如果键已经存在，则递归增加相同的嵌套映射值

Question

我的 parentMap 看起来像下面的东西。

HashMap<String, Integer>>> parentMap = {disabled={account={test1=22}, group={test2=10}}}

我想做的是，如果 operationType=disabled 和 objectType=account 或 group 等和 testName=test1 或 test2 等，那么我想增加test1 计数 1.

我必须更新同一张地图，这样最后我应该得到一些统计数据，比如有 22 tests 个 objectType=account 案例和 10 tests 个 [=22] 案例=]等被禁用

我尝试了下面的方法，但它进入了无限循环，因为我将值放入地图并再次对其进行迭代。

private HashMap<String, HashMap<String, HashMap<String, Integer>>> countTags(String statType, String objectType,
            String opType, HashMap<String, HashMap<String, HashMap<String, Integer>>> parentMap) {
        if (!Util.isEmpty(parentMap)) {

            //created new map to avoid infinite loop here but no luck :(

            HashMap<String, HashMap<String, Integer>> objMap = new HashMap<>();
            objMap.putAll(parentMap.get(statType));

            Iterator<Entry<String, HashMap<String, Integer>>> it = objMap.entrySet().iterator();
            while (it.hasNext()) {

                Entry<String, HashMap<String, Integer>> operationEntry = it.next();
                HashMap<String, Integer> operationMap = operationEntry.getValue();
                Set<String> opKeySet = operationMap.keySet();
                Iterator<String> opIt = opKeySet.iterator();

                while (opIt.hasNext()) {
                    parentMap.put(statType, countTags(objectType, opType, operationMap));
                }
            }
        } else {
            parentMap.put(statType, countTags(objectType, opType, new HashMap<String, Integer>()));
        }
        return parentMap;
    }

    private HashMap<String, HashMap<String, Integer>> countTags(String objectType, String opType, HashMap<String, Integer> tagMap) {
        int testRepeatCount = tagMap.get(opType) != null ? tagMap.get(opType) : 0;
        tagMap.put(opType, 1 + testRepeatCount);
        HashMap<String, HashMap<String, Integer>> objMap = new HashMap<>();
        objMap.put(objectType, tagMap);
        return objMap;
    }

我找到了 a.compute(key, (k, v) -> v == null ? 1 : v + 1); 这里也有一些建议 Java map.get(key) - automatically do put(key) and return if key doesn't exist? 但我能得到一些帮助吗？我应该如何以最佳方式在这里实现我想要的结果？

Answer 1

我终于摆脱了自己的 if_else 烂摊子。这就是我的最终方法的样子。这对我有帮助

private HashMap<String, HashMap<String, HashMap<String, Integer>>> countTags(String statType, String objectType,
        String opType, HashMap<String, HashMap<String, HashMap<String, Integer>>> parentMap) {
    if (!Util.isEmpty(parentMap) && parentMap.containsKey(statType)) {
        // if objType is present, count the tags
        if (parentMap.get(statType).containsKey(objectType)) {
            HashMap<String, Integer> objMap = parentMap.get(statType).get(objectType);
            HashMap<String, Integer> map = countTags(objectType, opType, objMap).get(objectType);
            parentMap.get(statType).get(objectType).putAll(map);
        } else {
            // if objType isn't present, add that objType and count the tags
            HashMap<String, HashMap<String, Integer>> map = countTags(objectType, opType,
                    new HashMap<String, Integer>());
            parentMap.get(statType).put(objectType, map.get(objectType));
        }
    } else {
        // first time add the new tag to calculate it's object/operation wise
        // distribution
        parentMap.put(statType, countTags(objectType, opType, new HashMap<String, Integer>()));
    }
    return parentMap;
}

如果键已经存在，则递归增加相同的嵌套映射值

Recursively increase the same nested map values if keys are already exists

java

data-structures

collections

recursive-datastructures