Java：从嵌套的HashMap获取数据

Question

嗨伙计我已经看了下面提到问题的答案，但它没有帮助，因为他们给出静态值的答案，而我需要从动态approch获得价值

How to put/get values into/from Nested HashMap

Getting value from Nested HashMap into another Map

How do I access nested HashMaps in Java?

这是我的情景：

这是我从HashMap添加和检索数据的类： -

HashMap<Integer, String> xmlQueryNode = new HashMap<Integer, String>();
HashMap<Integer, HashMap<Integer, String>> splunkHashMap = new HashMap<Integer, HashMap<Integer, String>>();
id = 0;
xmlQueryNode.put(0, "F0name");
xmlQueryNode.put(1, "L0name");
xmlQueryNode.put(2, "M0name");

splunkHashMap.put(id, xmlQueryNode);

id = 1;
xmlQueryNode.put(0, "F1name");
xmlQueryNode.put(1, "L1name");
xmlQueryNode.put(2, "M1name");

splunkHashMap.put(id, xmlQueryNode);

id = 2;
xmlQueryNode.put(0, "F2name");
xmlQueryNode.put(1, "L2name");
xmlQueryNode.put(2, "M2name");

splunkHashMap.put(id, xmlQueryNode);

id = 3;
xmlQueryNode.put(0, "F3name");
xmlQueryNode.put(1, "L3name");
xmlQueryNode.put(2, "M3name");

splunkHashMap.put(id, xmlQueryNode);

for (Integer key : splunkHashMap.keySet()) {
    HashMap<Integer, String> temp =  new HashMap<Integer, String>();
    //System.out.println(key);
    temp = otsdbQueryData.get(key);
    for(Integer key1: temp.keySet()){
        System.out.println(temp.get(key1));
    }
}

此代码的问题在于我得到所有4个条目的输出： -

F3name
L3name
M3name

F3name
L3name
M3name

F3name
L3name
M3name

F3name
L3name
M3name

任何人都可以指出我在哪里犯错误，因为我的哈希映射被最后插入的hashmap覆盖了吗？

Answer 1

在放入内部hashmap之后，您需要重新初始化该地图。

xmlQueryNode = new HashMap<Integer,String>();
xmlQueryNode.put(0, "F1name");
xmlQueryNode.put(1, "L1name");
xmlQueryNode.put(2, "M1name");

否则它将更新相同的参考。

请检查更新的代码。

int id =0;

HashMap<Integer, String> xmlQueryNode = new HashMap<Integer, String>();
HashMap<Integer, HashMap<Integer, String>> splunkHashMap = new HashMap<Integer, HashMap<Integer, String>>();
id = 0;
xmlQueryNode.put(0, "F0name");
xmlQueryNode.put(1, "L0name");
xmlQueryNode.put(2, "M0name");

splunkHashMap.put(id, xmlQueryNode);

xmlQueryNode = new HashMap<Integer, String>();
id = 1;
xmlQueryNode.put(0, "F1name");
xmlQueryNode.put(1, "L1name");
xmlQueryNode.put(2, "M1name");

splunkHashMap.put(id, xmlQueryNode);

xmlQueryNode = new HashMap<Integer, String>();
id = 2;
xmlQueryNode.put(0, "F2name");
xmlQueryNode.put(1, "L2name");
xmlQueryNode.put(2, "M2name");

splunkHashMap.put(id, xmlQueryNode);

xmlQueryNode = new HashMap<Integer, String>();
id = 3;
xmlQueryNode.put(0, "F3name");
xmlQueryNode.put(1, "L3name");
xmlQueryNode.put(2, "M3name");

splunkHashMap.put(id, xmlQueryNode);

for (Integer key : splunkHashMap.keySet()) {
    HashMap<Integer, String> temp =  new HashMap<Integer, String>();
    //System.out.println(key);
    temp = splunkHashMap.get(key);
    for(Integer key1: temp.keySet()){
        System.out.println(temp.get(key1));
    }
}

Answer 2

xmlQueryNode引用被反复覆盖。检查以下代码。

HashMap<Integer, String> xmlQueryNode = new HashMap<Integer, String>();
HashMap<Integer, HashMap<Integer, String>> splunkHashMap = new HashMap<Integer, HashMap<Integer, String>>();
id = 0;
xmlQueryNode.put(0, "F0name");
xmlQueryNode.put(1, "L0name");
xmlQueryNode.put(2, "M0name");

splunkHashMap.put(id, xmlQueryNode);

id = 1;
xmlQueryNode = new HashMap<Integer,String>();
xmlQueryNode.put(0, "F1name");
xmlQueryNode.put(1, "L1name");
xmlQueryNode.put(2, "M1name");

splunkHashMap.put(id, xmlQueryNode);

id = 2;
xmlQueryNode = new HashMap<Integer,String>();
xmlQueryNode.put(0, "F2name");
xmlQueryNode.put(1, "L2name");
xmlQueryNode.put(2, "M2name");

splunkHashMap.put(id, xmlQueryNode);

id = 3;
xmlQueryNode = new HashMap<Integer,String>();
xmlQueryNode.put(0, "F3name");
xmlQueryNode.put(1, "L3name");
xmlQueryNode.put(2, "M3name");

splunkHashMap.put(id, xmlQueryNode);

for (Integer key : splunkHashMap.keySet()) {
    HashMap<Integer, String> temp =  new HashMap<Integer, String>();
    //System.out.println(key);
    temp = otsdbQueryData.get(key);
    for(Integer key1: temp.keySet()){
        System.out.println(temp.get(key1));
    }
}