public class Test {
  public static void main(String[] args) {
    String arg = "";
    if (args.length > 0) arg = args[0];

    java.util.HashSet<Human> humanSet = new java.util.HashSet<Human>();

    humanSet.add(new Human(""));
    humanSet.add(new Human(""));
    humanSet.add(new Human(""));
    humanSet.add(new Human(""));
    humanSet.add(new Human("Bull"));
    humanSet.add(new Human("Bull"));
    humanSet.add(new Human("Bull"));
    humanSet.add(new Human("Smith"));
    humanSet.add(new Human("Smith"));
    humanSet.add(new Human("Will"));
    String msg = "Before: " + humanSet.size();

    java.util.Iterator<Human> iterator = humanSet.iterator();
    while (iterator.hasNext()) if (arg.equals(iterator.next().getName())) iterator.remove();

    System.out.println(msg + ", after: " + humanSet.size());
  }
}

class Human {
  private final String name;
  Human(String arg) { name = arg; }
  String getName() { return name; }
}