如何将一个哈希映射列表中的不同值添加到另一个哈希映射列表中

Question

有人能帮我找到一份没有重复的正确清单吗。

我有一个哈希映射列表，比如“HashMap map”，它的大小是4。键值对类似于以下内容

("uri_path","/shophome/index")
("AvgResp","30.00")
("count", "3");
("status","200");

我想创建另一个Hashmap列表，其中包含“uri\u path”的单个条目以及相应计算的平均值和计数。这就是我正在尝试的。理想情况下，新列表的大小应小于原始列表的大小。有人能帮我理解是不是出了问题

HashMap<String, String> processedMap = null;
        List<HashMap<String, String>> artProcessedEvents=new ArrayList<HashMap<String, String>>();
        for (HashMap<String, String> map : artEvents) {// list that contains the values
            processedMap = new HashMap<String, String>();

            String uri_path= map.get("uri_path");
            Double art = Double.parseDouble(map.get("avgRespT"));   
            count =Integer.parseInt(map.get("count"));



            if (processedMap.containsValue(uri_path)){

                Double artFromMap = Double.parseDouble(processedMap.get("avgRespT"));
                int countFromMap =Integer.parseInt(processedMap.get("count"));
                count = count+countFromMap;
                art = ((art*count) + (artFromMap*countFromMap))/count;

            }

            processedMap.put("uri_path",uri_path);
            processedMap.put("avgRespT",String.valueOf(art));
            processedMap.put("count", String.valueOf(count));
            artProcessedEvents.add(processedMap);
            }
        }

Answer 1

你似乎很困惑，但这会有所帮助。

为了删除重复项并更新参数，您需要从简单字符串更改processedmap-

 HashMap<String, HashMap<String, String>> processedMap = new HashMap<String, HashMap<String, String>>();
        List<HashMap<String, String>> artProcessedEvents=new ArrayList<HashMap<String, String>>();
        for (HashMap<String, String> map : artEvents) {// list that contains the values


            String uri_path= map.get("uri_path");
            Double art = Double.parseDouble(map.get("avgRespT"));   
            count =Integer.parseInt(map.get("count"));



            if (processedMap.containsValue(uri_path)){

                Double artFromMap = Double.parseDouble(processedMap.get("avgRespT"));
                int countFromMap =Integer.parseInt(processedMap.get("count"));
                count = count+countFromMap;
                art = ((art*count) + (artFromMap*countFromMap))/count;

            }
           //Create a new Hashmap 
             HashMap<String, String> updatedMap=new HashMap<String, String>();
            updatedMap.put("uri_path",uri_path);
            updatedMap.put("avgRespT",String.valueOf(art));
            updatedMap.put("count", String.valueOf(count));
            processedMap.put(uri_path,updateMap);

            }
            //Iterate and add elements to the list
              for (Map.Entry<String, HashMap<String, String>> entry : processedMap.entrySet())
             {
               artProcessedEvents.add(entry.getValue());
             }


        }

Answer 2

问题是，

if (processedMap.containsValue(uri_path)){

    Double artFromMap = Double.parseDouble(processedMap.get("avgRespT"));
    int countFromMap =Integer.parseInt(processedMap.get("count"));
    count = count+countFromMap;
    art = ((art*count) + (artFromMap*countFromMap))/count;

}

您必须从“map”（for循环变量）中获取值并对其进行操作。并且processedMap对于每次运行都将为空，并且需要删除。

Answer 3

请尝试以下代码：

List<HashMap<String, String>> artEvents = ...;

//this map stores all of the result maps (one map per uri_path, uri_path is the key in this uniqueUriMap, map itself being a value).
HashMap<String, HashMap<String, String>> uniqueUriMap = new HashMap<String, HashMap<String, String>>(); 

for (HashMap<String, String> mapBeingProcessed : artEvents) 
{
    String uri_path = mapBeingProcessed.get("uri_path");
    Double art = Double.parseDouble(mapBeingProcessed.get("avgRespT"));   
    Integer count =Integer.parseInt(mapBeingProcessed.get("count"));

    if (uniqueUriMap.containsKey(uri_path)) 
    {
        Double artFromMap = Double.parseDouble(uniqueUriMap.get(uri_path).get("avgRespT"));
        int countFromMap = Integer.parseInt(uniqueUriMap.get(uri_path).get("count"));
        count = count + countFromMap;
        art = ((art * count) + (artFromMap * countFromMap)) / count;
    }

    HashMap<String, String> newUriMap = new HashMap<String, String>();
    newUriMap.put("uri_path",uri_path);
    newUriMap.put("avgRespT",String.valueOf(art));
    newUriMap.put("count", String.valueOf(count));
    uniqueUriMap.put(uri_path, newUriMap);
}
//result list.
List<HashMap<String, String>> artProcessedEvents=new ArrayList<HashMap<String, String>>();
artProcessedEvents.addAll(uniqueUriMap.values());

问题是存储临时值。这：

if (processedMap.containsValue(uri_path))

在循环内初始化processedMap时始终返回false。