/* StringSorterLenLexico.java
** An instance of this class has methods (inherited from its parent)
** by which to sort an array (or a segment thereof) of Strings into
** ascending order.  It supplies the body of isLessThan() for the
** purpose of defining/implementing an ordering on strings.  Here,
** that is "length-lexicographic" ordering, which says that string
** s1 is less than string s2 iff either 
** (1) s1 is shorter than s2 (in length), or
** (2) s1 and s2 are of the same length and s1 is less than s2 based
**     on lexicographic ordering.
*/

public class StringSorterLenLexico extends StringSorter {

   /* Returns true iff s1 < s2 according to Length-Lexicographic
   ** ordering, which is to say that either
   ** (1) s1.length() < s2.length() or
   ** (2) s1.length() = s2.length and s1.compareTo(s2) < 0
   */
   @Override
   protected boolean isLessThan(String s1, String s2) {
      final int lengthDiff = s1.length() - s2.length();
      if (lengthDiff < 0) 
         { return true; }       // s1 is shorter than s2, so s1 < s2
      else if (lengthDiff > 0) 
         { return false; }      // s1 is longer than s2, so s1 > s2
      else 
         { return s1.compareTo(s2) < 0; }  // s1 and s2 are of same length, so
   }                                       // revert to lexicographic order

}