Method indexOf

src/main/java/org/apache/commons/lang3/Strings.java:831–833

Finds the first index within a CharSequence, handling null. This method uses String#indexOf(String, int) if possible. A null CharSequence will return -1. Case-sensitive examples Strings.CS.indexOf(null, ) = -1 Strings.CS.indexOf( ,

(final CharSequence seq, final CharSequence searchSeq)

     * @return the first index of the search CharSequence, -1 if no match or {@code null} string input
     */
    public int indexOf(final CharSequence seq, final CharSequence searchSeq) {
        return indexOf(seq, searchSeq, 0);
    }

    /**
     * Finds the first index within a CharSequence, handling {@code null}. This method uses {@link String#indexOf(String, int)} if possible.