Hi I just wanted to know what is wrong with my code and how can I improve it as it throws an error “stream has already been operated upon or closed” thank you here is my code: I wanted to loop inside the file and check per line if the characters there exceeded 12 characters or not Answer You cannot
Tag: java-stream
Java filtering the object list to string array with stream
I have a class like this and static function like this The problem is inside of filterLength function I can’t return stream as a String array(I want to return content in the Host class) because List holds Host object how can I return as a string in 1 line code? Answer Transform each object in stream You are successfully streaming,
How to get object field for max value in another field in grouped by one more field?
I have list of entities that looks like this: For each code with max version I wanna to get creationDate. I did it like this, but I think that it can be done somehow easier… Answer You can do like this: After grouping by each code then use collectingAndThen collectors and find max item based on version amount and at
Stream / Reduce a series of functions applied to an input value with bound variables in Java
How does one go about rewriting this loop using a stream. It should be possible to rewrite this loop using validators.stream().reduce(…) I have tried using the guidance here, but I cannot figure out what BiFunction interface needs to be implemented and how. The interface as it currently stands looks like this: I have looked at this guidance: Reducing a list
Stream API – how to return map of unique task name – average result?
I have a CourseResult class Here is my method signature I need to return an average result of every task. Answer I’d flatMap that stream to a stream of the taskResults’ entries, and then use Collectors.averagingDouble to get the average per task:
How to Sort List based on Inner Object’s property in java 8
I have classes structure similar to: I have two different tables Source and Target, and after joining them I am getting four columns in the query output. I am constructing Response object using values of these four columns. I have data in Response object with these 4 properties sourceId, sourceName, targetId, targetName. I can have sourceId, sourceName same on the
Reducing ArrayList using MyClass attributes
I have a class, MyClass, like this: If I want to get the sum of amount in an ArrayList of MyClass items, usually I would do this: But now to improve performance, I am trying to use Stream.reduce(). My approach: Is there a better way to do so? And how would the reduction be affected if currAmount or nextAmount is
Convert GraphTraversal<Vertex, Map> into Java8 stream
I have a result of a query to graphDB which returns GraphTraversal<Vertex, Map<Object, List>> values. By using the default methods values.iterate().toStream() it should return a Stream of Stream<Map<Object, List>> which I can handle as a Java8 stream, but for some reason, it does not work, repeat, by using the default methods from gemlin API to get the stream. Note: By
get a list of unique date from the stream grouping
I have data: Want to get a list of dates: [“12-12-2021”, “13-12-2021”] Using stream, I can get a map: I would like to convert to list in from the stream above. Answer groupingBy is not the best choice in your case. Use distinct instead. It will automatically filter out all duplicates.
Map a List to DTO inside map – java
I have such collection: Map<Integer, List<MyObject>> collection I would like to map the whole list of MyObject to MyObjectDTO and return the whole map with the mapped list. So return will be: Map<Integer, List<MyObjectDto>> collectionWithDtos What is the easiest and quickest way? I’ve checked a couple of ways with streams but none of that produced results as I expected. Thanks