code: public static int getIndexOf (@Nullable final String sText,
                                  @Nonnegative final int nFromIndex,
                                  @Nullable final String sSearch)
    {
      return sText != null &&
             sSearch != null &&
             (sText.length () - nFromIndex) >= sSearch.length () ? sText.indexOf (sSearch, nFromIndex) : STRING_NOT_FOUND;
    }
docs: Get the first index of sSearch within sText starting at index nFromIndex.
  
  @param sText
  The text to search in. May be <code>null</code>.
  @param nFromIndex
  The index to start searching in the source string
  @param sSearch
  The text to search for. May be <code>null</code>.
  @return The first index of sSearch within sText or {@value #STRING_NOT_FOUND}
  if sSearch was not found or if any parameter was <code>null</code>.
  @see String#indexOf(String,int)