ClassNotFound With URLClassLoader

Question

I currently have the following directory tree structure:

CLASSES -> ClassOne ->package -> my ->App.class

I would like to load the App.class from my local drive. I looked around, particularly stackoverflow, and most seem to suggest that I should use the URLClassLoader.

In order to do this, I used this following code:

However, I get a ClassNotFoundError. Can anybody help me please.

 String url = "file://" + classOneFolder.getAbsolutePath(); //Where classesFolder is a File representing the ClassOne directory URL[] urls = {new URL(url)}; urlClassLoader = URLClassLoader.newInstance(urls); //class loader needs the fully classified class name. Therefore: Class appClass = urlClassLoader.loadClass("package.my.App");

Reboot · Accepted Answer · 2014-02-16 14:47:48Z

1

I would suggest you use classOneFolder.toURI().toURL() instead of building the URL yourself as a String and then recreate a URL from it. On some systems (like Windows) you need to add another slash in front on the absolute filename for a valid URL. Using File.toURI().toURL() should always build a correct URL.

edited Feb 16, 2014 at 14:47

answered Feb 16, 2014 at 14:28

Reboot

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3 Comments

Goaler444 Over a year ago

I was going to take that approach, but my IDE is telling me that the method is deprecated

Reboot Over a year ago

Yes, in Java 6 File.toURL() is deprecated. But the JavaDoc was also updated and suggests to use FILE.toURI().toURL() instead. I'll update the answer.

Goaler444 Over a year ago

Thanks, it found it now

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