2553. Separate the Digits in an Array

class Solution {
    public int[] separateDigits(int[] nums) {
        List<Integer> tempList = new ArrayList<>();
        
        for (int num : nums) {
            String numString = String.valueOf(num);
            
            for (char digit : numString.toCharArray()) {
                tempList.add(Character.getNumericValue(digit));
            }
        }
        
        int[] answer = new int[tempList.size()];
        for (int i = 0; i < tempList.size(); i++) {
            answer[i] = tempList.get(i);
        }
        
        return answer;
    }
}