Review

On line 187 EXTENDED.charAt() is invoked without ensuring that the
respective string actually has sufficiently many characters.

• missing/condition/value_or_state

com/itextpdf/text/pdf/Barcode39.java

getCode39Ex(String)

class Barcode39 {
    /** Converts the extended text into a normal, escaped text,
     * ready to generate bars.
     * @param text the extended text
     * @return the escaped text
     */    
    public static String getCode39Ex(String text) {
        StringBuilder out = new StringBuilder("");
        for (int k = 0; k < text.length(); ++k) {
            char c = text.charAt(k);
            if (c > 127)
                throw new IllegalArgumentException(MessageLocalization.getComposedMessage("the.character.1.is.illegal.in.code.39.extended", c));
            char c1 = EXTENDED.charAt(c * 2);
            char c2 = EXTENDED.charAt(c * 2 + 1);
            if (c1 != ' ')
                out.append(c1);
            out.append(c2);
        }
        return out.toString();
    }

}