How to create a new List from merging 3 ArrayLists in round robin style?

Question

I have 3 arrays. I want to merge the 3 arrays and create a new array that shows all the merged integers. I would like this new array to be in round robin style.

Example input:

array = {arr1 = 1, 2, 3, arr2 = 4, 5, 6, arr3 = 7, 8, 9}

Example output:

arr4 = 1, 4, 7, 2, 5, 8, 3, 6, 9

I'm supposed to use this function but I don't understand how can I use a listOfLists:

String roundRobin(List<List<Integer>>listOfLists) {

Answer 1

I think just loop input and get element and add element to a list of array is easy to understand.

public static List<Integer> roundRobin(List<List<Integer>> listOfLists) {
    if (listOfLists == null || listOfLists.isEmpty()) {
        return new ArrayList<>();
    }

    int maxLength = -1;
    for (List<Integer> list : listOfLists) {
        if (list.size() > maxLength) {
            maxLength = list.size();
        }
    }

    List<Integer> result = new ArrayList<>(maxLength * listOfLists.size());
    for (int i = 0; i < maxLength; i++) {
        for (List<Integer> list : listOfLists) {
            if (i < list.size()) {
                result.add(list.get(i));
            }
        }
    }

    return result;

}