Hi, I've done a bit of Processing in Eclipse, but I'm running into a problem I haven't encountered before. I can run the sketch as an Applet, but when I run as Java Application, I get the following error:

Exception in thread "main" java.lang.RuntimeException: java.lang.ClassNotFoundException: DataVizMain
    at processing.core.PApplet.main(PApplet.java:7254)
    at arc_segments.DataVizMain.main(DataVizMain.java:16)
Caused by: java.lang.ClassNotFoundException: DataVizMain
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
    at processing.core.PApplet.main(PApplet.java:7251)
    ... 1 more

Everything was working as both Applet and Application until I made a new version of the project by copying and pasting it in the Package Explorer. After I did this, both versions started giving the above error. After deleting the newer version, I'm STILL getting the error. The project directory structure is as follows:

data_viz_integration_02
   src
      arc_segments
         ArcSegment.java
         DataVizMain.java
   JRE System Library
   Referenced Libraries
   core.jar

The first few lines of my code are here:

package arc_segments;
import processing.core.*;

public class DataVizMain extends PApplet {
   
    public static void main(String args[]) {
        PApplet.main(new String[] { "--present", "DataVizMain" });
      }

   ...

}

Given when this error started appearing (right after I copied the project), I assume it is something really basic that has to do with the Eclipse project directory structure, but I'm just not familiar enough with it to understand what I did wrong. Any help much appreciated, thanks.