java实现将list中对象的省市区个数和名称统计成 List<Map<String,List<Map<String,List<Map<String,Object>>>>>>结构

可以使用Java的Stream流和Map集合来实现将List中对象的省市区个数和名称统计成List<Map<String,List<Map<String,List<Map<String,Object>>>>>>结构。下面是一个示例代码：

import java.util.*;
import java.util.stream.Collectors;

public class ListToNestedMapExample {
    public static void main(String[] args) {
        // 假设有一个包含省市区信息的对象列表
        List<Address> addressList = Arrays.asList(
                new Address("省1", "市1", "区1"),
                new Address("省1", "市1", "区2"),
                new Address("省1", "市2", "区3"),
                new Address("省2", "市3", "区4"),
                new Address("省2", "市3", "区5")
        );

        // 使用Stream流和Collectors工具类进行统计
        List<Map<String, List<Map<String, List<Map<String, Object>>>>>>> result = addressList.stream()
                .collect(Collectors.groupingBy(Address::getProvince,
                        Collectors.groupingBy(Address::getCity,
                                Collectors.groupingBy(Address::getDistrict))))
                .entrySet().stream()
                .map(provinceEntry -> {
                    Map<String, List<Map<String, List<Map<String, Object>>>>> provinceMap = new HashMap<>();
                    provinceMap.put(provinceEntry.getKey(), provinceEntry.getValue().entrySet().stream()
                            .map(cityEntry -> {
                                Map<String, List<Map<String, Object>>> cityMap = new HashMap<>();
                                cityMap.put(cityEntry.getKey(), cityEntry.getValue().entrySet().stream()
                                        .map(districtEntry -> {
                                            Map<String, Object> districtMap = new HashMap<>();
                                            districtMap.put("name", districtEntry.getKey());
                                            districtMap.put("count", districtEntry.getValue().size());
                                            return districtMap;
                                        })
                                        .collect(Collectors.toList()));
                                return cityMap;
                            })
                            .collect(Collectors.toList()));
                    return provinceMap;
                })
                .collect(Collectors.toList());

        // 输出结果
        for (Map<String, List<Map<String, List<Map<String, Object>>>>> provinceMap : result) {
            for (Map.Entry<String, List<Map<String, List<Map<String, Object>>>>> provinceEntry : provinceMap.entrySet()) {
                System.out.println(provinceEntry.getKey() + ":");
                for (Map<String, List<Map<String, Object>>> cityMap : provinceEntry.getValue()) {
                    for (Map.Entry<String, List<Map<String, Object>>> cityEntry : cityMap.entrySet()) {
                        System.out.println("\t" + cityEntry.getKey() + ":");
                        for (Map<String, Object> districtMap : cityEntry.getValue()) {
                            System.out.println("\t\t" + districtMap.get("name") + " - count: " + districtMap.get("count"));
                        }
                    }
                }
            }
        }
    }

    static class Address {
        private String province;
        private String city;
        private String district;

        public Address(String province, String city, String district) {
            this.province = province;
            this.city = city;
            this.district = district;
        }

        public String getProvince() {
            return province;
        }

        public String getCity() {
            return city;
        }

        public String getDistrict() {
            return district;
        }
    }
}

这段代码会将对象列表中的省市区信息按照指定的结构统计并输出。你可以根据需要对结果进行进一步处理或使用。