MeetupEvent.java

import java.util.ArrayList;

public class MeetupEvent {
  private String title;
  private int limit;
  private ArrayList<String> attendees;

  public MeetupEvent(String title, int limit) {
    this.title = title;
    this.limit = limit;
    this.attendees = new ArrayList<String>();
  }

  public void register(String member) throws Exception {
    if (this.attendees.size() < this.limit) {
      this.attendees.add(member);
    } else {
      throw new Exception("ended");
    }
  }

  public static void main(String[] args) throws Exception {
    MeetupEvent event = new MeetupEvent("Ethereum Meetup Talk", 40);
    event.register("Yuren Ju");
  }
}