Example usage for java.util.stream Collectors mapping

Introduction

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

Prototype

public static <T, U, A, R> Collector<T, ?, R> mapping(Function<? super T, ? extends U> mapper,
        Collector<? super U, A, R> downstream) 

Source Link

Document

Adapts a Collector accepting elements of type U to one accepting elements of type T by applying a mapping function to each input element before accumulation.

Usage

From source file:Main.java

public static void main(String... args) {
    Map<Type, Set<CaloricLevel>> o = Food.menu.stream()
            .collect(Collectors.groupingBy(Food::getType, Collectors.mapping(dish -> {
                if (dish.getCalories() <= 400)
                    return CaloricLevel.DIET;
                else if (dish.getCalories() <= 700)
                    return CaloricLevel.NORMAL;
                else
                    return CaloricLevel.FAT;
            }, Collectors.toSet())));

    System.out.println(o);// www.j a va 2s.c  o m

}

---

From source file:Main.java

public static void main(String[] args) {
    Map<Employee.Gender, String> namesByGender = Employee.persons().stream().collect(Collectors
            .groupingBy(Employee::getGender, Collectors.mapping(Employee::getName, Collectors.joining(", "))));
    System.out.println(namesByGender);
}

---

From source file:Main.java

public static void main(String[] args) {
    Map<Boolean, String> partionedByMaleGender = Employee.persons().stream().collect(Collectors
            .partitioningBy(Employee::isMale, Collectors.mapping(Employee::getName, Collectors.joining(", "))));
    System.out.println(partionedByMaleGender);
}

---

From source file:Main.java

public static void main(String[] args) {
    Map<Employee.Gender, List<String>> namesByGender = Employee.persons().stream().collect(Collectors
            .groupingBy(Employee::getGender, Collectors.mapping(Employee::getName, Collectors.toList())));

    System.out.println(namesByGender);
}

---

From source file:Main.java

public static void main(String[] args) {
    Map<Employee.Gender, String> namesByGender = Employee.persons().stream()
            .collect(Collectors.groupingByConcurrent(Employee::getGender,
                    Collectors.mapping(Employee::getName, Collectors.joining(", "))));
    System.out.println(namesByGender);
}

---

From source file:Main.java

public static void main(String[] args) {
    Map personsByGenderAndDobMonth = Employee.persons().stream().collect(
            Collectors.groupingBy(Employee::getGender, Collectors.groupingBy(p -> p.getDob().getMonth(),
                    Collectors.mapping(Employee::getName, Collectors.joining(", ")))));

    System.out.println(personsByGenderAndDobMonth);
}

---

From source file:Main.java

public static void main(String[] args) {
    Map<Gender, Map<Object, String>> personsByGenderAndDobMonth = Employee.persons().stream().collect(
            Collectors.groupingBy(Employee::getGender, Collectors.groupingBy(p -> p.getDob().getMonth(),
                    Collectors.mapping(Employee::getName, Collectors.joining(", ")))));

    System.out.println(personsByGenderAndDobMonth);
}

---

From source file:Main.java

public static void main(String[] args) {
    Map<Month, String> dobCalendar = Employee.persons().stream()
            .collect(Collectors.collectingAndThen(Collectors.groupingBy(p -> p.getDob().getMonth(),
                    Collectors.mapping(Employee::getName, Collectors.joining(" "))), result -> {
                        for (Month m : Month.values()) {
                            result.putIfAbsent(m, "None");
                        }//from   w w  w .jav a 2 s . c  om
                        return Collections.unmodifiableMap(new TreeMap<>(result));
                    }));

    dobCalendar.entrySet().forEach(System.out::println);
}

---

From source file:Main.java

public static void main(String[] args) {
    List<Person> roster = createRoster();

    System.out.println("Names by gender:");
    Map<Person.Sex, List<String>> namesByGender = roster.stream().collect(
            Collectors.groupingBy(Person::getGender, Collectors.mapping(Person::getName, Collectors.toList())));

    List<Map.Entry<Person.Sex, List<String>>> namesByGenderList = new ArrayList<>(namesByGender.entrySet());

    namesByGenderList.stream().forEach(e -> {
        System.out.println("Gender: " + e.getKey());
        e.getValue().stream().forEach(f -> System.out.println(f));
    });//w  ww  . ja v  a  2  s . c o  m

}

---

From source file:Main.java

public static <T, K, V> HashMap<K, HashSet<V>> group(Collection<T> entities, Function<T, K> keyMapper,
        Function<T, V> valueMapper) {
    return entities.stream().collect(Collectors.groupingBy(keyMapper, HashMap::new,
            Collectors.mapping(valueMapper, Collectors.toCollection(HashSet::new))));
}

---

• «
• 1
• 2
• 3
• »