Java List＜Map＞集合根据相同key分组进行某项数据求和

布满荆棘的人生 2023-09-23 13:40 86阅读 0赞

package com.yt.exam.ctrl;
    
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    
    /**
     * Created by LiYangYong 
     */
    public class test {
        public static void main(String[] args) {
            List<Map<String, Object>> list = new ArrayList<>();
            Map<String, Object> map1 = new HashMap<>();
            map1.put("userId", "120");
            map1.put("value", 111);
            list.add(map1);
    
            Map<String, Object> map2 = new HashMap<>();
            map2.put("userId", "120");
            map2.put("value", 112);
            list.add(map2);
    
            Map<String, Object> map3 = new HashMap<>();
            map3.put("userId", "110");
            map3.put("value", 2022);
            list.add(map3);
    
            Map<String, Object> map4 = new HashMap<>();
            map4.put("userId", "110");
            map4.put("value", 56);
            list.add(map4);
    
    
            Map<String, Object> map5 = new HashMap<>();
            map5.put("userId", "159");
            map5.put("value", 2022);
            list.add(map5);
    
            System.out.println("统计后的数据--->>>"+list);
            //根据userId key 合计value
            Map<String, Map<String, Object>> result = new HashMap<>();
            List<Map<String, Object>>  allList = new ArrayList<>();
            for(Map<String, Object> map : list){
                String newId = map.get("userId").toString();
                Integer value = Integer.parseInt(map.get("value").toString());
                if(result.containsKey(newId)){
                    Integer temp = Integer.parseInt(result.get(newId).get("value").toString());
                    value += temp;
                    result.get(newId).put("value", value);
                    continue;
                }
                result.put(newId, map);
                allList.add(map);
            }
            System.out.println("");
            System.out.println("统计后的数据--->>>"+allList);
        }
    }

测试结果如下：

![6fa3ccc5b850410fa3a525efbc2bb763.png][]

[6fa3ccc5b850410fa3a525efbc2bb763.png]: https://img-blog.csdnimg.cn/6fa3ccc5b850410fa3a525efbc2bb763.png