在Java中使用收集器将流分割成基于类的列表

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

public class Main {
    public static void main(String[] args) {
        // 示例数据
        List<Student> students = Arrays.asList(
                new Student("Alice", "Math"),
                new Student("Bob", "English"),
                new Student("Charlie", "Math"),
                new Student("David", "Physics"),
                new Student("Emma", "English")
        );

        // 将学生按照所学科目分组
        Map<String, List<Student>> groupedStudents = students.stream()
                .collect(Collectors.groupingBy(student -> student.getSubject()));

        // 输出分组结果
        for (Map.Entry<String, List<Student>> entry : groupedStudents.entrySet()) {
            String subject = entry.getKey();
            List<Student> studentsInSubject = entry.getValue();
            System.out.println(subject + ": " + studentsInSubject);
        }
    }
}

class Student {
    private String name;
    private String subject;

    public Student(String name, String subject) {
        this.name = name;
        this.subject = subject;
    }

    public String getName() {
        return name;
    }

    public String getSubject() {
        return subject;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                '}';
    }
}

Physics: [Student{name='David'}]
English: [Student{name='Bob'}, Student{name='Emma'}]
Math: [Student{name='Alice'}, Student{name='Charlie'}]