From this guide, computeIfAbsent is used to create and update the value list, but how is it achieved? Here for map.computeIfAbsent("key1", k -> new ArrayList<>()).add("value2"); I was expecting no updates since key1 exist, however it ends up adding "value2" to the value list Map<String, List<String>> map = new HashMap<>(); map.computeIfAbsent("key1", k -> new ArrayList<>()).add("value1"); map.computeIfAbsent("key1",… Read More Puzzling about how computeIfAbsent works to update duplicate key->list value pair

How to remove element from an Integer type Vector in JAVA by using remove(Object o)? This is a short snippet of what I did. I’m new to Java. Vector<Integer> v = new Vector<>(); v.add(1); v.add(2); v.add(3); Object remInd = v.remove(0); // Index based, THIS WORKS!!! boolean remElem = v.remove("3"); // HOW TO MAKE THIS WORK?… Read More Remove element from Vector(any collection) in JAVA

my nested collections looks like this: User–> drugs–> drugsTime I want to update data in document in the subsub-collection (drugsTime) however I dont know the drug document id and the drugtime document id so I did the following : ConfirmDrugTaken(DateTime d) async { final User? user = FirebaseAuth.instance.currentUser; final _uid = user?.uid; var drugID=""; //… Read More Flutter entering to sub-sub collection in firebase

I cant solve this task. There are N cyclopes and an array of N elements. Every element is eyesight value of single cyclop. Every cyclop needs a lens with a value K but he will be okay with lens of value K+1 or K-1. Cyclopes always buy lenses in pairs. For example 5 cyclopes with… Read More How to remove two elements of collection at the same time? Task about cyclopes lenses

I have a collection that contain two arrays : array:2 [ 0 => array:3 [ "Code" => "AKAR02" "startDate" => "2022-10-27" "endDate" => null ] 1 => array:3 [ "Code" => "AKAR02" "startDate" => "2022-10-27" "endDate" => null ] ] take the first element if they have the same code & the same start date… Read More Take the first element if exist

I was surprised to find that using Java 17 here, converting from a List to a Set returned sorted results. Why is that? I thought the Set interface and its default implementation, HashSet, did no sorting. I confirmed these results in at last one more online environment. What am I missing? import java.util.*; public class… Read More Convert List to Set returns sorted results?

I know that there are different ways to solve this task, but I need a particular way using replaceAll() method. I just stuck with right condition in the expression. So I have a method like this: public static void handleComments(List<Comment> comments, int maxTextLength) { comments.replaceAll(comment -> comment.getText().length() > maxTextLength ? *what should be here?* :… Read More Remove a part of string based on its given length with replaceAll in Java

I have the following Python list with a predefined N: l = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] N = 3 I would like to have a collection of N elements (a list of lists, for example) from the list (if len(l) % !=0 then the last collection could be shorter… Read More How to fetch (pop) N elements from a Python list iteratively while list exhausts?

I want to find a person from a list, or throw a PersonNotFoundException otherwise. The first() function from kotlin.collections throws NoSuchElementException in this scenario, but I want to throw my custom exception i.e. PersonNotFoundException. Currently I’m using the following logic: val persons: List<Person> = listOf(…) val name: String = "Bob" persons.firstOrNull { it.name == name… Read More Throw custom exception when item not found in a Kotlin collection