Question

Let me first show you the xml structure:

<config>

   <engine>
     <eid>1</eid>
     <somechild>text</somechild>
     <somemodechild>
       <subchild>subchbild</subchild>
     <somemorechild>
   </engine>
     <eid>1</eid>
     <somechild>text</somechild>
     <somemodechild>
       <subchild>subchbild</subchild>
     <somemorechild>
   </engine>
   <engine>
     <eid>1</eid>
     <somechild>text</somechild>
     <somemodechild>
       <subchild>subchbild</subchild>
     <somemorechild>
   </engine>
   </engine>
     <eid>1</eid>
     <somechild>text</somechild>
     <somemodechild>
       <subchild>subchbild</subchild>
     <somemorechild>
   </engine>
   <engine>
     <eid>1</eid>
     <somechild>text</somechild>
     <somemodechild>
       <subchild>subchbild</subchild>
     <somemorechild>
   </engine>

</config>

Here <config> is the root element. I have to create a GUI to edit xml element. I have done it, using JSP and have a made a GUI for each <engine> in the same page, go the each user can edit a particular <engine> and then save the <config> elements, and to save the changes to that particular <engine> tag i am using eid to segregate the particular <engine>.

Now, I want to rewrite the particular <engine> being edited in a separate xml file. How can I achieve it using jdom?

Answer 1

Not sure if I correctly understand your requirements:
You have a xml file (file A) above as posted above and another xml file (file B) containing only one engine-node.

If you have a unique ID (eid?) in file A parse it into your DOM and then replace the node where the eid matches the eid in file B.

To find the engine in file A that matches the eid in file B, you could use XPath.

Node aEID = xp.evaluate("/config/engine[eid='3']"); 
Node bEID = docB.getRoot();

then you would remove aEID from your first DOM

docA.remove(aEID);

and add bEID

docA.getRoot().add(bEID);

(the code above is not meant to compile)