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09

Parsing XML String using DOM

Posted by Albin Joseph | Posted in Java | Posted on 09-10-2007

Tagged Under : , ,

The first step in parsing an XML String using DOM is to get the org.w3c.dom.Document object from our String object. Here I am going to parse the following XML which is stored in a String variable xmlString

?View Code XML
<data>
   <address>
          <name>Tom</name>
          <city>Bangalore</city>
    </address>
   <address>
        <name>Chris</name>
        <city>New Jersey</city>
   </address>
</data>

First lets create a Document object using xmlString object.

?View Code JAVA
    javax.xml.parsers.DocumentBuilderFactory factory = javax.xml.parsers.DocumentBuilderFactory.newInstance();
    javax.xml.parsers.DocumentBuilder db = factory.newDocumentBuilder();
    org.xml.sax.InputSource inStream = new org.xml.sax.InputSource();
 
    inStream.setCharacterStream(new java.io.StringReader(xmlString));
    org.xml.sax.Document doc = db.parse(inStream);

Once we got the Document object we need to get the NodeList from our Document object.

?View Code JAVA
org.w3c.dom.NodeList nodeList = doc.getElementsByTagName("address");

This would return all the address elements available in our XML. Next we need to loop through all the nodes in our NodeList and get the nodes present.

?View Code JAVA
for(int index=0; index < nodeList.getLength(); index++) {
      org.w3c.dom.Node node = nodeList.item(index);
}

Once we got the Node we need to cast it to an org.w3c.dom.Element object if the Node is of type org.w3c.dom.Element

?View Code JAVA
if (node.getNodeType() == org.w3c.dom.Node.ELEMENT_NODE) {
      org.w3c.dom.Element element = (org.w3c.dom.Element) node;
}

Now we need to find out all the names that is coming under the current address.

?View Code JAVA
 
org.w3c.dom.NodeList nameNode = element.getElementsByTagName("name");

Now we need to do all the above exercise again to get the final element from where we can get the value.

?View Code JAVA
for(int iIndex=0; iIndex< nameNode.getLength(); iIndex++) {
    if (nameNode.item(iIndex).getNodeType() == org.w3c.dom.Node.ELEMENT_NODE) {
         org.w3c.dom.Element nameElement = (org.w3c.dom.Element) nameNode.item(iIndex);
         System.out.println("Name = " +nameElement.getFirstChild().getNodeValue().trim());
     }
}

So the complete code is

?View Code JAVA
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder db = factory.newDocumentBuilder();
InputSource inStream = new InputSource();
inStream.setCharacterStream(new StringReader(xmlString));
Document doc = db.parse(inStream);	
 
NodeList nodeList = doc.getElementsByTagName("address");
 
for(int index=0; index < nodeList.getLength(); index++)
{
        Node node = nodeList.item(index);
 
	if (node.getNodeType() == Node.ELEMENT_NODE)
	{
	        Element element = (Element) node;
 
		NodeList nameNode = element.getElementsByTagName("name");
 
		for(int iIndex=0; iIndex< nameNode.getLength(); iIndex++)
		{
		        if (nameNode.item(iIndex).getNodeType() ==Node.ELEMENT_NODE)
			{
				Element nameElement = (Element) nameNode.item(iIndex);
				System.out.println("Name = " +nameElement.getFirstChild().getNodeValue().trim());
			}
	        }
        }
}

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