Java 8 Grouping elements in groups of X

Question

My question is very straightforward... I have a list of elements and I want to make subgroups of certain amount... Could that be done in Java with an API ?... Or I should start playing with counters etc...

Does this answer your question? [Java: how can I split an ArrayList in multiple small ArrayLists?](https://stackoverflow.com/questions/2895342/java-how-can-i-split-an-arraylist-in-multiple-small-arraylists) — Tobias, Feb 09 '21 at 18:51
You say your question is straightforward but I disagree. It is vague and not precise. It is lacking details and is generally unclear. Downvoted and voting to close because of that. Please see [ask]. — Zabuzard, Feb 09 '21 at 18:52

score 2 · Accepted Answer · answered Feb 09 '21 at 18:48

Not really necessary to find an API just for this.

Here's a simple method to do what you want:

public static <T> List<List<T>> splitList(int groupSize, List<T> list) {
    List<List<T>> subLists = new ArrayList<>();
    for (int i = 0; i < list.size();) {
        subLists.add(list.subList(i, i = Math.min(i + groupSize, list.size())));
    }
    return subLists;
}

public static void main(String[] args) throws Exception {
    List<Integer> list = List.of(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13);
    List<List<Integer>> subLists = splitList(3, list);
    System.out.println(subLists);
    // prints [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11, 12], [13]]
}

Java 8 Grouping elements in groups of X

1 Answers1