package org.kuali.student.ap.coursesearch.controller;
   
   import java.util.*;
   
   public class TokenPairs
   {
       public static List<String> toPairs(List<String> list)
       {
           ArrayList<String> pairs = new ArrayList<String>();
          int a = 0;
          int b = 0;
          int size = list.size();
          while( a < size )
          {
              String result = null;
              if( a == b )
              {
                  result = list.get( a );
                  b++;
              }
              else if( a != b )
              {
                  result = list.get( a ) + " " + list.get( b );
                  a++;
              }
  
              if( b == size )
              {
                  a = b;
              }
  
              pairs.add( result );
          }
  
          return pairs;
      }
  
      public static class LongestFirst implements Comparator<String>
      {
         // First sort by length, then by String's own comparison (ie alpha)
         public int compare( String left, String right )
         {
            int diff = right.length() - left.length();
            if( diff == 0 )
            {
                diff = left.compareTo( right );
            }
            return diff;
         }
      }
  
      public static void sortedLongestFirst( List<String> list )
      {
          Collections.sort(list, new LongestFirst());
      }
  }