Collection Comparison in java pgm

Collection Comparison

import java.util.Collections;

import java.util.Set;

import java.util.TreeSet;

class MainClass

{

 public static void main(String[] args)

  {

      String[] coins = { "Penny", "nickel", "dime",  "Quarter", "dollar" };

      Set set = new TreeSet();

      for (int i = 0; i < coins.length; i++)

         set.add(coins[i]);

      System.out.println(Collections.min(set));

      System.out.println(Collections.min(set,

      String.Case_insensitive_order));

      for(int i=0;i< =10;i++)

         System.out.print(-);

      System.out.println(Collections.max(set));

      System.out.println(Collections.max(set,

      String.Case_insensitive_order));

   }

}