Main.java

import java.util.*;

public class Main {
    public static void main(String[] args) {
        FunctionalSet<Integer> s = new FunctionalSet<>();
        String line;
        do {
            line = SimpleIO.getString("Enter 'add i', 'remove i', 'min', or 'exit'!");
            String[] words = line.split(" ");
            try {
                switch (words[0]) {
                case "exit": break;
                case "add":
                    s.add(Integer.parseInt(words[1]));
                    System.out.println(s);
                    break;
                case "remove":
                    s.remove(Integer.parseInt(words[1]));
                    System.out.println(s);
                    break;
                case "min":
                    System.out.println(s.min(Comparator.<Integer>naturalOrder()));
                    break;
                default:
                    System.out.println("Unknown command.");
                }
            } catch (MinimumOfEmptySetException e) {
                System.out.println("The minimum of the empty set is not defined!");
            } catch (NumberFormatException e) {
                System.out.println("Failed to parse the number to add/remove.");
            }
        } while (!"exit".equals(line));
    }
}