映射的组和聚合列表

Question

我有一个列表 >输入，如下所示：

[{
    CURRENCY = USD,
    STATUS = NEW,
    PUBLISH_REGION = DEL,
    SOURCE = ALADDIN,
    RECON_STATUS = null,
    JOB_ID_COUNT = 783
}, {
    CURRENCY = USD,
    STATUS = IN_PROGRESS,
    PUBLISH_REGION = DEL,
    SOURCE = ALADDIN,
    RECON_STATUS = null,
    JOB_ID_COUNT = 462
}, {
    CURRENCY = USD,
    STATUS = NEW,
    PUBLISH_REGION = DEL,
    SOURCE = GROUP,
    RECON_STATUS = null,
    JOB_ID_COUNT = 4
}]

我试图通过对CURRENCY、PUBLISH_REGION、SOURCE和RECON_STATUS列进行分组来创建另一个列表 >。并将所有唯一状态值作为数据透视添加到输出映射中,并使用JOB_ID_COUNT汇总/聚合计数。

List<String> groups = new ArrayList<>(asList("SOURCE", "RECON_STATUS", "PUBLISH_REGION", "CURRENCY"));
List<Map<String, Object>> = input.stream()
    .collect(groupingBy(row -> row.get(groups.get(0)), mapping(map -> map.get(groups.get(0)), toList())));

我期待以下响应：输出：

 [{
        CURRENCY = USD,
        PUBLISH_REGION = DEL,
        SOURCE = ALADDIN,
        RECON_STATUS = null,
        NEW = 783,
        IN_PROGRESS = 462
    }, {
        CURRENCY = USD,
        PUBLISH_REGION = DEL,
        SOURCE = GROUP,
        RECON_STATUS = null,
        NEW = 4,
        IN_PROGRESS = 0
    }]

尝试按多个映射字段分组时，我遇到编译时错误。单字段groupingBy工作正常。任何帮助都是非常有效的。

Answer 1

不使用自定义类

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MultipleFieldSorting2 {
    private static Map<String, Object> map, map1, map2;
    private static List<Map<String, Object>> lst = new ArrayList<>();
    static {
        map = new HashMap<>();
        map.put("CURRENCY", "USD");
        map.put("STATUS", "NEW");
        map.put("PUBLISH_REGION", "DEL");
        map.put("SOURCE", "ALADDIN");
        map.put("RECON_STATUS", null);
        map.put("JOB_ID_COUNT", "783");

        map1 = new HashMap<>();
        map1.put("CURRENCY", "USD");
        map1.put("STATUS", "IN_PROGRESS");
        map1.put("PUBLISH_REGION", "DEL");
        map1.put("SOURCE", "ALADDIN");
        map1.put("RECON_STATUS", null);
        map1.put("JOB_ID_COUNT", "462");

        map2 = new HashMap<>();
        map2.put("CURRENCY", "USD");
        map2.put("STATUS", "NEW");
        map2.put("PUBLISH_REGION", "DEL");
        map2.put("SOURCE", "GROUP");
        map2.put("RECON_STATUS", null);
        map2.put("JOB_ID_COUNT", "4");

        lst.add(map);
        lst.add(map1);
        lst.add(map2);
    }
    
    public static Map<String, Object> mapper(Map<String, Object> e){

        String key = e.get("CURRENCY") + "-" + e.get("PUBLISH_REGION") + "-" + e.get("SOURCE") + "-" + e.get("RECON_STATUS");
        Map<String, Object> groupedValue = res.get(key);
        if(groupedValue!=null){
            groupedValue.put((String) e.get("STATUS"), groupedValue.get("STATUS")!=null ? groupedValue.get("STATUS")+","+e.get("JOB_ID_COUNT") : e.get("JOB_ID_COUNT"));
            if(groupedValue.get("NEW")==null){
                groupedValue.put("NEW", 0);
            }
            if(groupedValue.get("IN_PROGRESS")==null){
                groupedValue.put("IN_PROGRESS", 0);
            }
        }else{
            groupedValue = new HashMap<>();
            res.put(key, groupedValue);
            groupedValue.put("CURRENCY", e.get("CURRENCY"));
            groupedValue.put("PUBLISH_REGION", e.get("PUBLISH_REGION"));
            groupedValue.put("SOURCE", e.get("SOURCE"));
            groupedValue.put("RECON_STATUS", e.get("RECON_STATUS"));
            groupedValue.put((String) e.get("STATUS"), e.get("JOB_ID_COUNT"));
        }
        return groupedValue;
    
    }
    static Map<String, Map<String, Object>> res = new HashMap<>();
    
    public static void main(String[] args) {
        List<Map<String, Object>> finalResult = new ArrayList<>();
        lst.stream()
        .map(MultipleFieldSorting2::mapper)
        .forEach(result -> {
            if(!finalResult.contains(result))
                finalResult.add(result);
        });

        System.out.println(finalResult);
    }

}