code: @Override
      public CharSequence subSequence(int start, int end)
      {
          StringBuilder sb = new StringBuilder();
          for (int ii=start;ii<end;ii++)
          {
              sb.append((char)getAt(ii));
          }
          return sb.toString();
      }
docs: Note that implementation uses StringBuilder to create String as CharSequence.
  @param start
  @param end
  @return