Question

我试图根据从查询中获得的结果集来创建树结构。仅当结果集有两列时，下面的代码块才有效。第一列是父列，第二列是子列。我遇到的问题是尝试对其进行重新设计，以便它可以包含多个不同的级别（每列代表一个级别）。我现在唯一能做的就是复制代码，检查级别数和硬编码以便添加到新级别。我按行然后列处理结果集。（例如，获取第一行，然后获取第一列并存储该值。）

有关如何重新设计此功能的任何想法，可以灵活调整其可以达到的级别数量吗？最终，根被传递到HashTable并处理为JSON文件。仅供参考，我在代码的第二部分中进行JSON格式化，遍历HashMap并对其进行格式化以适应我对JSON的需求。

    HashMap<String, HashSet<String>> level1TwoColumn = new HashMap<String, HashSet<String>>();

    Object[] listElementCalcColumnNumber = list.get(0);

    Hashtable allHash = new Hashtable();

        //this will store all of the values in a hashmap and hashset
        for(int i=0; i<list.size(); i++){
            Object[] listElement = list.get(i);

            //the reason we added ""+ between (String) and listElement is because listElement can be something other than a String (e.g. double, integer, etc)
            //by adding "" to it, it becomes a String value automatically so then we can cast double/integer/etc into a String
            String currentLevel1 = (String) ""+listElement[0];
            currentLevel1 = currentLevel1.replace("\"", "");
            //this prevents variables from duplicating. if the new element does not exist in hashmap, a new record in the hashmap will be created.
            if((level1TwoColumn.get(currentLevel1) = null)){
                HashSet<String> level2 = new HashSet<String>();

                level1TwoColumn.put(currentLevel1, level2);
            }

            //stores all of the lowest level into a hashset because they're all going to be unique. no need to check to see if they exist in the hashset.
            String currentLevel2 = (String) ""+listElement[1];
            currentLevel2 = currentLevel2.replace("\"", "");

            level1TwoColumn.get(currentLevel1).add(currentLevel2);
        }

        HashSet completeTree = new HashSet();

        //now that the structure of the data is complete. iterate through level1 to get and store keys as values and "name" as key
        for(String key1 : level1TwoColumn.keySet()){
            HashSet levelOneSet = new HashSet();

            HashMap levelOne = new HashMap();

            levelOne.put("name", key1);
            levelOneSet.add(levelOne);

            //this for-statement does the same thing as previous for-statement; stores the unique values and give them "name" and then put them in hashset and give the set a "children" key
            for(String key2 : level1TwoColumn.get(key1)){
                HashSet levelTwoSet = new HashSet();

                HashMap levelTwo = new HashMap();
                levelTwo.put("name", key2);
                levelTwoSet.add(levelTwo);

                levelOne.put("children", levelTwoSet);
            }

            //once it loops through once, all level 2 items will be stored under a unique level 1. then it gets added into our dendrogram one by one until all level 1 elements are added.
            completeTree.add(levelOne);
        }

        //this is assigning what our first node is, which is "VA"
        allHash.put("name", "VA");
        //put everything under "VA" node
        allHash.put("children", completeTree);

HashMap中的树数据结构

0 个答案: