public static BigInteger createBigInteger()

in src/main/java/org/apache/commons/lang3/math/NumberUtils.java [185:215]

• 30 lines of code
• 11 McCabe index (conditional complexity)

    public static BigInteger createBigInteger(final String str) {
        if (str == null) {
            return null;
        }
        if (str.isEmpty()) {
            throw new NumberFormatException("An empty string is not a valid number");
        }
        int pos = 0; // offset within string
        int radix = 10;
        boolean negate = false; // need to negate later?
        final char char0 = str.charAt(0);
        if (char0 == '-') {
            negate = true;
            pos = 1;
        } else if (char0 == '+') {
            pos = 1;
        }
        if (str.startsWith("0x", pos) || str.startsWith("0X", pos)) { // hex
            radix = 16;
            pos += 2;
        } else if (str.startsWith("#", pos)) { // alternative hex (allowed by Long/Integer)
            radix = 16;
            pos++;
        } else if (str.startsWith("0", pos) && str.length() > pos + 1) { // octal; so long as there are additional digits
            radix = 8;
            pos++;
        } // default is to treat as decimal

        final BigInteger value = new BigInteger(str.substring(pos), radix);
        return negate ? value.negate() : value;
    }