java - 从列表生成列表

Question

我一直在四处寻找，但找不到一种拆分列表的聪明方法。

假设我们有以下示例:

public class Person {
    private String name;
    private int age;
    private String gender;

    public Person(String name, int age, String gender) {
        this.name = name;
        this.age = age;
        this.gender = gender;
    }

    // Getters/setters
}

那么我有:

List<Person> personList = new ArrayList<>();
personList.add(new Person("Adam", 30, "male"));
personList.add(new Person("John", 32, "male"));
personList.add(new Person("Monica", 30, "female"));
personList.add(new Person("Sophia", 20, "female"));
personList.add(new Person("Carol", 25, "female"));

有没有一种方法可以使用 Stream API 将男性和女性分组生成两个新的人员列表？

Answer 1

抱歉这么短，但我正在回家的火车上。

Map<String, List<Person>> map = list.stream()
    .collect(Collectors.groupingBy(Person::getGender));

代码

public class Person {
    private String name;
    private int age;
    private String genre;
 
    public Person(String name, int age, String genre) {
        this.name = name;
        this.age = age;
        this.genre = genre;
    }

    // getters and setters
}

public class GroupBy {

    public static void main(String[] args) {

        List<Person> list = ArrayList();

        list.add(new Person("Adam", 30, male));
        list.add(new Person("John", 32, male));
        list.add(new Person("Monica", 30, female));
        list.add(new Person("Sophia", 20, female));
        list.add(new Person("Carol", 25, female));

        Map<String, List<Person>> map = list.stream()
            .collect(Collectors.groupingBy(Person::getGender));
    }
}