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: stream
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
How to match equals() and hashCode in streams?
I have a stream where I am aggregating some data like this: The problem is that by adding this comparator I am braking the contract between hashCode() and equals() and at the end I have duplicate keys: Has anyone some ideas how can I fix this? Or is there a way to sort the final object ( Map<String, Map<String, Map<EventType,
How to collect a list of doubles from a stream?
say I desire to collect a list of doubles[] from a lambda function, I have created the following example, however it do not compile given the type. What could I do as a workaround? Here is the compilation error: As an attempt I have tried the following However it prompts this compilation error: Moreover I have seen (here)[https://docs.oracle.com/javase/8/docs/api/java/util/stream/package-summary.html] that fiven
Java Filter one stream based on another stream and collect
I have this code working with a for loop and steam, but I was wondering I can improve it using two streams. Here I want to replace the for loop with a stream and would like to get a list of String that the method returns. Answer I was able to find a quick and dirty solution, of course not
How to create a custom Uniform Fan Out Shape in Akka through the Java library
So I am building an Akka custom component to learn the framework. I need to create a UnifromFanOut shape custom component. So I tried to extend the shape but the issue is how do I create the shape with 1 input and 3 outputs. The class requires a seq object which is a part of Scala but I am a
How to filter a hashmap with specific conditions
I have the following initial hashmap: LatS=[59, 48, 59, 12, 48] LatD=[41, 42, 46, 42] EW=[W, W, W, W] NS=[N, N, N, N] LonM=[39, 23, 30, 48] State=[OH, SD, WA, MA] LatM=[5, 52, 35, 16] City=[Youngstown, Yankton, Yakima, Worcester] LonS=[0, 23, 36, 0] LonD=[80, 97, 120, 71] I want to filter the Hashmap using the method query that has the
Create a merged map with list of maps
I’m new to java so seeking help from experts. any help would be much appreciated, and a scope for me to learn new things. I want to create a List of maps(resultList) from a another list of maps(list) where a single map(keys) contains values which are keys to the list of maps(map1, map2, map3 … So on). Like below example
How to map Iterable to its DTO?
I have the following repository: PermissionRepository: In my service, I am trying to map Permission entity to PermissionDTO, but as findAll() method returns Iterable<T> (Iterable<T> findAll();), I cannot convert as shown below as I generally use for List<T>. It throws “Cannot resolve method ‘stream’ in ‘Iterable'” error for the .stream() method. So, how can I map this Permission entity to
Separate List in Java
I need help on separating List. I am really new to this I have a code that results to this [[a, b, c, d, e], f] setOfLetters() is from a query My question is how can I make my result like this? [a, b, c, d, e, f] Is it by using for loop? Or anything you can suggest. Thanks