Resource not found.

Ok but if you put your images into a directory "images/" at the root of your JAR it should work.

After I put the images folder at the root I tried:

this.getClass().getClassLoader("images/");

Wavelogy.class.getResourceAsStream("/images/")

They work on Windows but they don't work on Ubuntu 12.1.

One more thing. Let me be clear. This is the correct way to load resources from a Web Start Jar according to Oracle' tutorials: this.getClass().getClassLoader("images/");, other ways of achieving this are just hacks.