Develop a Java program that meets the following requirements:
Assume that you will be implementing Java software to track attendees for a conference: if the guest's identifying information is found, they are allowed to enter. A guest's identifier includes their full name and then an integer to represent their guest category number.
Based on your experience with the hash set and hash map data structures, decide whether to use a hash map or hash set for step 2 for this task for most effective programming.
Briefly explain in code comments on your class your reasoning for the choice.
For example, a guest identifier could be: FrankSmith3992