I have a stream from elements of a class x. One of the arributes (t) of the class x is from type LocalDateTime and I need to group the elements by hours. I tried something like this: But this syntax doesn´t work, any other idea of what i might be able to do? Answer The attempt is actually pretty close.
Tag: collectors
Java Stream – Collecting Parent-objects into a Set after applying flatMap()
Is it possible to go back to the parent-object after applying flatmap() operation, and accumulate parent-objects into a set? I have an UnifiedOfferEntity with set of other entity objects as a field: I would like to filter through fields of the parent-object (UnifiedOfferEntity) like this: And then I would like to examine the nested collection, filter through child-objects (ContractDetailsEntity): And
Convert a List of JSON-objects input into a nested Map
I have a String input in the following format: Input String: [{ “id”:”1″, “name”:”A”, “address”:”St 1″},{ “id”:”2″, “name”:”B”, “address”:”St 2″}, …] And I want to be able to convert this to a Map<String, Map<String, String>> format. So, something like: Required Output Format: {1: {id:1, name:”A”, address: “St 1″} 2: {id:2, name:”B”, address: “St 2”}} I created a class to help
Java Stream GroupBy and Reduce
I have an Item class which contains a code, quantity and amount fields, and a list of items which may contain many items (with same code). I want to group the items by code and sum up their quantities and amounts. I was able to achieve half of it using stream’s groupingBy and reduce. The grouping by worked, but the
GroupBy and Stream Filter based on max field for particular record on each date java list
I am having a list that looks like below What i would like to achieve is to filter like for example on date 2022-08-27 and also on date 2022-08-26 respectively i only return one record which is having the maximum currentSpeed such that my final list looks like below Below is how my code looks like and the way i
Java – Collectors Group By and Expand Map by number of records
I have the following java list of UserRecords objects that are grouped by user_name. I want to be able to break down this list into small batches of 5 records if a user has more than 5 records. Here’s the result of my user group: Since Jane Doe has more than 5 records, I would like her results to be
Creating a Map from an Array of int – Operator ‘%’ cannot be applied to ‘java.lang.Object’
I have code like this, which is supposed to create a Map from an array of integers. The key represents the number of digits. The problem is in the line with mapping(). I’m getting an error: Does someone know how to solve this? Answer The flavor of collect() that expects a Collector as an argument isn’t available with primitive streams.
Create a SortedMap from a List objects with the Value represented as a list of N lowest object’s attributes mapped to a particular Key
I am working with a CSV file which includes some information about accidents. I’ve created the Accident type: I’ve also created a function that reads all the CSV file, converts all the accidents to a List<Accident> and saves it to this type AccidentArchive: So, we are working with streams which I don’t understand entirely yet, and I’ve been stuck in
How to create a map with an attribute as a key and a maximum value as a value
So, In college we are working with csv files and streams. Right now I am doing some homework but I’ve been stuck in this exercise for some days now. I have a csv file with some data about accidents (like the accident severity, the number of victims and so) and I have a function that reads that data and converts
Java Streams – group-by and return a Nested Map
my data is like this, my goal is put every unitId and value into a map like this, I already figure out two ways to achieve that, here is my code, and, First one more like write the processing manually, second one uses temporary lists which may not be necessary. Is there any direct or simple way to do this,