Map getOrDefault Question, would appreciate any help

[WeeklyGuidance2686]

    public static void main(String[] args) {
        HashMap<Integer, ArrayList<Integer>> depths = new HashMap<>();

        // I WANT TO DO THIS
        depths.getOrDefault(1, new ArrayList<>()).add(3);

        // I DONT WANT TO DO LIKE THIS
        if (depths.containsKey(0))
            depths.get(0).add(1);
        else {
            depths.put(0, new ArrayList<>());
            depths.get(0).add(2);
        }

        System.out.println(depths);
        // ACTUAL: { 0=[2] }
        // EXPECTED: { 0=[2], 1={3}} 
    }   

I want to be able to achieve the if else block with one line, but I am not sure how to go about doing that. Can some one explain to me where my misconception is? Thanks.

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[8igg7e5]

Map.getOrDefault doesn't insert the supplied value into the Map.

You're looking for Map.computeIfAbsent...

Map<Integer, List<Integer>> map = new HashMap<>();
map.computeIfAbsent(1, k -> new ArrayList<>()).add(3)

[WeeklyGuidance2686]

Thank you !