HashMap.put无法正常工作

Question

I'm trying to save a HashMap in another hashmap.

The problem comes when I save one key and value in the inner hashmap.

When I try to recover the value, always return null.

It's like HashMap doesnt work... Why??

I try to create a global variable protected and final.. and nothing :(

protected final Map<Integer,Map> HMG =  new HashMap<Integer,Map>(); //GLOBAL VARAIBLE

    List<org.jdom2.Element> hijos = root.getChildren();
    for(int i=0 ; i < hijos.size(); i++) {
        org.jdom2.Element elem = hijos.get(i);
        String file = elem.getName();
        HMG.put(i, new HashMap<String, String>());
        System.out.println("Hashmap saved to "+ i+" "+file );
        System.out.println(file + i);
        List<org.jdom2.Element> hijos2 =elem.getChildren();
        for (org.jdom2.Element e : hijos2){
            guardarAtributos(e,i);
        }
    }

public void guardarAtributos(org.jdom2.Element elemento,Integer orden) {
    List<org.jdom2.Attribute> atributos=elemento.getAttributes();
     Map<String,String> a =HMG.get(orden);
     for (org.jdom2.Attribute atrib : atributos) {
         a.put(atrib.getName(), atrib.getValue());
         System.out.println("Writting into miniHashMap ===> "+atrib.getName()+" "+" "+atrib.getValue());
         System.out.println("Testing:::::"+ a.get(0));
    }
}

The output is:

Hashmap saved to 0 Number
Number0
Writting into miniHashMap ===> value  3
Testing:::::null
Writting into miniHashMap ===> value  1
Testing:::::null
Writting into miniHashMap ===> value  4
Testing:::::null
Hashmap saved to 1 Number
Number1
Writting into miniHashMap ===> value  88
Testing:::::null

Edit!: Thanks you, but when im triying to recover a value, using

public void recuperarHashMap(Integer orden){
 Map<String,String> hash= HMG.get(orden);
 for(Entry<String, String> entry: hash.entrySet()) {
     System.out.println(entry.getKey());
     System.out.println(entry.getValue());
 }
}

Test Class:

a.recuperarHashMap(0);
a.recuperarHashMap(1);

Output:

value
4
value
88

I only get the last value!! why?!!! Thanks you a lot :) im a noob! :(

Edit2 !!

The XML is like that (made with emf tool editor)

<?xml version="1.0" encoding="UTF-8"?>
<xmi:XMI xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:language1="language1">
  <language1:Number id="PI">
    <has value="3"/>
    <has value="1"/>
    <has value="4"/>
  </language1:Number>
  <language1:Number id="888">
    <has value="88"/>
  </language1:Number>
</xmi:XMI>

Answer 1

You're not testing for the same thing you're putting in:

a.put(atrib.getName(), atrib.getValue());
...
System.out.println("Testing:::::"+ a.get(0));

atrib.getName() isn't the number 0, is it? If you change your code to:

System.out.println("Testing:::::"+ a.get(atrib.getName()));

you'll find it can recover the value with no problems. What did you expect a.get(0) to do? Were you perhaps expecting it to return the first element within the map? Maps don't work like that - the get() method fetches by key .

EDIT: If you're setting multiple entries with a key of value , that suggests you've got multiple attributes with a name of value . Note that you've got two loops:

for (org.jdom2.Element e : hijos2){
    guardarAtributos(e,i);
}

and:

for (org.jdom2.Attribute atrib : atributos) {
    a.put(atrib.getName(), atrib.getValue());
    ...
}

So if you've got multiple elements all with a value attribute then yes , the earlier values will be overwritten by the later ones.

I suspect you have XML like this:

<root>
  <child>
    <x value="3" />
    <y value="1" />
    <z value="4" />
  </child>
  <child>
    <x value="88" />
  </child>
</root>  

... but you haven't shown us your XML, so we can't really say for certain.

EDIT: Now that we've seen your XML, it's not clear why you're using the attribute name at all, or why you want maps at all. It looks to me like you really want a List<List<String>> :

List<List<String> elementValues = new ArrayList<List<String>>();

List<Element> elements = root.getChildren();
for (Element element : elements) {
    List<String> values = new ArrayList<String>();
    for (Element child : element.getChildren()) {
        values.add(child.getAttributeValue("value"));
    }
}

This will be much simpler than using maps etc.

Answer 2

最终的杂音不能覆盖