flatmap
What is the use case for flatMap vs map in kotlin
Consider the following example: You have a simple data structure Data with a single property of type List. class Data(val items : List<String>) val dataObjects = listOf( Data(listOf(“a”, “b”, “c”)), Data(listOf(“1”, “2”, “3”)) ) flatMap vs. map With flatMap, you can “flatten” multiple Data::items into one collection as shown with the items variable. val items: … Read more
What is the difference between concatMap and flatMap in RxJava
As you wrote, the two functions are very similar and the subtle difference is how the output is created ( after the mapping function is applied). Flat map uses merge operator while concatMap uses concat operator. As you see the concatMap output sequence is ordered – all of the items emitted by the first Observable … Read more
Return multiple values from ES6 map() function
With using only one reduce() you can do this. you don’t need map(). better approach is this: const values = [1,2,3,4]; const newValues= values.reduce((acc, cur) => { return acc.concat([cur*cur , cur*cur*cur, cur+1]); // or acc.push([cur*cur , cur*cur*cur, cur+1]); return acc; }, []); console.log(‘newValues=”, newValues) EDIT: The better approach is just using a flatMap (as @ori-drori … Read more
Java 8 Streams FlatMap method example
It doesn’t make sense to flatMap a Stream that’s already flat, like the Stream<Integer> you’ve shown in your question. However, if you had a Stream<List<Integer>> then it would make sense and you could do this: Stream<List<Integer>> integerListStream = Stream.of( Arrays.asList(1, 2), Arrays.asList(3, 4), Arrays.asList(5) ); Stream<Integer> integerStream = integerListStream .flatMap(Collection::stream); integerStream.forEach(System.out::println); Which would print: 1 … Read more
In RxJava, how to pass a variable along when chaining observables?
The advice I got from the Couchbase forum is to use nested observables: Observable .from(modifications) .flatmap( (data1) -> { return op1(data1) … .flatmap( (data2) -> { // I can access data1 here return op2(data2); }) }); EDIT: I’ll mark this as the accepted answer as it seems to be the most recommended. If your processing … Read more
When do you use map vs flatMap in RxJava?
map transform one event to another. flatMap transform one event to zero or more event. (this is taken from IntroToRx) As you want to transform your json to an object, using map should be enough. Dealing with the FileNotFoundException is another problem (using map or flatmap wouldn’t solve this issue). To solve your Exception problem, … Read more