Skip to content

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

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