从地图数组中获得唯一的名称和相应的金额和金额

Question

我正在尝试迭代一个数组列表.List<Map<String, Object>> majorList=new ArrayList<Map<String, Object>>();

数据格式将是

1. {“分类账”："A“、"basicAmt"：10、”消费税“：2}、{”分类账“："B”、"exciseAmt"：20、"grossAmt"：3}、{“分类账”："A“、"basicAmt"：30、”消费税“：5}、{”分类账“："C”、"exciseAmt"：50、"grossAmt"：10}、{“分类账”："B“、"basicAmt"：40、”消费税“：8}， 所需的结果如下：

1. {"ledger": "A","basicAmt": 40,"excise": 7}, {"ledger": "B","exciseAmt": 60,"grossAmt": 11}, {"ledger": "C","basicAmt": 50,"excise": 10},

​

Answer 1

这将创建一张地图。最高层的关键是分类账。二级地图将为每种“类型”都有一个键。如果类型不存在，则将创建该类型；如果存在，则会将其添加到现有条目中。最后将结果显示在最后。

    List<Map<String, Object>> majorList = new ArrayList<Map<String, Object>>();

    // setup
    Map<String, Object> map = new HashMap<>();
    map.put("ledger", "A");
    map.put("basicAmt", 10);
    map.put("excise", 2);
    majorList.add(map);

    map = new HashMap<>();
    map.put("ledger", "B");
    map.put("exciseAmt", 20);
    map.put("grossAmt", 3);
    majorList.add(map);

    map = new HashMap<>();
    map.put("ledger", "A");
    map.put("basicAmt", 30);
    map.put("excise", 5);
    majorList.add(map);

    map = new HashMap<>();
    map.put("ledger", "C");
    map.put("exciseAmt", 50);
    map.put("grossAmt", 10);
    majorList.add(map);

    map = new HashMap<>();
    map.put("ledger", "B");
    map.put("basicAmt", 40);
    map.put("excise", 8);
    majorList.add(map);

    Map<String, Map<String, Object>> ledgers = new HashMap<>();

    // iterate through list
    for (Map<String, Object> m : majorList) {

        // get result map and create if does not exist
        String ledger = (String) m.get("ledger");
        Map<String, Object> ledgerMap = ledgers.get(ledger);
        if (ledgerMap == null) {
            ledgerMap = new HashMap<>();
            ledgers.put(ledger, ledgerMap);
        }

        // iterate through map for other keys
        for (Entry<String, Object> entry : m.entrySet()) {
            String key = entry.getKey();
            // ignore ledger key
            if (!key.equals("ledger")) {
                // Add results
                Integer value = (Integer) entry.getValue();
                Integer existing = (Integer) ledgerMap.get(key);
                if (existing == null) {
                    ledgerMap.put(key, value);
                } else {
                    ledgerMap.put(key, existing + value);
                }
            }
        }
    }

    // display results
    for (Entry<String, Map<String, Object>> entry : ledgers.entrySet()) {
        System.out.println("Ledger: " + entry.getKey());
        for (Entry<String, Object> ledgerEntry : entry.getValue()
                .entrySet()) {
            System.out.println("  " + ledgerEntry.getKey() + ": "
                    + ledgerEntry.getValue());
        }
    }

Answer 2

您必须填充一个新的Map，然后根据公共键添加值。经过总结，它更好的有一个Map<String, Object>，因为所有的地图将是为独特的分类账。

    Map<String, Map<String, Object>> sumMap = new HashMap<String, Map<String,Object>>();
    for (Map<String, Object> abc : majorList) {
        Map temp = sumMap.get((String) abc.get("ledger"));
        if (temp == null) {
            sumMap.put((String) abc.get("ledger"), abc);
        } else {
            for (Entry<String, Object> entry : abc.entrySet()) {
                if (!entry.getKey().equals("ledger")) {
                    temp.put(entry.getKey(),
                            (Integer) temp.get(entry.getKey())
                                    + (Integer) entry.getValue());
                }
            }
        }
    }