List集合按照对象属性(多属性拼接)分组并生成自定义对象集合

import lombok.Data;
import lombok.experimental.Accessors;

@Data
@Accessors(chain = true)
public class Student {

    //学生名称
    private String name;
    //年龄
    private Integer age;
    //性别 1 男 2女
    private String sex;

}

import lombok.Data;
import lombok.experimental.Accessors;

@Data
@Accessors(chain = true)
public class StudentData {

    //学生名称
    private String name;
    //年龄
    private Integer age;
    //性别 1 男 2女
    private String sex;

    //班级
    private String classes;

}

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.StrUtil;
import com.alibaba.fastjson.JSON;

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

public class Test {

    public static void main(String[] args) {
        List students = new ArrayList() {{
            add(new Student().setName("张三").setAge(18).setSex("1"));
            add(new Student().setName("李四").setAge(21).setSex("1"));
            add(new Student().setName("丽丽").setAge(18).setSex("2"));
            add(new Student().setName("小美").setAge(23).setSex("2"));
            add(new Student().setName("如花").setAge(23).setSex("2"));
        }};
        Map> ageMap = students.stream().collect(Collectors.groupingBy(Student::getAge, Collectors.mapping(student -> BeanUtil.copyProperties(student, StudentData.class), Collectors.toList())));
        System.err.println(ageMap.toString());
        Map> ageSexMap = students.stream().collect(Collectors.groupingBy(student -> StrUtil.concat(true,String.valueOf(student.getAge()),"-",student.getSex()), Collectors.mapping(student -> BeanUtil.copyProperties(student, StudentData.class), Collectors.toList())));
        System.err.println(ageSexMap.toString());

        List studentDatas = JSON.parseArray(JSON.toJSONString(students), StudentData.class);
        System.err.println(studentDatas.toString());
    }
}

打印1 按照年龄分组并生成自定义对象：
{
18=[StudentData(name=张三, age=18, sex=1, classes=null), StudentData(name=丽丽, age=18, sex=2, classes=null)], 
21=[StudentData(name=李四, age=21, sex=1, classes=null)], 
23=[StudentData(name=小美, age=23, sex=2, classes=null), StudentData(name=如花, age=23, sex=2, classes=null)]
}

打印2 按照年龄和性别分组并生成自定义对象：
{
23-2=[StudentData(name=小美, age=23, sex=2, classes=null), StudentData(name=如花, age=23, sex=2, classes=null)], 
21-1=[StudentData(name=李四, age=21, sex=1, classes=null)], 
18-2=[StudentData(name=丽丽, age=18, sex=2, classes=null)], 
18-1=[StudentData(name=张三, age=18, sex=1, classes=null)]
}

打印3：将集合转为JSON字符串然后再转成自定义集合
[
StudentData(name=张三, age=18, sex=1, classes=null), 
StudentData(name=李四, age=21, sex=1, classes=null), 
StudentData(name=丽丽, age=18, sex=2, classes=null), 
StudentData(name=小美, age=23, sex=2, classes=null), 
StudentData(name=如花, age=23, sex=2, classes=null)
]

       
		
            com.alibaba
            fastjson
            1.2.71
        

		
            cn.hutool
            hutool-all
            5.7.7