///////    SortKey.java    ///////
import java.util.StringTokenizer;

public class SortKey
{  public SortKey(int pos, String dlm)
   {  delim = dlm;           // delimiter string
      position = pos;        // key position
   }
   public SortKey(int pos) { position = pos; }
   public SortKey() { }

// compare a and b by key, returns -1, 0, 1
   public int cmp(String a, String b)
   {   String ka = key(a);
       String kb = key(b);
       if ( ka == null )
       {   if ( kb == null ) 
              return(0);
           else
              return(-1);
       }
       if ( kb == null ) return(1);
       return ka.compareTo(kb);
   }
// extract key
   public String key(String s)
   {   if ( position == 0 ) return s;
       StringTokenizer st = new StringTokenizer(s, delim);
       String key = null;
       int j = st.countTokens();
       if ( position <= j )
       {   for (j=0; j < position; j++)
              key = st.nextToken();
       }
       return key;
   }
   private String delim = "\t \r";
   private int    position = 0;
}