private void validate()

in src/main/java/org/apache/commons/csv/CSVFormat.java [2276:2321]
37 lines of code
21 McCabe index (conditional complexity)

    private void validate() throws IllegalArgumentException {
        if (containsLineBreak(delimiter)) {
            throw new IllegalArgumentException("The delimiter cannot be a line break");
        }

        if (quoteCharacter != null && contains(delimiter, quoteCharacter.charValue())) {
            throw new IllegalArgumentException("The quoteChar character and the delimiter cannot be the same ('" + quoteCharacter + "')");
        }

        if (escapeCharacter != null && contains(delimiter, escapeCharacter.charValue())) {
            throw new IllegalArgumentException("The escape character and the delimiter cannot be the same ('" + escapeCharacter + "')");
        }

        if (commentMarker != null && contains(delimiter, commentMarker.charValue())) {
            throw new IllegalArgumentException("The comment start character and the delimiter cannot be the same ('" + commentMarker + "')");
        }

        if (quoteCharacter != null && quoteCharacter.equals(commentMarker)) {
            throw new IllegalArgumentException("The comment start character and the quoteChar cannot be the same ('" + commentMarker + "')");
        }

        if (escapeCharacter != null && escapeCharacter.equals(commentMarker)) {
            throw new IllegalArgumentException("The comment start and the escape character cannot be the same ('" + commentMarker + "')");
        }

        if (escapeCharacter == null && quoteMode == QuoteMode.NONE) {
            throw new IllegalArgumentException("No quotes mode set but no escape character is set");
        }

        // Validate headers
        if (headers != null && duplicateHeaderMode != DuplicateHeaderMode.ALLOW_ALL) {
            final Set<String> dupCheckSet = new HashSet<>(headers.length);
            final boolean emptyDuplicatesAllowed = duplicateHeaderMode == DuplicateHeaderMode.ALLOW_EMPTY;
            for (final String header : headers) {
                final boolean blank = isBlank(header);
                // Sanitise all empty headers to the empty string "" when checking duplicates
                final boolean containsHeader = !dupCheckSet.add(blank ? "" : header);
                if (containsHeader && !(blank && emptyDuplicatesAllowed)) {
                    throw new IllegalArgumentException(
                        String.format(
                            "The header contains a duplicate name: \"%s\" in %s. If this is valid then use CSVFormat.Builder.setDuplicateHeaderMode().",
                            header, Arrays.toString(headers)));
                }
            }
        }
    }