Daniel Pitts’ Tech Blog

Image this. You develop a Java application that uses only standard Java features. It only uses a hand full of classes, so you just distribute individually. It works great until someone using windows runs your program.

“Why am I getting ‘Exception in thread “main” java.lang.NoClassDefFoundError: FOO (wrong name: Foo)’?”
Remember, Java is case sensitive, but the Windows file system is *not*.

public class Foo {
  public static void main(String...args) {
    new FOO();
  }
}

class FOO {
  public FOO() {
    System.out.println("Works like a charm.");
  }
}

When you compile this on Linux, you get “Foo.class” and “FOO.class”, but on Windows, you only get one file. Oops!

So, its always a good idea to follow good convention with regards to capitalization. Use CamelCase, and treat abbreviations as words. Use XmlParser rather than XMLParser. Note that some of the standard Java API doesn’t do that (URL for instance).