Java saying XML Document Not Well Formed

Question

Java's XML parser seems to be thinking that my XML document is not well formed following the root element. But I've validated it with several tools and they all disagree. It's probably an error in my code rather than in the document itself. I'd really appreciate any help you all could offer me.

Here is my Java method:

private void loadFromXMLFile(File f) throws ParserConfigurationException, IOException, SAXException {
    File file = f;
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    DocumentBuilder db;
    Document doc = null;
    db = dbf.newDocumentBuilder();
    doc = db.parse(file);
    doc.getDocumentElement().normalize();
    String desc = "";
    String due = "";
    String comment = "";
    NodeList tasksList = doc.getElementsByTagName("task");
    for (int i = 0; i  tasksList.getLength(); i++) {
        NodeList attributes = tasksList.item(i).getChildNodes();
        for (int j = 0; i < attributes.getLength(); j++) {
        Node attribute = attributes.item(i);
        if (attribute.getNodeName() == "description") {
            desc = attribute.getTextContent();
        }
        if (attribute.getNodeName() == "due") {
            due = attribute.getTextContent();
        }
        if (attribute.getNodeName() == "comment") {
            comment = attribute.getTextContent();
        }
        tasks.add(new Task(desc, due, comment));
        }
        desc = "";
        due = "";
        comment = "";
    }
}

The following is the XML file I'm trying to load:

<?xml version="1.0"?>  
<tasklist>  
    <task>  
        <description>Task 1</description>  
        <due>Due date 1</due>  
        <comment>Comment 1</comment>  
        <completed>false</completed>  
    </task>  
    <task>  
        <description>Task 2</description>  
        <due>Due date 2</due>  
        <comment>Comment 2</comment>  
        <completed>false</completed>  
    </task>  
    <task>  
        <description>Task 3</description>  
        <due>Due date 3</due>  
        <comment>Comment 3</comment>  
        <completed>true</completed>  
    </task>  
</tasklist>

And here is the error message java is throwing for me:

run:
[Fatal Error] tasks.xml:28:3: The markup in the document following the root element must be well-formed.
May 17, 2010 6:07:02 PM todolist.TodoListGUI <init>
SEVERE: null
org.xml.sax.SAXParseException: The markup in the document following the root element must be well-formed.
        at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:239)
        at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:283)
        at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:208)
        at todolist.TodoListGUI.loadFromXMLFile(TodoListGUI.java:199)
        at todolist.TodoListGUI.<init>(TodoListGUI.java:42)
        at todolist.Main.main(Main.java:25)
BUILD SUCCESSFUL (total time: 19 seconds)

For reference TodoListGUI.java:199 is

doc = db.parse(file);

If context is helpful to anyone here, I'm trying to write a simple GUI application to manage a todo list that can read and write to and from XML files defining the tasks.

Answer 1

org.xml.sax.SAXParseException: The markup in the document following the root element must be well-formed.

This particular exception indicates that there is more than one root element in the XML document. In other words, the <tasklist> is not the only root element. To take your XML document as an example, think of one without the <tasklist> element and with three <task> elements in the root. This would cause this kind of exception.

Since the XML file you posted looks fine, the problem lies somewhere else. It look like that it is not parsing the XML file you expect that it is parsing. For quick debugging, add the following to top of your method:

System.out.println(f.getAbsolutePath());

Locate the file in the disk file system and verify it.

Answer 2

I think there may be something wrong with the actual file. When I copy your code but use the XML as a string input to the parser it works fine (after fixing a couple of issues - attributes.item(i) should be attributes.item(j) and you need to break out of the loop when attribute == null).

In trying to reproduce your error, I can get the same message if I add another <tasklist></tasklist> element. This is because the XML no longer has a single root element (tasklist). Is this the problem you are seeing? Does the XML in tasks.xml have a single root element?