/*
   *  listTermDictionary displays the term dictionary for a field.
   */
  static void listTermDictionary(IndexReader reader, String fieldName) throws IOException {

    System.out.println("\nTerm Dictionary:  field " + fieldName);

    /*
      Grant says:
      MultiFields.getTerms(IndexReader, fieldName)
    */

    Terms terms = MultiFields.getTerms(reader, fieldName);

    if ((terms == null) || (terms.size() == -1))
      System.out.println("    The term dictionary is empty.");
    else {
      System.out.println("    Vocabulary size: " + terms.size() + " terms");

      TermsEnum ithTerm = terms.iterator(null);

      /*
       *  Iterate over the terms in this document.
       *  Information about a term's occurrences (tf and
       *  positions) is accessed via the indexing API, which
       *  returns inverted lists that describe (only) the
       *  current document.
       */
      while (ithTerm.next() != null) {
        System.out.format(
            "      %-30s %d %d\n",
            ithTerm.term().utf8ToString(), ithTerm.docFreq(), ithTerm.totalTermFreq());
      }
      ;
    }
    ;
  }
  /*
   *  Utility function to display a term vector.
   */
  static void termVectorDisplay(Terms terms) throws IOException {

    if ((terms == null) || (terms.size() == -1)) System.out.println("    The field is not stored.");
    else {
      /*
       *  The terms for this field are stored.
       */
      System.out.println("    Vocabulary size: " + terms.size() + " terms");

      TermsEnum ithTerm = terms.iterator(null);

      /*
       *  Iterate over the terms in this document.
       *  Information about a term's occurrences (tf and
       *  positions) is accessed via the indexing API, which
       *  returns inverted lists that describe (only) the
       *  current document.
       */
      while (ithTerm.next() != null) {
        System.out.format(
            "      %10d %-20s %d ",
            ithTerm.ord(), ithTerm.term().utf8ToString(), ithTerm.totalTermFreq());

        DocsAndPositionsEnum currDoc = ithTerm.docsAndPositions(null, null);
        currDoc.nextDoc();

        for (int jthPosition = 0; jthPosition < ithTerm.totalTermFreq(); jthPosition++)
          System.out.print(currDoc.nextPosition() + " ");

        System.out.println();
      }
      ;
    }
    ;
  }