public static final boolean isNumeric(String str) {
		int length;
		if (str == null || (length = str.length()) == 0) {
			return false;
		}
		char[] chars = str.toCharArray();
		do {
			// 48-57
			if (chars[--length] < '0' || chars[length] > '9') {
				return false;
			}
		} while (length > 0);
		return true;
	}