没描述,直接看结果吧。
- package com.anchnet.sync;
-
- import cn.hutool.json.JSONUtil;
- import lombok.AllArgsConstructor;
- import lombok.Data;
- import lombok.NoArgsConstructor;
- import lombok.extern.slf4j.Slf4j;
-
- import java.util.LinkedList;
- import java.util.List;
- import java.util.Map;
- import java.util.stream.Collectors;
-
- /**
- * @author H.Yang
- * @date 2021/11/19
- */
- @Slf4j
- public class AppDemo {
-
- public static void main(String[] args) {
- List
list = new LinkedList<>(); -
- list.add(new Student("A1", "男", 10001));
- list.add(new Student("A2", "女", 10002));
- list.add(new Student("A3", "男", 10002));
- list.add(new Student("A4", "女", 10001));
- list.add(new Student("A5", "男", 10003));
-
- // 核心代码
- Map
> map = list.stream().collect(Collectors.groupingBy(item -> item.getTeacherId(), Collectors.mapping(item -> item, Collectors.toList()))); -
- System.out.println(JSONUtil.toJsonStr(map));
- }
-
- }
-
- @Data
- @NoArgsConstructor
- @AllArgsConstructor
- class Student {
- private String name;
- private String sex;
- private Integer teacherId;
- }
结果
- {
- "10002": [
- {
- "sex": "女",
- "teacherId": 10002,
- "name": "A2"
- },
- {
- "sex": "男",
- "teacherId": 10002,
- "name": "A3"
- }
- ],
- "10001": [
- {
- "sex": "男",
- "teacherId": 10001,
- "name": "A1"
- },
- {
- "sex": "女",
- "teacherId": 10001,
- "name": "A4"
- }
- ],
- "10003": [
- {
- "sex": "男",
- "teacherId": 10003,
- "name": "A5"
- }
- ]
- }