my custom classloader!
Does anyone have an idea why my code doesn't work?
I would be very thankful to receive some comments.
Thanx in advance!
- Thomas -
[ May 06, 2004: Message edited by: Thomas Rochon ]