JAXB - complex hashmap

[igor kvak]

Hi,
Hi,
I am quite new to JAXB and I have a following problem:

I want to marshall this class:

class A{
 String id; //unique
 HashMap<A,A> map;
}

I am getting cyclic reference exception

could you please help me or give me any hint?
thanks a lot

[Paul Clapham]

I can't even imagine why you would want to have such a class, let alone marshal it to XML. However... can you give an example of what the marshalled XML would look like for a typical element of that class?

[igor kvak]

Paul Clapham wrote:I can't even imagine why you would want to have such a class, let alone marshal it to XML.

implementing routing table - key is destination router, value is next-hop router; and the class is router itself - I know that it is quite an unusual data structure...

Paul Clapham wrote:However... can you give an example of what the marshalled XML would look like for a typical element of that class?

this would represent class A, where id=1 and map contains two entries:
key - object A with id 1; value = object A with id 2
key - object A with id 2; value = object A with id 3
<node> <id>1</id> <map> <entry> <value>1</value> <key>2</key> </entry> <entry> <value>2</value> <key>3</key> </entry> </map> </node>

so when marshalling HashMap, IDs will be used instead of real objects and when unmarshalling, IDs will be replaced with related objects

[Paul Clapham]

I see. So you really don't want

    class A{  
     String id; //unique  
     HashMap<A,A> map;  
    }  

but instead you want

    class A{  
     String id; //unique  
     HashMap<key,value> map;  
    }  

[igor kvak]

no
I really need
HashMap<A,A> because key and value are the same type as the class itself - once again: "key is destination router, value is next-hop router; and the class is router itself"

the problem is not how to marshall HashMap, but how to marshall hashmap that has cyclic referencies, e.g.:
A a1 = new A();
A a2 = new A();

map.put(a1,a1);
map.put(a2,a1);

[Paul Clapham]

igor kvak wrote:no
I really need
HashMap<A,A> because key and value are the same type as the class itself - once again: "key is destination router, value is next-hop router; and the class is router itself"

But that wasn't what your XML example showed. So try again to show an example where your <Router> element has descendant elements which are also <Router> elements.

[igor kvak]

well, if I use <Router> elements as children of root <Router> that would be cyclic reference, but I want to avoid that so instead of child <Router> elements, only IDs of these elements will be used - just like my example XML (maybe I should mentioned, that those numbers in <key> and <value> elements are router IDs, my bad...)