Is there a way to to detect completion of a java applet so I can inform the user to wait by that time?

I have an applet which first runs a class and then downloads an image. during downloading the class the user can not see any sign of progress unless they notice their connection icon (that two TVs) at the button right of their browser which it is not always "on".

so in brief I need a way for all or some of these:
1. detect the completion of the class.
2. detect if java has failed.
3. detect if the image was not downloaded.

this is the applet. I just delete not related lines of it:

<applet code='ptviewer.class' archive='ptviewer.jar' codebase='' width='300' height='200' >
<param name=file value='images/myImage.jpg'>

and the site: