new TreeSet<String>(comparator) 不带有参数？这是什么意思呃。多谢

import java.util.*; public class TreeSetDemo {          public static void main(String[] args)     {                       Comparator<String> comparator = new CustomComparator1<String>();                  Set<String> set =   new TreeSet<String>(comparator);                          set.add("justin");                set.add("caterpillar");                  set.add("momor");                                 for(String name : set)         {                      System.out.print(name + " ");                 }                 System.out.println();          }             }

import java.util.Comparator;public class CustomComparator1<T> implements Comparator<T>{                public int compare(T o1, T o2)           {                      if (((T) o1).equals(o2))                             return 0;                      return ((Comparable<T>) o1).compareTo((T) o2) * -1;              }}