Example usage for java.util.stream Collectors groupingBy

Introduction

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

Prototype

public static <T, K, A, D> Collector<T, ?, Map<K, D>> groupingBy(Function<? super T, ? extends K> classifier,
        Collector<? super T, A, D> downstream)

Source Link

Document

Returns a Collector implementing a cascaded "group by" operation on input elements of type T , grouping elements according to a classification function, and then performing a reduction operation on the values associated with a given key using the specified downstream Collector .

Usage

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

@Benchmark
public Map<Account, DoubleSummaryStatistics> aggregateByAccount_serial_lazy_streams_ec() {
    Map<Account, DoubleSummaryStatistics> accountDoubleMap = this.ecPositions.stream().collect(Collectors
            .groupingBy(Position::getAccount, Collectors.summarizingDouble(Position::getMarketValue)));
    Assert.assertNotNull(accountDoubleMap);
    return accountDoubleMap;
}

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

@Benchmark
public Map<String, DoubleSummaryStatistics> aggregateByCategory_serial_lazy_jdk() {
    Map<String, DoubleSummaryStatistics> categoryDoubleMap = this.jdkPositions.stream().collect(Collectors
            .groupingBy(Position::getCategory, Collectors.summarizingDouble(Position::getMarketValue)));
    Assert.assertNotNull(categoryDoubleMap);
    return categoryDoubleMap;
}

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

@Benchmark
public Map<String, DoubleSummaryStatistics> aggregateByCategory_serial_lazy_streams_ec() {
    Map<String, DoubleSummaryStatistics> categoryDoubleMap = this.ecPositions.stream().collect(Collectors
            .groupingBy(Position::getCategory, Collectors.summarizingDouble(Position::getMarketValue)));
    Assert.assertNotNull(categoryDoubleMap);
    return categoryDoubleMap;
}

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

@Benchmark
public Map<Product, DoubleSummaryStatistics> aggregateByProduct_parallel_lazy_jdk() {
    Map<Product, DoubleSummaryStatistics> result = this.jdkPositions.parallelStream().collect(Collectors
            .groupingBy(Position::getProduct, Collectors.summarizingDouble(Position::getMarketValue)));
    Assert.assertNotNull(result);//www.  ja  va  2 s  .  c o  m
    return result;
}

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

@Benchmark
public Map<Product, DoubleSummaryStatistics> aggregateByProduct_parallel_lazy_streams_ec() {
    Map<Product, DoubleSummaryStatistics> result = this.ecPositions.parallelStream().collect(Collectors
            .groupingBy(Position::getProduct, Collectors.summarizingDouble(Position::getMarketValue)));
    Assert.assertNotNull(result);/*from   www.  j  a  v a  2s.com*/
    return result;
}

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

@Benchmark
public Map<Account, DoubleSummaryStatistics> aggregateByAccount_parallel_lazy_jdk() {
    Map<Account, DoubleSummaryStatistics> result = this.jdkPositions.parallelStream().collect(Collectors
            .groupingBy(Position::getAccount, Collectors.summarizingDouble(Position::getMarketValue)));
    Assert.assertNotNull(result);/*from w  w w . ja  v a 2s.  c  om*/
    return result;
}

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

@Benchmark
public Map<Account, DoubleSummaryStatistics> aggregateByAccount_parallel_lazy_streams_ec() {
    Map<Account, DoubleSummaryStatistics> result = this.ecPositions.parallelStream().collect(Collectors
            .groupingBy(Position::getAccount, Collectors.summarizingDouble(Position::getMarketValue)));
    Assert.assertNotNull(result);//from  ww w  .jav  a 2s .  c  o  m
    return result;
}

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

@Benchmark
public Map<String, DoubleSummaryStatistics> aggregateByCategory_parallel_lazy_jdk() {
    Map<String, DoubleSummaryStatistics> result = this.jdkPositions.parallelStream().collect(Collectors
            .groupingBy(Position::getCategory, Collectors.summarizingDouble(Position::getMarketValue)));
    Assert.assertNotNull(result);/*from   w  w w. j a va2 s. com*/
    return result;
}

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);/*from w ww  . j  a v a2s .co m*/
    return result;
}

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

@Benchmark
public void serial_lazy_jdk() {
    Map<Alphagram, Set<String>> groupBy = this.jdkWords.stream()
            .collect(Collectors.groupingBy(Alphagram::new, Collectors.toSet()));
    groupBy.entrySet().stream().map(Map.Entry::getValue).filter(list -> list.size() >= SIZE_THRESHOLD)
            .sorted(Comparator.<Set<String>>comparingInt(Set::size).reversed())
            .map(list -> list.size() + ": " + list).forEach(e -> Assert.assertFalse(e.isEmpty()));
}