Java - How to store an integer objects value into an integer array?

Question

I have an integer, lottoNum generated from the java utility Random. I need to store the integer value of int lottoNum in an integer array called sumArray, so I can iterate through the array to add the value of each number. If lottoNum = 123456, the integer array should be sumArray[] = {1, 2, 3, 4, 5, 6}; I'm not sure how to do this and hope I can get some help.

This is my code for the int lottoNum

// generate sets of random numbers between 1-9
randNum = genNumbers.nextInt(10);
// store the numbers into lottoNum
lottoNum = (lottoNum * 10) + randNum;

lottoNum gets passed into another class where the math is supposed to be performed, then returned as sum.

This is my code to iterate through the array to add the numbers up

public int doMath(lottoNum) {
 int sumArray[] = {};
 int sum = 0;
 for (int i : sumArray)
 sum += i;
 return sum; 
}

How (or can I) place the value of lottoNum into the {} of the array? I was reading something about splitting the numbers in lottoNum, but I'm completely lost on this.

I also found this code to get separate digits of an integer, but an not sure how to put the output into the array.

int number; // = some int
while (number > 0) {
 print( number % 10);
 number = number / 10;
}

Help is greatly appreciated.

• Thomas Böhm: It would be a good idea to learn Java by reading a book or do an online-tutorial. This question is part of the Basics you can learn by reading the first chapters of one of the Java-books available!
• Cannoli: Thank you, I'm in week two of a Java class, so I'm doing just as you suggested. Is this site only for experienced programmers to ask questions?
• Matthew Wright: Why not store the values in an array from the start? Since you seem to be just wanting the sum, try using lottoNum % 10 in a loop to get the values in the ones position.
• EcstaticSnow: @Cannoli This site is for any programmer(complete beginner - Expert Level). All you have to do is show that you tried something, you've tried looking it up before asking the question, you add what you have tried to your question, and the question is on topic according to the site.

Answer 1

The result will be in arr, and will be in the reversed order of the digits in the original number. Say number is 123, and the result array will be {3, 2, 1}.

int number; // = some int
List<Integer> arrList = new ArrayList<>();
while (number > 0) {
 // To keep the same order, use arrList.add(0, number % 10);
 arrList.add(number % 10);
 number = number / 10;
}
Integer[] arr = new Integer[arrList.size()];
arrList.toArray(arr);

or you can convert the number to string and then convert each character to a digit;

int number; // some number
char[] numChars = Integer.toString(number).toCharArray();
int arr[] = new int[numChars.length];
for (int i = 0; i < numChars.length; ++i) {
 arr[i] = numChars[i] - '0';
}

• Cannoli: Thank you so much for your help! I'm incorporating this in the code now and will report back. I greatly appreciate you taking your time to help me with, what appears to be, such a basic question.