2. 코드

public class HarshadNumber {
        public boolean isHarshad(int num) {
                String numStr = num + "";
                int sum = 0;
                for (int inx = 0; inx < numStr.length(); inx++) {
                        sum += Integer.parseInt(numStr.charAt(inx) + "");
                }
                if (num % sum == 0)
                        return true;
                else
                        return false;
        }
 
        public static void main(String[] args) {
                HarshadNumber sn = new HarshadNumber();
                System.out.println("10="+sn.isHarshad(10));
                System.out.println("11="+sn.isHarshad(11));
                System.out.println("12="+sn.isHarshad(12));
                System.out.println("13="+sn.isHarshad(13));
                System.out.println("18="+sn.isHarshad(18));
        }
}