Develop Reference

Getting all attributes of an xml by using java and Xpath

I have the following xml:
<?xml version="1.0" encoding="UTF-8"?>
<root xmlns="http://www.test.com/rest/v1" xmlns:xs="http://www.w3.org/2001/XMLSchema">
<child test="folder" id="2019-05-15-04.52.05.641880A01" />
<child test="folder" id="2019-05-15-04.52.05.901880A02" />
</root>
I want to read the above xml by using Java code and Xpath, retrieve the id's of the child nodes(i.e. id="2019-05-15-04.52.05.641880A01" and id="2019-05-15-04.52.05.901880A02") and store them into List. I tried with the following java code:
InputSource source = new InputSource(new StringReader(xml));
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
org.w3c.dom.Document document = db.parse(source);
XPathFactory xpathFactory = XPathFactory.newInstance();
XPath xpath = xpathFactory.newXPath();
return xpath.evaluate(expression, document);
I called the above the above method with the following Xpath along with the input xml:
*[local-name()='root']/*[local-name()='child']/#id
But I am getting only one id, not all the id's. Any idea on how to get all the id's?

I think your Xpath is right. You can verify it with the following test class.
package com.idsk.commons.xsl;
import java.io.IOException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
public class Test {
public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException, XPathExpressionException {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setNamespaceAware(true); // never forget this!
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse("D://NewFile.xml");
// Create XPath
XPathFactory xpathfactory = XPathFactory.newInstance();
XPath xpath = xpathfactory.newXPath();
XPathExpression expr = xpath.compile("*[local-name()='root']/*[local-name()='child']/#id");
Object result = expr.evaluate(doc, XPathConstants.NODESET);
NodeList nodes = (NodeList) result;
List<String> ids = new ArrayList<>();
for (int i = 0; i < nodes.getLength(); i++) {
System.out.println(nodes.item(i).getNodeValue());
ids.add(nodes.item(i).getNodeValue()); //store them into List
}
}
}
It will create following output:
2019-05-15-04.52.05.641880A01
2019-05-15-04.52.05.901880A02

get the number of elements in an XML document

I need to get the total number of nodes in an xml file in java ( java dom ...)
In the file below, the total number of elements is 15
<?xml version="1.0" encoding="UTF-8"?>
<personnes>
<etudiant classe="P2">
<nom>CynO</nom>
<prenoms>
<prenom>Nicolas</prenom>
<prenom>Laurent</prenom>
</prenoms>
<age>25</age>
</etudiant>
<etudiant classe="P1">
<nom>Superwoman</nom>
<prenoms>
<prenom>Sia</prenom>
</prenoms>
<age>34</age>
</etudiant>
<etudiant classe="P3">
<nom>Don Corleone</nom>
<age>28</age>
</etudiant>
</personnes>
thank you

Try with following code snippet. It is worked for me.
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
public class CountNoOfElements{
public static void main(String args[]) throws Exception {
String filepath = "test.xml";
DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = docFactory.newDocumentBuilder();
Document doc = docBuilder.parse(filepath);
NodeList nodeList = doc.getElementsByTagName("*");
int count = nodeList.getLength();
System.out.println("Total of elements : " + count);
}
}

How I need to get tag name of sub child in xml by comparing the attribute value and given string value using Java?

I have a xml file. I need to get the sub child tag of the parent tag (Body) in xml file using Java. First I need to use DOM for reading an element
and get xml file from my local machine drive. I have one String varaible (Sring getSubChildValue = "181_paragraph_13") and I need to compare the value
with each and every attribute Value in the Xml file. If the given Value may be in sub child tag,I cont able to get a Value.
what I need to do for compare the String variable and with Xml File
What I need to do for print the Tag name if the String value is equal to any attrinbute Value.
Example: (P) Tag is the sub child of Tag (Body) which contain the given String Value. So I need to get tag name P.
How to avoid the Hard coding the sub-child Name to get the solution?
Example XML file:
<parent>
<Body class="student" id="181_student_method_3">
<Book class="Book_In_School_11" id="181_student_method_11"/>
<subject class="subject_information " id="181_student_subject_12"/>
<div class="div_passage " id="181_div_method_3">
<p class=" paragraph_book_name" id="181_paragraph_13">
<LiberaryBook class="Liberary" id="181_Liberary_9" >
<Liberary class="choice "
id="Liberary_replace_1" Uninversity="University_Liberary_1">
Dubliners</Liberary>
<Liberary class="choice "
id="Liberary_replace_2" Uninversity="University_Liberary_2">
Adventure if sherlock Holmes</Liberary>
<Liberary class="choice "
id="Liberary_replace_3" Uninversity="University_Liberary_3">
Charlotte’s Web</Liberary>
<Liberary class="choice "
id="Liberary_replace_4" Uninversity="University_Liberary_4">
The Outsiders</Liberary>
</LiberaryBook>
</p>
</div>
</Body>
</parent>
Example Java code:
import java.io.File;
import java.io.IOException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
public class PerfectTagChange {
public static void main(String[] args) {
String filePath = "/xmlfile/Xml/check/sample.xml";
File xmlFile = new File(filePath);
DocumentBuilderFactory
dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder;
try {
dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(xmlFile);
doc.getDocumentElement().normalize();
Element root = doc.getDocumentElement();
changeValue(root,doc);
doc.getDocumentElement().normalize();
TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(new File("/xmlfile/Xml/check/Demo.xml"));
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.transform(source, result);
System.out.println("XML file updated successfully");
} catch (SAXException | ParserConfigurationException | IOException | TransformerException e1) {
e1.printStackTrace();
}
}
//This Method is used to check which attribute contain given string Value : Hard code parent tag, But no other tag.
private static void changeValue(Node someNode,Document doc) {
Sring getSubChildValue = "181_paragraph_13"
NodeList childs = someNode.getChildNodes();
for (int in = 0; in < childs.getLength();) {
Node child = childs.item(in);
if (child.getNodeType() == Document.ELEMENT_NODE) {
if (child.getNodeName().equalsIgnoreCase("Body") ) {
//If I hard code the ID here on getNamedItem("id"),
If the attribute Name got Changed from ID to Name
it will be in problem.
//3.What is the solution for solving the problem.
if(child.getAtrribute.getNamedItem("id").getNodeValue().equals(getSubChildValue)){
system.out.println(child.getAtrribute.getNamedItem("id").getNodeValue());
}
}
}
}
}

If you change your code to this:
private static void changeValue(Node someNode, Document doc, String searchString) throws Exception {
XPath xPath = XPathFactory.newInstance().newXPath();
NodeList nodes = (NodeList) xPath.evaluate("//*[#*=\"" + searchString + "\"]",
doc.getDocumentElement(),
XPathConstants.NODESET);
for (int i = 0; i < nodes.getLength(); i++) {
System.out.println("Tagname: " + nodes.item(i).getNodeName());
}
}
you don't have the name of the attribute to be hardcoded.
EDIT:
Added searchString as parameter.

Parse XML in Java with data next to attribute

I need to get the value of certain XML objects in Java, but they are in the attribute tag. I'm not sure how to go about this.
XML Example:
<node id="359832" version="5" timestamp="2008-05-20T15:20:46Z" uid="4499" changeset="486842" lat="50.9051565" lon="6.963755">
<tag k="amenity" v="restaurant"/>
<tag k="name" v="Campus"/>
</node>
<node id="451153" version="4" timestamp="2009-09-17T18:09:14Z" uid="508" changeset="2514480" lat="51.6020306" lon="-0.1935029">
<tag k="amenity" v="restaurant"/>
<tag k="created_by" v="JOSM"/>
<tag k="name" v="Sun and Sea"/>
</node>
I need to get the value of lat and lon, which are inside of the <node> in addition to the value of <tag k="name" v="Sun and Sea"/>, and with each set of this, do something with it.
Pseudocode:
foreach(node in xmlFile)
{
String name = this.name;
double lat = this.lat;
double lon = this.lon;
//my own thing here
}
I have looked, but am unable to find anything on how to get the values for lat and lon, since they are next to the attribute instead of nested. I don't need to use an input-stream, the xml file is small enough that I cant store it in memory.

package com.sandbox;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import java.io.IOException;
public class Sandbox {
public static void main(String argv[]) throws IOException, SAXException, ParserConfigurationException {
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
Document document = documentBuilder.parse(Sandbox.class.getResourceAsStream("/foo.xml"));
NodeList nodeNodeList = document.getElementsByTagName("node");
for (int i = 0; i < nodeNodeList.getLength(); i++) {
Node nNode = nodeNodeList.item(i);
System.out.println(nNode.getAttributes().getNamedItem("lat").getNodeValue());
System.out.println(nNode.getAttributes().getNamedItem("lon").getNodeValue());
}
}
}
This printed out:
50.9051565
6.963755
51.6020306
-0.1935029

How to use XPath on xml docs having default namespace

I want to manipulate xml doc having default namespace but no prefix. Is there a way to use xpath without namespace uri just as if there is no namespace?
I believe it should be possible if we set namespaceAware property of documentBuilderFactory to false. But in my case it is not working.
Is my understanding is incorrect or I am doing some mistake in code?
Here is my code:
DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
domFactory.setNamespaceAware(false);
try {
DocumentBuilder builder = domFactory.newDocumentBuilder();
Document dDoc = builder.parse("E:/test.xml");
XPath xPath = XPathFactory.newInstance().newXPath();
NodeList nl = (NodeList) xPath.evaluate("//author", dDoc, XPathConstants.NODESET);
System.out.println(nl.getLength());
} catch (Exception e) {
e.printStackTrace();
}
Here is my xml:
<?xml version="1.0" encoding="UTF-8"?>
<root xmlns="http://www.mydomain.com/schema">
<author>
<book title="t1"/>
<book title="t2"/>
</author>
</root>

The XPath processing for a document that uses the default namespace (no prefix) is the same as the XPath processing for a document that uses prefixes:
For namespace qualified documents you can use a NamespaceContext when you execute the XPath. You will need to prefix the fragments in the XPath to match the NamespaceContext. The prefixes you use do not need to match the prefixes used in the document.
http://download.oracle.com/javase/6/docs/api/javax/xml/namespace/NamespaceContext.html
Here is how it looks with your code:
import java.util.Iterator;
import javax.xml.namespace.NamespaceContext;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
public class Demo {
public static void main(String[] args) {
DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
domFactory.setNamespaceAware(true);
try {
DocumentBuilder builder = domFactory.newDocumentBuilder();
Document dDoc = builder.parse("E:/test.xml");
XPath xPath = XPathFactory.newInstance().newXPath();
xPath.setNamespaceContext(new MyNamespaceContext());
NodeList nl = (NodeList) xPath.evaluate("/ns:root/ns:author", dDoc, XPathConstants.NODESET);
System.out.println(nl.getLength());
} catch (Exception e) {
e.printStackTrace();
}
}
private static class MyNamespaceContext implements NamespaceContext {
public String getNamespaceURI(String prefix) {
if("ns".equals(prefix)) {
return "http://www.mydomain.com/schema";
}
return null;
}
public String getPrefix(String namespaceURI) {
return null;
}
public Iterator getPrefixes(String namespaceURI) {
return null;
}
}
}
Note:
I also used the corrected XPath suggested by Dennis.
The following also appears to work, and is closer to your original question:
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
public class Demo {
public static void main(String[] args) {
DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
try {
DocumentBuilder builder = domFactory.newDocumentBuilder();
Document dDoc = builder.parse("E:/test.xml");
XPath xPath = XPathFactory.newInstance().newXPath();
NodeList nl = (NodeList) xPath.evaluate("/root/author", dDoc, XPathConstants.NODESET);
System.out.println(nl.getLength());
} catch (Exception e) {
e.printStackTrace();
}
}
}

Blaise Doughan is right, attached code is correct.
Problem was somewhere elese. I was running all my tests through Application launcher in Eclipse IDE and nothing was working. Then I discovered Eclipse project was cause of all grief. I ran my class from command prompt, it worked. Created a new eclipse project and pasted same code there, it worked there too.
Thank you all guys for your time and efforts.

I've written a simple NamespaceContext implementation (here), that might be of help. It takes a Map<String, String> as input, where the key is a prefix, and the value is a namespace.
It follows the NamespaceContext spesification, and you can see how it works in the unit tests.
Map<String, String> mappings = new HashMap<>();
mappings.put("foo", "http://foo");
mappings.put("foo2", "http://foo");
mappings.put("bar", "http://bar");
context = new SimpleNamespaceContext(mappings);
context.getNamespaceURI("foo"); // "http://foo"
context.getPrefix("http://foo"); // "foo" or "foo2"
context.getPrefixes("http://foo"); // ["foo", "foo2"]
Note that it has a dependency on Google Guava