Example usage for java.util.stream Collectors toConcurrentMap

Introduction

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

Prototype

public static <T, K, U> Collector<T, ?, ConcurrentMap<K, U>> toConcurrentMap(
        Function<? super T, ? extends K> keyMapper, Function<? super T, ? extends U> valueMapper,
        BinaryOperator<U> mergeFunction) 

Source Link

Document

Returns a concurrent Collector that accumulates elements into a ConcurrentMap whose keys and values are the result of applying the provided mapping functions to the input elements.

Usage

From source file:Main.java

public static void main(String[] args) {
    Map<Employee.Gender, Long> countByGender = Employee.persons().stream().collect(Collectors
            .toConcurrentMap(Employee::getGender, p -> 1L, (oldCount, newCount) -> newCount + oldCount));

    System.out.println(countByGender);
}

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From source file:Main.java

public static void main(String[] args) {
    List<String> terms = Arrays.asList("this", "is", "is", "a");

    Map<String, Integer> result = terms.parallelStream().flatMap(s -> Arrays.asList(s.split(" ")).stream())
            .collect(Collectors.toConcurrentMap(w -> w.toLowerCase(), w -> 1, Integer::sum));
    System.out.println(result);//from w w  w  .  j  av  a 2 s . c o m
}

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From source file:ru.anr.base.BaseParent.java

/**
 * A short-cut function to simplify the process of building a map from a
 * collection when there can be non-unique keys.
 * /* www  . jav a  2s .  c  o m*/
 * @param collection
 *            An original collection
 * @param keyMapper
 *            A key mapper
 * @param valueMapper
 *            A value mapper
 * @param mergeFunction
 *            A function to merge values conflicting by their key
 * @return A new map
 * 
 * @param <T>
 *            The type of a collection item
 * @param <K>
 *            Type of the map key
 * @param <U>
 *            Type of the map value
 */
public static <T, K, U> Map<K, U> toMap(Collection<T> collection, Function<? super T, ? extends K> keyMapper,
        Function<? super T, ? extends U> valueMapper, BinaryOperator<U> mergeFunction) {

    return collection.stream().collect(Collectors.toConcurrentMap(keyMapper, valueMapper, mergeFunction));
}

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