Example usage for java.util.stream Collectors groupingByConcurrent

Introduction

In this page you can find the example usage for java.util.stream Collectors groupingByConcurrent.

Prototype

public static <T, K> Collector<T, ?, ConcurrentMap<K, List<T>>> groupingByConcurrent(
        Function<? super T, ? extends K> classifier) 

Source Link

Document

Returns a concurrent Collector implementing a "group by" operation on input elements of type T , grouping elements according to a classification function.

Usage

From source file:Main.java

public static void main(String[] args) {
    List<String> strings = new LinkedList<>();
    strings.add("a");
    strings.add("B");
    strings.add("ab");
    strings.add("abc");
    strings.add("ABC");

    ConcurrentMap<Integer, List<String>> byLength = strings.parallelStream()
            .collect(Collectors.groupingByConcurrent(String::length));

    System.out.println(byLength);
}

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From source file:Main.java

public static void main(String[] args) {
    List<Person> roster = createRoster();
    ConcurrentMap<Person.Sex, List<Person>> byGenderParallel = roster.parallelStream()
            .collect(Collectors.groupingByConcurrent(Person::getGender));

    List<Map.Entry<Person.Sex, List<Person>>> byGenderList = new ArrayList<>(byGenderParallel.entrySet());

    System.out.println("Group members by gender:");
    byGenderList.stream().forEach(e -> {
        System.out.println("Gender: " + e.getKey());
        e.getValue().stream().map(Person::getName).forEach(f -> System.out.println(f));
    });/*from   ww  w  .  j av a2s.c  om*/

}

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