public static String extractDigits(String s) {
		if (s == null) {
			return StringPool.BLANK;
		}

		StringBuilder sb = new StringBuilder();

		char[] c = s.toCharArray();

		for (int i = 0; i < c.length; i++) {
			if (Validator.isDigit(c[i])) {
				sb.append(c[i]);
			}
		}

		return sb.toString();
	}