Help with using getLastChild() method with DOM

Question

Hello all,
I have a XML doc that looks like this:
<?xml version="1.0"?>
<conf_rooms>
<conf_room>
<conf_id>8200</conf_id>
<conf_name>Conf 1</conf_name>
</conf_room>
<conf_room>
<conf_id>8201</conf_id>
<conf_name>Conf 2</conf_name>
</conf_room>
<conf_room>
<conf_id>8202</conf_id>
<conf_name>Conf 3</conf_name>
</conf_room>
<conf_room>
<conf_id>8203</conf_id>
<conf_name>Conf 4</conf_name>
</conf_room>
<conf_room>
<conf_id>8204</conf_id>
<conf_name>Conf 5</conf_name>
</conf_room>
<conf_room>
<conf_id>8205</conf_id>
<conf_name>Conf 6</conf_name>
</conf_room>
<conf_room>
<conf_id>8206</conf_id>
<conf_name>Conf 7</conf_name>
</conf_room>
<conf_room>
<conf_id>8207</conf_id>
<conf_name>sdfsdf</conf_name>
</conf_room>
<conf_room>
<conf_id>8208</conf_id>
<conf_name>Conf 9</conf_name>
</conf_room>
<conf_room>
<conf_id>8209</conf_id>
<conf_name>Conf 10</conf_name>
</conf_room>
</conf_rooms>In my code I need to get the value of the <conf_name> element.
Here is my code that successfully returns the <conf_id> element:
                    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
                    factory.setIgnoringComments(true);
                    factory.setCoalescing(true);
                    factory.setNamespaceAware(false);
                    factory.setValidating(false);
                    DocumentBuilder builder = factory.newDocumentBuilder();
                    document = builder.parse(file);
                    NodeList confrooms = document.getElementsByTagName("conf_room");
                    int is = confrooms.getLength();
                    for(int i=0;i<is;i++)
                        Element confroom = (Element) confrooms.item(i);
                        Node title = confroom.getFirstChild();
                        while(title != null && title.getNodeType() != Node.ELEMENT_NODE)
                            title = title.getNextSibling();
                        if(title != null)
                                System.out.println(title.getFirstChild().getNodeValue());
                    }Now since my xml doc only has a <conf_id> and a <conf_name> I thought that if I replaced the following :
Node title = confroom.getFirstChild();
with
Node title = confroom.getLastChild();
it would return the value of <conf_name>
Doesnt work, doesnt return any value.
Any ideas or help would be greatly appreciated!!!
TIA!

Answer 1

Dr.Clap is right. You have to watch out for that. Here is what one of your conf_room nodes looks like:
    NODE:
      NAME: conf_room
      TYPE: element
      VALUE: null
      CHILDREN:
        NODE:
          NAME: #text
          TYPE: text
          VALUE:
        NODE:
          NAME: conf_id
          TYPE: element
          VALUE: null
          CHILDREN:
            NODE:
              NAME: #text
              TYPE: text
              VALUE: 8209
        NODE:
          NAME: #text
          TYPE: text
          VALUE:
        NODE:
          NAME: conf_name
          TYPE: element
          VALUE: null
          CHILDREN:
            NODE:
              NAME: #text
              TYPE: text
              VALUE: Conf 10
        NODE:
          NAME: #text
          TYPE: text
          VALUE:As you can see, the whitespace is in there as text nodes. When you replace getFirstChild with getLast child you get a reference to that last empty text node. Then, your while loop executed and tried to move to the next sibling, which is null.
You could change your for loop to something like:
        for(int i=0;i<is;i++)
            Element confroom = (Element) confrooms.item(i);
            System.out.println("CONF ID: " + confroom.getElementsByTagName("conf_id").item(0).getTextContent());
            System.out.println("CONF NAME: " + confroom.getElementsByTagName("conf_name").item(0).getTextContent());
        }The other option would be to create a simple Schema for your XML. That way you can set factory.setIgnoringElementContentWhitespace() which will eliminate all those extra whitespace nodes (and insure your XML is valid).
-Paco