help , Concurrent Modification Exception

[Hussein Baghdadi]

Hi all.
I have the following XML file :

  
<?xml version="1.0" encoding="UTF-8"?>
<downloads>
<nof>2</nof>
<download>
<url>http://localhost</url>
<size>4550434</size>
<progress>55</progress>
<status>resume</status>
</download>
<download>
<url>http://somedomain</url>
<size>34343434</size>
<progress>55</progress>
<status>cancel</status>
</download>
</downloads>

I am using JDOM 9 , I want to search for download element which its url subelement is equal to http://localhost and delete it.
this is the code :

  
SAXBuilder builder = new SAXBuilder();
Document doc = builder.build(new File("F:\\download.xml"));
Element root = (Element) doc.getRootElement( );
List childrens = root.getChildren("download");
Iterator it = childrens.iterator( );
while (it.hasNext( )) {
       Element download = (Element) it.next( );
       if (download.getChild("url").getText( ).equals("http://localhost"))
           root.removeContent(download);
}

I got the exception :
java.util.ConcurrentModificationException
any help ???
thanks...

[Lasse Koskela]

You can't remove items from a Collection you're iterating and then just continue iterating.

[Hussein Baghdadi]

Thanks.
would you suggest a solution for my problem ??

[Lasse Koskela]

You could iterate through all the nodes, add those you want to remove into a separate collection, and afterwards, iterator through that other collection calling remove() on each of them.

Here's what I mean in pseudo code:

Node root = ...
List nodesToRemove
loop: for each child element of root
    if child should be removed
        add child to nodesToRemove
end loop
loop: for each element in nodesToRemove
    root.remove(element)
end loop

[Lasse Koskela]

Oh, and another option could be to access the nodes using an index like this:

Node root = ...;
NodeList children = root.getElementsByTagName("download");
for (int i = 0; i < children.getLength(); i++) {
    Node child = children.item(i);
    if (<child needs to be removed>) {
        root.removeChild(child);
        // you might need to also decrement 'i' here
        // in order to avoid skipping child elements
    }
}