ccf201512-1数位之和

charAt，与字符'0',做差值。

import java.util.Scanner;

public class Main3 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String num = scanner.nextLine();
        char[] arr = num.toCharArray();
        int sum = 0;
        for(char c : arr){
            int tmp = c - '0';
            sum+=tmp;
        }
        System.out.println(sum);
    }
}

第二种解法

import java.util.Scanner;

public class Main10 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int i = scanner.nextInt();
//        System.out.println(i);
        int sum = 0;//各位数字
        while(i > 0){
            int tmp = i%10;
            i = i /10;
            sum+=tmp;
        }
        System.out.println(sum);
    }
}