public String toUnicode(String displayText) {
        // Check string for displayable Glyphs,  try and substitute any failed ones
        StringBuilder sb = new StringBuilder(displayText.length());
        for (int i = 0; i < displayText.length(); i++) {
            // Updated with displayable glyph when possible
            sb.append(toUnicode(displayText.charAt(i)));
        }
        return sb.toString();
    }