java code to check if string is alphanumeric

 javaCopypublic class CheckCharAlpha {
    public static void main(String[] args) {

        boolean letterOrDigit = isAlphaNumeric('k');
        System.out.println(letterOrDigit);
    }

    public static boolean isAlphaNumeric(char char1) {
        return (char1 >= 'a' && char1 <= 'z') || (char1 >= 'A' && char1 <= 'Z') || (char1 >= '0' && char1 <= '9');
    }
}