CODEWITHSUNDEEP
javajava-8java-stream
Kalle Richter
Kalle Richter

Reputation: 8728

How to get n first values from an Iterator in Java 8?

I have sorted a HashMap using Sort a Map<Key, Value> by values (Java) to that I have a LinkedHashMap, i.e. an Iterable which garantees iteration order.

Now, I'd like to retrieve a java.util.List of the first n entries of the map with a one-liner, if possible with a Java 8 Collection Stream API-technique.

I found how can i get two consecutive values from Iterator which explains that there's a possibility to do that with an array, but that's not elegant, differs from my intention to get a List (although that can be transformed, but it's an unnecessary step) and requires an extra method.

Upvotes: 7

Views: 5789

Answers (2)

user_3380739
user_3380739

Reputation: 1254

Writing more concise code with StreamEx:

List<Map.Entry<Key,Value>> firstN = EntryStream.of(map).limit(n).toList();

Upvotes: 1

Eran
Eran

Reputation: 393851

Stream the entrySet and limit the Stream to the first n elements:

List<Map.Entry<Key,Value>> firstN = 
    map.entrySet().stream().limit(n).collect(Collectors.toList());

Upvotes: 17

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