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Tag: stream

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)[] 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 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