# Digit sum loops+random positive number generator

I have to prepare program that summing the digits of two given by user numbers and then give back the random number which is

• natural number
• the digit sum of this number is bigger then the digit sum of given by user numbers

It's look like everything is ok but i dont know if it is just luck in random number generator or it's working well. Thank you for review.

import java.util.Random;

import java.util.Scanner;

public class Ex1 {

public static void main(String[] args) {
Random rnd = new Random();
Scanner scn = new Scanner(System.in);
int sum1 = 0;
int sum2 = 0;
int sum3 = 0;
int sum4 = 0;
System.out.println("1TH NUMBER : ");
int a1 = scn.nextInt();
System.out.println("2ND NUMBER : ");
int a2 = scn.nextInt();
System.out.println((0 > a1 || 0 > a2 ? "ERROR-NEGATIVE NUMBER" : "OK"));
while (a1 > 0) {
sum1 += a1 % 10;
a1 /= 10;
}
//System.out.println(sum1);
while (a2 > 0) {
sum2 += a2 % 10;
a2 /= 10;
}
//System.out.println(sum2);
int temp = sum1 + sum2; //temporary-for storage /=
while (temp > 0) {
sum3 += (temp) % 10;
(temp) /= 10;
}
// System.out.println(sum3);
while (true) {
int a3 = rnd.nextInt(Integer.MAX_VALUE);
sum4 += (a3) % 10;
(a3) /= 10;
// System.out.println(sum4);
if (sum4 > sum3) {
System.out.println(a3 + " this is my number");
break;
}
}

}
}

• Could you provide some pairs of examples? (input -> expected output) Feb 22 '20 at 21:21
• Ex1 : Input: a1 = 222 - so digit sum = 6; a2 = 333 - so digit sum = 9; sum of digits from a1 and a2= 15 = 1 + 5 = 6 so i expect the number with higher digit sum like Output 4545 because 4+5+4+5 = 18 Ex2 Input - a1 - 23234 (digit sum= 14) a2 - 454545(digit sum=27), sum of digits a1+a2 = 14+27 = 41 = 4 + 1 = 5 Output: a3=61= 6+1 = 7  (higher digit sum) Feb 22 '20 at 21:42
• @AdamK I suggest that you edit your answer and add the inputs and outputs, that you gave, in a table / formatted. Feb 22 '20 at 21:47

I have some suggestion for you.

### Code duplication

In your code, you have some code duplication that can be extracted in a method. By extracting the code, the code will become shorter, be less error-prone and easier to read.

1. I suggest that you make a method to print a question and read the user input.
public static void main(String[] args) {
//[...]
//[...]
}

System.out.println(s);
return scn.nextInt();
}

1. Since the logic is the same to handle the sum, you can extract both of the while into a method. This extraction will remove lots of code!

public static void main(String[] args) {
//[...]
int sum1 = getSum(a1);
int sum2 = getSum(a2);

int temp = sum1 + sum2; //temporary-for storage /=

int sum3 = getSum(temp);
//[...]
}

private static int getSum(int userInput) {
int currentSum = 0;
while (userInput > 0) {
currentSum += userInput % 10;
userInput /= 10;
}
return currentSum;
}


### Other observations

1. In my opinion, I would extract the last calculation in a method and return the result.
public static void main(String[] args) {
//[...]
int number = findNumber(rnd, sum3);
System.out.println(number + " this is my number");
//[...]
}

private static int findNumber(Random rnd, int sum3) {
int sum4 = 0;
while (true) {
int a3 = rnd.nextInt(Integer.MAX_VALUE);
sum4 += (a3) % 10;
(a3) /= 10;
if (sum4 > sum3) {
return a3;
}
}
}


### Refactored code

public static void main(String[] args) {
Random rnd = new Random();
Scanner scn = new Scanner(System.in);

System.out.println((0 > a1 || 0 > a2 ? "ERROR-NEGATIVE NUMBER" : "OK"));

int sum1 = getSum(a1);
int sum2 = getSum(a2);
int temp = sum1 + sum2; //temporary-for storage /=

int sum3 = getSum(temp);

int number = findNumber(rnd, sum3);
System.out.println(number + " this is my number");
}

private static int findNumber(Random rnd, int sum3) {
int sum4 = 0;
while (true) {
int a3 = rnd.nextInt(Integer.MAX_VALUE);
sum4 += (a3) % 10;
(a3) /= 10;
if (sum4 > sum3) {
return a3;
}
}
}

private static int getSum(int userInput) {
int currentSum = 0;
while (userInput > 0) {
currentSum += userInput % 10;
userInput /= 10;
}
return currentSum;
}

System.out.println(s);
return scn.nextInt();
}


Welcome to Code Review, you are not closing the Scanner resource and this is a resource leak: to avoid this you can use from java 8 the construct try-with-resource like below:

try (Scanner scn = new Scanner(System.in)) {

System.out.println((0 > a1 || 0 > a2 ? "ERROR-NEGATIVE NUMBER" : "OK"));

using Math.min in the following way:
System.out.println(Math.min(a1, a2) < 0 ? "ERROR-NEGATIVE NUMBER" : "OK");