java 对象集合补全缺失的月份(折线统计图计算12个月的数据分布)

1、前端显示数据的格式

2.后台通过查询计算得到的数据

3.补全缺失的月份，值赋0就可以

4.代码
实体：

@Data
@AllArgsConstructor
@NoArgsConstructor
public class DataTrans{
    private String name;

    private double value;
}

工具类：

public class SupplementDateUtil {

    public static final String[] monthAndDay = new String[]{"01","02","03","04","05","06","07","08","09","10","11","12"};

    public static List supplementDate(List params){

        List list = new ArrayList<>();
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(new Date());
        //当前年份
        int year = calendar.get(Calendar.YEAR);
        for (DataTrans data:params){
            list.add(data);
            for (String s:monthAndDay){
                DataTrans dataTrans = new DataTrans();
                String date = year+"-"+s;
                if (!date.equals(data.getName())){
                    dataTrans.setName(date);
                    dataTrans.setValue(0);
                    list.add(dataTrans);
                }
            }
        }
        // 集合中相同属性去重、值合并
        return RemovalData.merge(list);
    }



    public static void main(String[] args) {

        DataTrans dataTrans = new DataTrans("2021-08",0.05);
        DataTrans dataTrans1 = new DataTrans("2021-05",0.8);
        DataTrans dataTrans2 = new DataTrans("2021-05",0.8);
        DataTrans dataTrans3 = new DataTrans("2021-11",0.86);
        List list = new ArrayList<>();
        list.add(dataTrans);
        list.add(dataTrans1);
        list.add(dataTrans2);
        list.add(dataTrans3);
        List list1 = supplementDate(list);
        //根据月份升序排序
        Collections.sort(list1, Comparator.comparing(DataTrans::getName,(t1, t2) -> t1.compareTo(t2)));
        System.out.println(list1);
    }
}

去重合并属性值工具类

mport com.cust.bigdatacollection.entity.DataTrans;

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

public class RemovalData {

    public static List merge(List list) {
        List result = list.stream()
                // 表示name为key，接着如果有重复的，那么从DataTrans对象o1与o2中筛选出一个，这里选择o1，
                // 并把name重复，需要将value与o1进行合并的o2, 赋值给o1，最后返回o1
                .collect(Collectors.toMap(DataTrans::getName, a -> a, (o1, o2)-> {
                    o1.setValue(o1.getValue() + o2.getValue());
                    return o1;
                })).values().stream().collect(Collectors.toList());
        return result;
    }
}

5.结果