在多个字段上使用groupingBy条件后获取计数

import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

public class GroupingByCountExample {
    public static void main(String[] args) {
        // 示例数据集合
        List<Person> persons = Arrays.asList(
                new Person("Alice", "Engineer"),
                new Person("Bob", "Engineer"),
                new Person("Charlie", "Manager"),
                new Person("Alice", "Manager"),
                new Person("Bob", "Engineer")
        );

        // 在多个字段上使用groupingBy条件后获取计数
        Map<List<String>, Long> countByFields = persons.stream()
                .collect(Collectors.groupingBy(
                        person -> Arrays.asList(person.getName(), person.getRole()),
                        Collectors.counting()
                ));

        // 输出计数结果
        countByFields.forEach((fields, count) -> {
            System.out.println("Fields: " + fields + ", Count: " + count);
        });
    }

    static class Person {
        private String name;
        private String role;

        public Person(String name, String role) {
            this.name = name;
            this.role = role;
        }

        public String getName() {
            return name;
        }

        public String getRole() {
            return role;
        }
    }
}