java - java中如何计算一个数字的数字之和？

Question

我有一个小函数，要求用户输入一个正数，然后给他倒数并计算其数字之和。

代码的第一部分工作正常，但数字之和返回零如何解决这个问题？

我知道必须要求用户输入一次而不是两次，所以如何修复此功能，因为它不接受用户输入。

代码:

package exam3Programing1_20_12_2010;

import java.util.Arrays;
import java.util.Scanner;

public class Question3 {

    private int num;
    private int sum;
    private int reverse;


    public int fill() {

        System.out.println("enter the number");
        Scanner in = new Scanner(System.in);
        num = in.nextInt();

        if (num < 0) {
            System.out.println("enter a positive number");
        }
        while (num != 0) {
            reverse = reverse * 10;
            reverse = reverse + num % 10;
            num = num / 10;
        }
        System.out.println("your reverse number is : " + reverse);
        return num;
    }

    public void sumDigits() {

        while (num != 0) {
            sum = sum + num % 10;
            num = num / 10;
        }

        System.out.println("sum of digits: " + sum);
    }

    public static void main(String[] args) {

        Question3 q3 = new Question3();
        q3.fill();
        q3.sumDigits();
    }
}

输出

enter the number
1234
your reverse number is : 4321
sum of digits: 0

更新后的代码

package exam3Programing1_20_12_2010;

import java.util.Arrays;
import java.util.Scanner;

public class Question3 {

    private int num;
    private int sum;
    private int reverse;


    public int fill() {

        int myNumber = num;
        System.out.println("enter the number");
        Scanner in = new Scanner(System.in);
        myNumber = in.nextInt();

        if (myNumber < 0) {
            System.out.println("enter a positive number");
        }
        while (myNumber != 0) {
            reverse = reverse * 10;
            reverse = reverse + myNumber % 10;
            myNumber = myNumber / 10;
        }
        System.out.println("your reverse number is : " + reverse);
        return num;
    }

    public void sumDigits() {

        while (num != 0) {
            sum = sum + num % 10;
            num = num / 10;
        }

        System.out.println("sum of digits: " + sum);
    }

    public static void main(String[] args) {

        Question3 q3 = new Question3();
        q3.fill();
        q3.sumDigits();
    }
}

更新输出

enter the number
1234
your reverse number is : 4321
sum of digits: 0

Answer 1

这是因为您在反向方法和求和方法中共享相同的数字，并且当您第一次调用反向方法时，您会继续将数字除以0，因此当您使用求和方法时，您的数字是1，因此总和是0。

为了纠正这个问题，我建议您定义名为 mynumber 的局部变量，如下所示:

public int fill() {

    System.out.println("enter the number");
    Scanner in = new Scanner(System.in);
    num = in.nextInt();

    if (num < 0) {
        System.out.println("enter a positive number");
    }
    int myNumber = num;  
    while (myNumber != 0) {
        reverse = reverse * 10;
        reverse = reverse + myNumber % 10;
        myNumber = myNumber / 10;
    }
    System.out.println("your reverse number is : " + reverse);
    return num;
}

OUTPUT:
enter the number
1234
your reverse number is : 4321
sum of digits: 10