I know how to create a Map<T, List<U>> , using Collectors.groupingBy:Map<Key, List<Item>> listMap = items.stream().collect(Collectors.groupingBy(s->s.key));
There are easy solutions for concatenating two String or Integer in java by Streams. Since int is frequently used. Is there any straightforward way for concatenating two int?
I have a TreeSet of Strings (hardcoded). Want to check that a given parameter String eg. "Person" if present in the TreeSet then return true otherwise return false.
Lets say I have two classes and two methods:Why does getItems2 compile while getItems gives compiler error
I have a List<String> in java and it contains some Strings.I also have a hashmap with String values and I would like to check if there's any element in my List that is not in the Hashmap. This is the code I wrote:
Let's say I've got a list of Strings and I want to filter them by the list of filtering Strings. For the list which consists of: "abcd", "xcfg", "dfbf"
OUTPUTI am trying to find a clever ways to grep all keys where its values are greater than X for example, if X == 3, it should return oranges, and watermelons and kiwis
Is there an elegant way to convert a Map<P, Optional<Q>> to a sparse Map<P, Q> ?This should work, but it's a bit meh:
I have a nested list of Long. for example:Is there a way using streams to create a new list of items that are present in all the lists:
Let's say my original Map contains the following:And I want to create a reversed Map containing the following: