Hi,
Welcome to JavaRanch!
To run a class, the class needs to have a method declared like this:
public static void main(
String[] args)
Does "Party" have such a method? If not, it's not intended to be run as a standalone application; perhaps it's part of a larger example, which you would run using some other class, or perhaps it's just meant as a partial example, not intended for you to run.