I am missing Rectangle.class I'm not sure if this is a typo. Did you mean Rectangle1.class?
If not, then perhaps Rectangle.class isn't in the JAR because you didn't instruct the jar program to include it, as you instructed it to include Rectangle1.class.
If it is a typo, then are you sure that the Rectangle1.class is in the same working directory that you used when running the jar program?
I would also like to know how to run a jar file Take a look at
the Creating an Executable JAR File thread.