DOM

Question 1

What is DOM and why is it used?

Answer 1

DOM is the Document Object Model. This can be used with a Java API.

It reads the xml file in can be used to create or amend xml documents.

The API provides:

• Interfaces and objects to represent and manipulate a document
• Semantics of them.
• Relationships amongst interfaces and objects

Question 2

What are the important methods for amending an XML document?

• Not including the methods for creating a new document.*
• Clue: there are 8!*

Answer 2

1. .getDocumentElement - return a list of child objects of any node.
2. .getChildNodes - return a list of child objects of any node
3. .parse - reads the file in (xml errors picked up) and returns a datatype
4. .getElementsByTagName(String tagname) - returns NodeList representing the result of an in-order traversal of the doc in which Nodes with elements of tag name
5. .createXXXX - create new Nodes e.g. createTextNode
6. .item(i) - get Node in list of position i
7. .replaceChild(newNode, oldNode) - replaces the oldNode with newNode.
8. .getNodeValue() - return value of the node

Question 3

What are the important methods for creating an XML document?

Answer 3

1. .newDocument() - replaces parse
2. .createElement(“name”) - create element before append
3. .appendChild(new) - append child to new document or Node

Question 4

How do you copy part of an XML document to another one?

Answer 4

By using import

Question 5

What risks/differences are there between using DOM and creating your own code to manipulate XML in Java?

Answer 5

Your own code may be missing something and you can’t confirm it is generating well formed XML correctly. Whereas we know DOM will always generate and parse XML correctly.