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Copy pathPartitioning.java
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42 lines (34 loc) · 1.54 KB
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package com.brianway.learning.java8.streamapi.collect;
import com.brianway.learning.java8.streamapi.Dish;
import static com.brianway.learning.java8.streamapi.Dish.menu;
import static java.util.Comparator.comparingInt;
import static java.util.stream.Collectors.collectingAndThen;
import static java.util.stream.Collectors.groupingBy;
import static java.util.stream.Collectors.maxBy;
import static java.util.stream.Collectors.partitioningBy;
import java.util.List;
import java.util.Map;
import java.util.Optional;
/**
* 分区
*/
public class Partitioning {
public static void main(String... args) {
System.out.println("Dishes partitioned by vegetarian: " + partitionByVegeterian());
System.out.println("Vegetarian Dishes by type: " + vegetarianDishesByType());
System.out.println("Most caloric dishes by vegetarian: " + mostCaloricPartitionedByVegetarian());
}
private static Map<Boolean, List<Dish>> partitionByVegeterian() {
return menu.stream().collect(partitioningBy(Dish::isVegetarian));
}
private static Map<Boolean, Map<Dish.Type, List<Dish>>> vegetarianDishesByType() {
return menu.stream().collect(partitioningBy(Dish::isVegetarian, groupingBy(Dish::getType)));
}
private static Object mostCaloricPartitionedByVegetarian() {
return menu.stream().collect(
partitioningBy(Dish::isVegetarian,
collectingAndThen(
maxBy(comparingInt(Dish::getCalories)),
Optional::get)));
}
}