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

Question

有人可以帮助我获得正确的列表，没有重复。

我有一个哈希映射列表，说“哈希映射映射”，其大小为 4。 键值对类似于下面的内容

("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_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，新列表的大小应该小于原始列表。有人可以帮助理解它是否出错了

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

试试这个代码：

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());

问题在于存储临时值。这个：

if (processedMap.containsValue(uri_path))

当您在循环内初始化处理映射时，总是返回 false。

Answer 2

问题来了，

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。而且每次运行时也处理过的Map 将是空的，需要将其删除。

Answer 3

您似乎在这里很困惑，但这会有所帮助。

为了删除重复项并更新您的参数，您需要将处理的映射从一个简单的字符串->字符串哈希映射更改为一个字符串->哈希映射，即如下所示。之后您需要通过一个将其添加到列表中迭代器。

 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 4

感谢 Michal 和其他人的建议

下面的代码解决了我的问题

List<HashMap<String, String>> artEvents =new ArrayList<HashMap<String, String>>();
//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());