URLClassLoader not working

Question

I want to load a file in the directory F:/badge-dao/bin/com/badge/dao/impl/ , named BadgeDaoImpl . I am writing and testing the following code.

If I change the directory or the class name, it throws an exception. For the following code, which I suppose should work, it do not throw a classNotFoundException, but rather halts and take the control to EventTable's finally block.

Can you please tell me where I am getting it wrong.

URL[] urls = {new URL("file:/F:/badge-dao/bin/com/badge/dao/impl/")};

ClassLoader parentClassLoader = project.getClass().getClassLoader();

URLClassLoader classLoader = new URLClassLoader(urls, parentClassLoader);

selectedClass = classLoader.loadClass("BadgeDaoImpl");

Answer 1

Package name is a part of full class name, not classpath item, so you need the following:

URL[] urls = {new URL("file:/F:/badge-dao/bin")}; 
...
selectedClass = classLoader.loadClass("com.badge.dao.impl.BadgeDaoImpl"); 

In your original code classloader can find a file named BadgeDaoImpl.class in file:/F:/badge-dao/bin/com/badge/dao/impl/ , but its full class name ( com.badge.dao.impl.BadgeDaoImpl ) doesn't match the requested one ( BadgeDaoImpl ), therefore classloader throws a NoClassDefFoundError . Since you are catching only ClassNotFoundException , it looks like control silently passes to the finally block. When you change folder or class names so that .class file can't be found, ClassNotFoundException is thrown as expected.