Develop Reference

How to fetch a value from XML using XPATH

This is my xml and i wanted to fetch value of Id tag '4654'
<Entity>
<acc>
<id>4654</id>
<name>abc</name>
</acc>
<acc>
<id>5465</id>
<name>xyz</name>
</acc>
I am using this code to retrieve the Id value
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document document = builder.parse(new InputSource(new StringReader(xml)));
XPath xPath = XPathFactory.newInstance().newXPath();
NodeList node = (NodeList) xPath.evaluate("/Entity/acc/id/text()", document, XPathConstants.NODE);
System.out.println("node length:"+node.getLength());
System.out.println("node value:"+ node.item(0).getNodeValue());
return node.item(0).getNodeValue();
Output returns null
Any help would be appreciated

You need to use XPathConstants.NODESET instead of XPathConstants.NODE
or you can keep it as XPathConstants.NODE and change the evaluate to return Node
Node node = (Node) xPath.evaluate("/Entity/acc/id/text()", document, XPathConstants.NODE);

Retrieve node element's value based on attribute

How to retrieve node element's value based on attribute name using dom & xml parsing
<ROOT>
<A>
<aa name="xyz">k,l,m </aa>
<aa name="pqr">a,b,h </aa>
<aa name="abc">s,t,r </aa>
...
</A>
<B>
<bb name="t1">r,st,t</bb>
...
</B>
</ROOT>
...
Fragment of implementation tried:
NodeList nodeList = <xmlDoc>.getElementsByTagName("aa");
for (int i = 0; i < nodeList.getLength(); i++)
{
Node node = nodeList.item(i);
if (node.getNodeType() == Node.ELEMENT_NODE)
{
Element element = (Element) node;
System.out.println(element.getTextContent());
// ? getNodeValue() // ? how to get by passing attribute name as matching criteria,
// f.e : how to get a,b,h printed for node aa with attribute name as pqr

For attribute it will be : element.getAttribute("name");
If you want to search by attribute, then
XPath xpath = XPathFactory.newInstance().newXPath();
NodeList nl = (NodeList)xpath.compile("//aa[#name='pqr']").evaluate(doc, XPathConstants.NODESET);
//Rest of the code same
*Please change the xpath according to your need. I did not run it myself, but you get the idea.

Java XML with namespace issue

I have this code:
org.w3c.dom.Document doc = docBuilder.parse(representation.getStream());
Element element = doc.getDocumentElement();
NodeList nodeList = element.getElementsByTagName("xnat:MRSession.scan.file");
for (int i = 0; i < nodeList.getLength(); i++) {
Node node = nodeList.item(i);
if (node.getNodeType() == Node.ELEMENT_NODE) {
// do something with the current element
my problem is with getElementsByTagName("xnat:MRSession.scan.file")
my xml looks like this:
<?xml version="1.0" encoding="UTF-8"?><xnat:MRSession "REMOVED DATA IGNORE">
<xnat:sharing>
<xnat:share label="23_MR1" project="BOGUS_GSU">
<!--hidden_fields[xnat_experimentData_share_id="1",sharing_share_xnat_experimentDa_id="xnat_E00001"]-->
</xnat:share>
</xnat:sharing>
<xnat:fields>
<xnat:field name="studyComments">
<!--hidden_fields[xnat_experimentData_field_id="1",fields_field_xnat_experimentDat_id="xnat_E00001"]-->S</xnat:field>
</xnat:fields>
<xnat:subject_ID>xnat_S00002</xnat:subject_ID>
<xnat:scanner manufacturer="GE MEDICAL SYSTEMS" model="GENESIS_SIGNA"/>
<xnat:prearchivePath>/home/ryan/xnat_data/prearchive/BOGUS_OUA/20120717_131900137/23_MR1</xnat:prearchivePath>
<xnat:scans>
<xnat:scan ID="1" UID="1.2.840.113654.2.45.2.108830" type="SAG LOCALIZER" xsi:type="xnat:mrScanData">
<!--hidden_fields[xnat_imageScanData_id="1"]-->
<xnat:image_session_ID>xnat_E00001</xnat:image_session_ID>
<xnat:quality>usable</xnat:quality>
<xnat:series_description>SAG LOCALIZER</xnat:series_description>
<xnat:scanner manufacturer="GE MEDICAL SYSTEMS" model="GENESIS_SIGNA"/>
<xnat:frames>29</xnat:frames>
<xnat:file URI="/home/ryan/xnat_data/archive/BOGUS_OUA/arc001/23_MR1/SCANS/1/DICOM/scan_1_catalog.xml" content="RAW" file_count="29" file_size="3968052" format="DICOM" label="DICOM" xsi:type="xnat:resourceCatalog">
So Basically I need to be able to iterate through all the xnat:MRSession/xnat:scan/xnat:file
elements and make some changes. Problem is
getElementsByTagName("xnat:MRSession.scan.file")
Is always null. Please help. Thanks

You could try the following using XPath:
Document document = // the parsed document
XPathFactory xPathFactory = XPathFactory.newInstance();
NodeList allFileNodes = xPathFactory.newXPath().evaluate("\\XNAT_NAMESPACE:file", document.getDocumentElement(), XPathConstants.NODESET);
Instead XNAT_NAMESPACE you would need to specify the exact namespace that is meant with the prefix "xnat" in your example.

Child elements of DOM

I have this XML file:
<scene>
<texture file="file1.dds"/>
<texture file="file2.dds"/>
...
<node name="cube">
<texture name="stone" unit="0" sampler="anisotropic"/>
</node>
</scene>
I need all child element of 'scene' that are named "texture", but with this code:
Element rootNode = document.getDocumentElement();
NodeList childNodes = rootNode.getElementsByTagName("texture");
for (int nodeIx = 0; nodeIx < childNodes.getLength(); nodeIx++) {
Node node = childNodes.item(nodeIx);
if (node.getNodeType() == Node.ELEMENT_NODE) {
// cool stuff here
}
}
i also get the 'texture' elements which are inside 'node'.
How can i filter these out? Or how can i get only the elements that are direct childs of 'scene'?

You can do it using Xpath, consider the following example taken from the JAXP Specification 1.4 (which I recommend you to consult for this):
// parse the XML as a W3C Document
DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
org.w3c.Document document = builder.parse(new File("/widgets.xml"));
// evaluate the XPath expression against the Document
XPath xpath = XPathFactory.newInstance().newXPath();
String expression = "/widgets/widget[#name='a']/#quantity";
Double quantity = (Double) xpath.evaluate(expression, document, XPathConstants.NUMBER);

I found myself a solution that works fine:
Element parent = ... ;
String childName = "texture";
NodeList childs = parent.getChildNodes();
for (int nodeIx = 0; nodeIx < childs.getLength(); nodeIx++) {
Node node = childs.item(nodeIx);
if (node.getNodeType() == Node.ELEMENT_NODE
&& node.getNodeName().equals(name)) {
// cool stuff here
}
}

DOM Parser query in JAVA

<subjectOf typeCode="SUBJ">
<annotation classCode="ACT" moodCode="EVN">
<realmCode code="QD" />
<code code="SPECIALNOTE"></code>
<text><![CDATA[<strong>** New York State approval pending. This test is not available for New York State patient testing **</br> ]]></text>
</annotation>
</subjectOf>
<subjectOf typeCode="SUBJ">
<annotation classCode="ACT" moodCode="EVN">
<realmCode code="QD" />
<code code="PREFERREDSPECIMEN"></code>
<text><![CDATA[2 mL Second void urine <strong>or </strong>2-hour urine <strong>or </strong> 2 mL Urine with no preservative]]></text>
</annotation>
</subjectOf>
In DOM parsing, how can I traverse through the above XML and get the <text> tag value depending upon a <code> tag attribute having a given value. For example, I want to get the following text:
<strong>** New York State approval pending. This test is not available
for New York State patient testing **</br>
...based on the <code> tag with a code attribute where value="SPECIALNOTE".
public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException, XPathExpressionException {
DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
domFactory.setNamespaceAware(true);
DocumentBuilder builder = domFactory.newDocumentBuilder();
Document doc = builder.parse("xml.xml");
XPath xpath = XPathFactory.newInstance().newXPath(); // XPath Query for showing all nodes value
XPathExpression expr = xpath.compile("/testCodeIdentifier/subjectOf/subjectOf/annotation/code[#code='SPECIALNOTE']");
Object result = expr.evaluate(doc, XPathConstants.NODESET);
NodeList nodes = (NodeList) result;
for (int i = 0; i < nodes.getLength(); i++) {
System.out.println("........"+nodes.item(i).getNodeValue()+"........");
}
}
}
Appreciate the help in advance...

First, your XPath expression has an error; subjectOf is repeated unnecessarily:
/subjectOf/subjectOf
Now, assuming you really do need a reference to the code node that precedes the target text element, then use the following:
XPathExpression expr = xpath.compile(
"/testCodeIdentifier/subjectOf/annotation/code[#code='SPECIALNOTE']");
Node node = (Node) expr.evaluate(doc, XPathConstants.NODE);
System.out.println(getNextElementSibling(node).getTextContent());
Where getNextElementSibling is defined as follows:
public static Node getNextElementSibling(Node node) {
Node next = node;
do {
next = next.getNextSibling();
} while ((next != null) && (next.getNodeType() != Node.ELEMENT_NODE));
return next;
}
A couple of notes about this:
The reason that getNextSibling did not originally work for you is (most likely) because the next sibling of the referenced code element is a text node, not an element node. (The whitespace between code and text is significant.) That's why we need getNextElementSibling.
We're selecting a single node, so we're using XPathConstants.NODE instead if XPathConstants.NODELIST
Note that you should probably just do as #Lukas suggests and modify your XPath expression to directly select the target text.
Here's how to get the text directly (as a String):
XPathExpression expr = xpath.compile(
"/testCodeIdentifier/subjectOf/annotation[code/#code='SPECIALNOTE']/text/text()");
String text = (String) expr.evaluate(doc, XPathConstants.STRING);
System.out.println(text);
Here's how to first get a reference to the element and then retrieve the contents of its CDATA section:
XPathExpression expr = xpath.compile(
"/testCodeIdentifier/subjectOf/annotation[code/#code='SPECIALNOTE']/text");
Node text = (Node) expr.evaluate(doc, XPathConstants.NODE);
System.out.println(text.getTextContent());

Fix your XPath expression like this:
/testCodeIdentifier/subjectOf/annotation[code/#code='SPECIALNOTE']/text
You could then, for instance, access the CDATA content using
Node.getTextContent();
UPDATE: The above XPath seemed correct at the time I posted it. In the meantime, you have completely changed your XML code and now, the XPath would read
/testCodeIdentifier/subjectOf/code/subjectOf/annotation[code/#code='SPECIALNOTE']/text
Or, because I am guessing that this question is so messy, it's still wrong, just do:
//annotation[code/#code='SPECIALNOTE']/text

Finally i have got the answer for my question by myself.... Below code is being working for my XML to be parsed...
XPath xpath = XPathFactory.newInstance().newXPath();
// XPath Query for showing all nodes value
XPathExpression expr = xpath.compile("//testCodeIdentifier/subjectOf/order/subjectOf/annotation/code[#code='SPECIALNOTE']/following-sibling::text/text()");
Object result = expr.evaluate(doc, XPathConstants.NODESET);
NodeList nodes = (NodeList) result;
for (int i = 0; i < nodes.getLength(); i++) {
System.out.println(nodes.item(i).getNodeValue());
}
Thank you people who have ansewered in this post but this is a possible solution for it. Have a mark on it.