Example usage for java.util.stream Collectors summarizingDouble

Introduction

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

Prototype

public static <T> Collector<T, ?, DoubleSummaryStatistics> summarizingDouble(
        ToDoubleFunction<? super T> mapper)

Source Link

Document

Returns a Collector which applies an double -producing mapping function to each input element, and returns summary statistics for the resulting values.

Usage

From source file:org.eclipse.collections.impl.jmh.AggregateByTest.java

@Benchmark
public Map<String, DoubleSummaryStatistics> aggregateByCategory_parallel_lazy_streams_ec() {
    Map<String, DoubleSummaryStatistics> result = this.ecPositions.parallelStream().collect(Collectors
            .groupingBy(Position::getCategory, Collectors.summarizingDouble(Position::getMarketValue)));
    Assert.assertNotNull(result);/*w  w  w  . ja va2  s .  co m*/
    return result;
}

From source file:pl.prutkowski.java.playground.java8.TestCollectors.java

/**
 * @param args the command line arguments
 *///from w  w w  .j av a 2  s. co m
public static void main(String[] args) {
    Map<String, Integer> monthByLen = months.stream()
            .collect(Collectors.toMap(String::toUpperCase, m -> StringUtils.countMatches(m, "e")));

    monthByLen.forEach((month, eCount) -> System.out.println(month + " -> " + eCount));

    System.out.println("---------------------------------");

    Map<Object, List<String>> monthByLen2 = months.stream()
            .collect(Collectors.groupingBy(m -> StringUtils.countMatches(m, "e")));

    monthByLen2.forEach((count, groupedMonths) -> System.out.println(count + " -> " + groupedMonths));

    System.out.println("---------------------------------");

    Double averageLength = months.stream().collect(Collectors.averagingDouble(String::length));
    System.out.println("Average length: " + averageLength);
    System.out.println("---------------------------------");

    Double max = months.stream().collect(Collectors.summarizingDouble(String::length)).getMax();
    System.out.println("Max length: " + max);
    System.out.println("---------------------------------");

    String reduced = months.stream().collect(Collectors.reducing((m1, m2) -> (m1 + ", " + m2))).get();
    System.out.println("Reduced: " + reduced);
    System.out.println("---------------------------------");
    System.out.println(String.join(", ", months));
    System.out.println("---------------------------------");

    List<String> monthsWithZ = months.stream().filter(m -> m.contains("z")).collect(new ListCollector<>());
    System.out.println(monthsWithZ);

}