import java.util.*;

public class TreeMapByLength
{
	public static void main (String[ ] args) 
    	{
		TreeMap<String, Integer> wordLengths =
				new TreeMap<String, Integer>(new ByLength());

		wordLengths.put ("serendipity", new Integer(11));
      		wordLengths.put ("always", new Integer(6));
      		wordLengths.put ("serenity", new Integer(8));
     		wordLengths.put ("utopia", new Integer(6));

      		System.out.println (wordLengths);
	} // method main

} // class TreeMapByLength

class ByLength implements Comparator<String> 
{
	/** 
 	 *  Compares two specified String objects lexicographically if they have the 
 	 *  same length, and otherwise returns the difference in their lengths.
 	 *
 	 *  @param s1 - one of the specified String objects.
 	 *  @param s2 - the other specified String object.
 	 *
 	 *  @return s1.compareTo (s2) if s1 and s2 have the same length; 
  	 *                otherwise, return s1.length() - s2.length(). 
 	 *
 	 */	
	public int compare (String s1, String s2) 
	{
		int len1 = s1.length(),
  	            len2 = s2.length();
		if (len1 == len2)
			return s1.compareTo (s2);
        	return len1 - len2;
    	} // method compare

} // class ByLength