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how to get specific tag content inside parant tag from id in xml using java?

I have an XML file as below. I want to get its specific child tag from the parent tag using java.
<?xml version="1.0"?>
<class>
<question id="scores">
<ans>12</ans>
<ans>32</ans>
<ans>44</ans>
</question>
<question id="ratings">
<ans>10</ans>
<ans>22</ans>
<ans>45</ans>
<ans>100</ans>
</question>
<default>
Sorry wrong
</default>
</class>
i want the function to be like this
String function(String id)
it will return the ans tag randomly
i.e if I give input id=scores, the program will look in the XML tag for scores as id and get length()of its children, in this case, 3, then retun randomly like 32 or 44 or 12.if id is not present, return default.
my code so far
public class ChatBot {
private String filepath="E:\\myfile.xml";
private File file;
private Document doc;
public ChatBot() throws SAXException, IOException, ParserConfigurationException {
file = new File("E:\\myfile.xml");
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
doc = db.parse(file);
}
String Function(String id){
// This part
return null;
}
}

As suggested by #LMC (because of org.w3c.dom.Document.getElementById() not recognizing arbitrary id attributes as IDs for getElementById() or as a browser would, mostly for HTML semantics/format), maybe:
String Function(String id) throws XPathExpressionException {
XPath xPath = XPathFactory.newInstance().newXPath();
// Be aware: id inserted without any escaping!
NodeList parents = (NodeList)xPath.evaluate("/class/question[#id='" + id + "']", doc, XPathConstants.NODESET);
if (parents.getLength() < 1) {
return null;
} else if (parents.getLength() > 1) {
// Huh, duplicates?
}
Element parent = (Element)parents.item(0);
NodeList children = parent.getChildNodes();
List<Element> answers = new ArrayList<Element>();
for (int i = 0, max = children.getLength(); i < max; i++) {
if (children.item(i).getNodeType() != Node.ELEMENT_NODE) {
continue;
}
if (children.item(i).getNodeName().equals("ans") != true) {
// Huh?
continue;
}
answers.add((Element)children.item(i));
}
if (answers.size() <= 0) {
return null;
}
int selection = (int)(Math.random() * answers.size());
return answers.get(selection).getTextContent();
}

How to use Java XPath with KML files and namespaces on Android

I'm struggling with how to use XPath on KML files that contain the new gx:Track and gx:coord tags. The problem is with how to use XPath with namespaces under Android.
I've looked at a number of examples, including these
https://www.ibm.com/developerworks/library/x-nmspccontext/index.html
https://howtodoinjava.com/xml/xpath-namespace-resolution-example/
XPath with namespace in Java
NamespaceContext and using namespaces with XPath
but I can't seem to get even those examples to work.
The following code and output illustrates my problem:
public App() {
super();
try {
test( testDoc1() );
test( testDoc2() );
} catch( Exception e ) {
e.printStackTrace();
} finally {
Log.d( "TEST-FINISHED", "test is finished" );
}
}
private String toXmlString( Document document ) throws TransformerException {
DOMSource domSource = new DOMSource( document );
StringWriter writer = new StringWriter();
StreamResult result = new StreamResult( writer );
TransformerFactory tf = TransformerFactory.newInstance();
Transformer transformer = tf.newTransformer();
transformer.transform( domSource, result );
return writer.toString();
}
private Document testDoc1() throws ParserConfigurationException {
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
documentBuilderFactory.setNamespaceAware( true );
Document mDocument = documentBuilderFactory.newDocumentBuilder().newDocument();
String XMLNS_NAMESPACE_URI = "http://www.w3.org/2000/xmlns/";
Element mKmlElement = mDocument.createElement( "kml" );
mKmlElement.setAttributeNS( XMLNS_NAMESPACE_URI, "xmlns", "http://www.opengis.net/kml/2.2" );
mKmlElement.setAttributeNS( XMLNS_NAMESPACE_URI, "xmlns:gx", "http://www.google.com/kml/ext/2.2" );
mDocument.appendChild( mKmlElement );
Element mPlacemarkElement = mDocument.createElement( "Placemark" );
mKmlElement.appendChild( mPlacemarkElement );
Element gxTrackElement = mDocument.createElement( "gx:Track" );
mPlacemarkElement.appendChild( gxTrackElement );
Element gxCoordElement = mDocument.createElement( "gx:coord" );
gxCoordElement.setTextContent( "-122.207881 37.371915 156.000000" );
gxTrackElement.appendChild( gxCoordElement );
return mDocument;
}
private Document testDoc2() throws ParserConfigurationException, IOException, SAXException {
String kmlString = "<?xml version=\"1.0\" encoding=\"UTF-8\"?><kml xmlns=\"http://www.opengis.net/kml/2.2\" xmlns:gx=\"http://www.google.com/kml/ext/2.2\"><Placemark><gx:Track><gx:coord>-122.207881 37.371915 156.000000</gx:coord></gx:Track></Placemark></kml>";
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
documentBuilderFactory.setNamespaceAware( true );
Document mDocument = documentBuilderFactory.newDocumentBuilder().parse( new InputSource( new StringReader( kmlString ) ) );
return mDocument;
}
private void test( Document mDocument ) throws Exception {
String xml = toXmlString( mDocument );
Log.d( "TEST-XML", xml );
XPath xPath = XPathFactory.newInstance().newXPath();
xPath.setNamespaceContext( new NamespaceContext() {
#Override
public String getNamespaceURI( String prefix ) {
switch( prefix ) {
case XMLConstants.DEFAULT_NS_PREFIX:
return "http://www.opengis.net/kml/2.2";
case "gx":
return "http://www.google.com/kml/ext/2.2";
}
return XMLConstants.NULL_NS_URI;
}
#Override
public String getPrefix( String namespaceURI ) {
return null;
}
#Override
public Iterator getPrefixes( String namespaceURI ) {
return null;
}
} );
NodeList result1 = (NodeList) xPath.evaluate( "/kml", mDocument, XPathConstants.NODESET );
Log.d( "TEST-RESULT1", String.valueOf( result1.getLength() ) );
NodeList result2 = (NodeList) xPath.evaluate( "/kml/Placemark", mDocument, XPathConstants.NODESET );
Log.d( "TEST-RESULT2", String.valueOf( result2.getLength() ) );
NodeList result3 = (NodeList) xPath.evaluate( "/kml/Placemark/gx:Track", mDocument, XPathConstants.NODESET );
Log.d( "TEST-RESULT3", String.valueOf( result3.getLength() ) );
}
The test() method executes 3 XPath statements/patterns and is called once for each of two test documents. The 2 documents are constructed using different methods but the contents should be identical. However, the results I get from the 3 XPath statements are different.
These are the results with document 1:
2018-11-17 17:51:28.289 22837-22837/ca.csdesigninc.offroadtracker D/TEST-XML: <?xml version="1.0" encoding="UTF-8"?><kml xmlns="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2"><Placemark><gx:Track><gx:coord>-122.207881 37.371915 156.000000</gx:coord></gx:Track></Placemark></kml>
2018-11-17 17:51:28.324 22837-22837/ca.csdesigninc.offroadtracker D/TEST-RESULT1: 1
2018-11-17 17:51:28.334 22837-22837/ca.csdesigninc.offroadtracker D/TEST-RESULT2: 1
2018-11-17 17:51:28.343 22837-22837/ca.csdesigninc.offroadtracker D/TEST-RESULT3: 0
and these are the results with document 2:
2018-11-17 17:51:28.348 22837-22837/ca.csdesigninc.offroadtracker D/TEST-XML: <?xml version="1.0" encoding="UTF-8"?><kml xmlns="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2"><Placemark><gx:Track><gx:coord>-122.207881 37.371915 156.000000</gx:coord></gx:Track></Placemark></kml>
2018-11-17 17:51:28.358 22837-22837/ca.csdesigninc.offroadtracker D/TEST-RESULT1: 0
2018-11-17 17:51:28.363 22837-22837/ca.csdesigninc.offroadtracker D/TEST-RESULT2: 0
2018-11-17 17:51:28.372 22837-22837/ca.csdesigninc.offroadtracker D/TEST-RESULT3: 0
There are at least 2 problems:
since the 2 documents are identical (I think), why are the results of the tests different? (i.e., the first 2 XPath statements succeed with document 1 but neither succeeds with document 2.)
and why does the 3rd XPath statement fail to find the gx:Track element in both document 1 and document 2?
UPDATE: This problem seems to have something to do with having
xmlns="http://www.opengis.net/kml/2.2"
included in document 2. If I remove it, the results of the first 2 XPath tests are the correct (for both documents) - and in fact XPath test 3 now works on document 2. Unfortunately, I still don't have a handle on this behavior.
I'm probably missing something obvious and would appreciate any help.

The differences are due to namespaces. Both in how the XML is being produced, and when you are selecting content in the XPath.
Unfortunately, it is difficult to see the difference because the XML that happens to be serialized by the toXmlString() for testDoc1() doesn't exactly match the state of the in-memory document.
When you construct the kml element, using createElement() it creates an element that is bound to the "no namespace". Then, you added namespace attributes, which happen to come out when serializing with toXmlString() and make the kml element appear to be in the http://www.opengis.net/kml/2.2 namespace.
If you were to marshal that XML back to a new Document object, the kml element would be bound to that namespace. However, the current in-memory object for that element is not.
You can observe this by adding some additional diagnostics println messages:
NodeList result1 = (NodeList) xPath.evaluate("/kml", mDocument, XPathConstants.NODESET);
System.out.println(String.valueOf(result1.getLength()));
System.out.println("Namespace URI: " + result1.item(0).getNamespaceURI());
System.out.println("Prefix: " + result1.item(0).getPrefix());
You can round-trip your XML and observe that it behaves different when you marshall the serialized XML:
private void test(Document mDocument) throws Exception {
String xml = toXmlString(mDocument);
System.out.println( xml);
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
documentBuilderFactory.setNamespaceAware(true);
mDocument = documentBuilderFactory.newDocumentBuilder().parse(new InputSource(new StringReader(xml)));
However, that's cheating. What you really want to do is ensure that the elements are created properly in the first place. When you create an element that you want to be bound to a namespace, use the createElementNS() method, as indicated in the JavaDoc comments for createElement():
To create an element with a qualified name and namespace URI, use the createElementNS method.
So, to create an element that is bound to the http://www.opengis.net/kml/2.2 namespace, you would want to use:
Element mKmlElement = mDocument.createElementNS("http://www.opengis.net/kml/2.2", "kml");
and:
Element mKmlElement = mDocument.createElementNS("http://www.opengis.net/kml/2.2", "Placemark");
and the same goes for the gx:Track element:
Element gxTrackElement = mDocument.createElementNS("http://www.google.com/kml/ext/2.2","gx:Track");
Once you get your Document objects truly equal and correct, you then need to adjust your XPath.
With XPath, if you don't apply a namespace prefix, it will select elements bound to the "no namespace". So, /kml will only select kml elements that are not bound to a namespace. But since your kml elements are bound to the http://www.opengis.net/kml/2.2 namespace, it won't select them.
In your override of the getNamespaceURI() function, you could reserve gx for the Google KML Extension namespace, and then default any other namespace-prefix to resolve to http://www.opengis.net/kml/2.2:
#Override
public String getNamespaceURI(String prefix) {
return "gx".equals(prefix) ? "http://www.google.com/kml/ext/2.2" : "http://www.opengis.net/kml/2.2";
}
Then, adjust your XPath statements to use a prefix for those KML elements. If you use the above code, it doesn't matter what prefix you use. Anything other than gx will return the http://www.opengis.net/kml/2.2 namespace.
NodeList result1 = (NodeList) xPath.evaluate("/k:kml", mDocument, XPathConstants.NODESET);
System.out.println(String.valueOf(result1.getLength()));
System.out.println("Namespace URI: " + result1.item(0).getNamespaceURI());
System.out.println("Prefix: " + result1.item(0).getPrefix());
NodeList result2 = (NodeList) xPath.evaluate("/k:kml/k:Placemark", mDocument, XPathConstants.NODESET);
System.out.println( String.valueOf(result2.getLength()));
NodeList result3 = (NodeList) xPath.evaluate("/k:kml/k:Placemark/gx:Track", mDocument, XPathConstants.NODESET);
System.out.println(String.valueOf(result3.getLength()));
Putting it all together:
public App() {
super();
try {
test( testDoc1() );
test( testDoc2() );
} catch( Exception e ) {
e.printStackTrace();
} finally {
Log.d( "TEST-FINISHED", "test is finished" );
}
}
private String toXmlString(Document document) throws TransformerException {
DOMSource domSource = new DOMSource(document);
StringWriter writer = new StringWriter();
StreamResult result = new StreamResult(writer);
TransformerFactory tf = TransformerFactory.newInstance();
Transformer transformer = tf.newTransformer();
transformer.transform(domSource, result);
return writer.toString();
}
private Document testDoc1() throws ParserConfigurationException {
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
documentBuilderFactory.setNamespaceAware(true);
Document mDocument = documentBuilderFactory.newDocumentBuilder().newDocument();
String XMLNS_NAMESPACE_URI = "http://www.w3.org/2000/xmlns/";
//Element mKmlElement = mDocument.createElement("kml");
Element mKmlElement = mDocument.createElementNS("http://www.opengis.net/kml/2.2", "kml");
//mKmlElement.setAttributeNS(XMLNS_NAMESPACE_URI, "xmlns", "http://www.opengis.net/kml/2.2");
mKmlElement.setAttributeNS(XMLNS_NAMESPACE_URI, "xmlns:gx", "http://www.google.com/kml/ext/2.2");
mDocument.appendChild(mKmlElement);
//Element mPlacemarkElement = mDocument.createElement("Placemark");
Element mPlacemarkElement = mDocument.createElementNS("http://www.opengis.net/kml/2.2", "Placemark");
//mPlacemarkElement.setAttributeNS(XMLNS_NAMESPACE_URI, "xmlns", "http://www.opengis.net/kml/2.2");
mKmlElement.appendChild(mPlacemarkElement);
//Element gxTrackElement = mDocument.createElement("gx:Track");
Element gxTrackElement = mDocument.createElementNS("http://www.google.com/kml/ext/2.2","gx:Track");
mPlacemarkElement.appendChild(gxTrackElement);
//Element gxCoordElement = mDocument.createElement("gx:coord");
Element gxCoordElement = mDocument.createElementNS("http://www.google.com/kml/ext/2.2", "gx:coord");
gxCoordElement.setTextContent("-122.207881 37.371915 156.000000");
gxTrackElement.appendChild(gxCoordElement);
return mDocument;
}
private Document testDoc2() throws ParserConfigurationException, IOException, SAXException {
String kmlString = "<?xml version=\"1.0\" encoding=\"UTF-8\"?><kml xmlns=\"http://www.opengis.net/kml/2.2\" xmlns:gx=\"http://www.google.com/kml/ext/2.2\"><Placemark><gx:Track><gx:coord>-122.207881 37.371915 156.000000</gx:coord></gx:Track></Placemark></kml>";
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
documentBuilderFactory.setNamespaceAware(true);
Document mDocument = documentBuilderFactory.newDocumentBuilder().parse(new
InputSource(new StringReader(kmlString)));
return mDocument;
}
private void test(Document mDocument) throws Exception {
String xml = toXmlString(mDocument);
System.out.println( xml);
XPath xPath = XPathFactory.newInstance().newXPath();
xPath.setNamespaceContext(new NamespaceContext() {
#Override
public String getNamespaceURI(String prefix) {
return "gx".equals(prefix) ? "http://www.google.com/kml/ext/2.2" : "http://www.opengis.net/kml/2.2";
}
#Override
public String getPrefix(String namespaceURI) {
if ("http://www.google.com/kml/ext/2.2".equals(namespaceURI)) {
return "gx";
}
return null;
}
#Override
public Iterator getPrefixes(String namespaceURI) {
List<String> ns = new ArrayList<>();
ns.add("gx");
return ns.iterator();
}
});
NodeList result1 = (NodeList) xPath.evaluate("/k:kml", mDocument, XPathConstants.NODESET);
System.out.println(String.valueOf(result1.getLength()));
System.out.println("Namespace URI: " + result1.item(0).getNamespaceURI());
System.out.println("Prefix: " + result1.item(0).getPrefix());
NodeList result2 = (NodeList) xPath.evaluate("/k:kml/k:Placemark", mDocument, XPathConstants.NODESET);
System.out.println( String.valueOf(result2.getLength()));
NodeList result3 = (NodeList) xPath.evaluate("/k:kml/k:Placemark/gx:Track", mDocument, XPathConstants.NODESET);
System.out.println(String.valueOf(result3.getLength()));
}

How to get an attribute within an Element ID

I have the following XML data. I would like to get the lat & lng values that only pertain to the location, not the southwest. How can I do this without having to also read the southwest.
`<geometry>
<location>
<lat>51.5739894</lat>
<lng>-0.1499698</lng>
</location>
<southwest>
<lat>51.5727314</lat>
<lng>-0.1511809</lng>
</southwest>
</geometry>`
So far, I've tried:
`
#Override
public void startElement(String uri, String localName, String qName, Attributes attributes){
if(localName.equals("location")){
Node n1 = new Node(
Double.parseDouble(attributes.getValue("lat"))
Double.parseDouble(attributes.getValue("lng"))
);
current = n1;
}
}`

If your xml is not huge, its ok if you use an approach using XPathFactory. Otherwise go for SAX parser. But you need to do extra processing when writing SAX parsers particularly when you ahve conditions like I want only location's lat value.
I would use an xpath approach, very simple to use, no need to use third party. It can be done via java.xml.*
Code would be :
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
Document doc = db.parse( new File( ".//input.xml" ) );
XPathFactory xPathFactory = XPathFactory.newInstance();
XPath xpath = xPathFactory.newXPath();
XPathExpression latExpr = xpath.compile( "//location/lat" );
XPathExpression lngExpr = xpath.compile( "//location/lng" );
Object exprEval = latExpr.evaluate( doc, XPathConstants.NUMBER );
if ( exprEval != null )
{
System.out.println( "Location's lat value is :" + exprEval );
}
exprEval = lngExpr.evaluate( doc, XPathConstants.NUMBER );
if ( exprEval != null )
{
System.out.println( "Location's lng value is :" + exprEval );
}
input.xml contains your xml.
It uses the xpath : //location/lat which means get me the value of lat whose parent is location.
And evaluate the xpath as a NUMBER.
Output is :
Location's lat value is :51.5739894
Location's lng value is :-0.1499698

For this particular case, if I were you I'll use org.json parse as JSONObject to query every node.
JSONObject jsonObject = XML.toJSONObject(xml).getJSONObject("geometry").getJSONObject("location");
String lat = jsonObject.getString("lat");
String lng = jsonObject.getString("lng");

Java XML JDOM2 XPath - Read text value from XML attribute and element using XPath expression

The program should be allowed to read from an XML file using XPath expressions.
I already started the project using JDOM2, switching to another API is unwanted.
The difficulty is, that the program does not know beforehand if it has to read an element or an attribute.
Does the API provide any function to receive the content (string) just by giving it the XPath expression?
From what I know about XPath in JDOM2, it uses objects of different types to evaluate XPath expressions pointing to attributes or elements.
I am only interested in the content of the attribute / element where the XPath expression points to.
Here is an example XML file:
<?xml version="1.0" encoding="UTF-8"?>
<bookstore>
<book category="COOKING">
<title lang="en">Everyday Italian</title>
<author>Giada De Laurentiis</author>
<year>2005</year>
<price>30.00</price>
</book>
<book category="CHILDREN">
<title lang="en">Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year>
<price>29.99</price>
</book>
<book category="WEB">
<title lang="en">XQuery Kick Start</title>
<author>James McGovern</author>
<author>Per Bothner</author>
<author>Kurt Cagle</author>
<author>James Linn</author>
<author>Vaidyanathan Nagarajan</author>
<year>2003</year>
<price>49.99</price>
</book>
<book category="WEB">
<title lang="en">Learning XML</title>
<author>Erik T. Ray</author>
<year>2003</year>
<price>39.95</price>
</book>
</bookstore>
This is what my program looks like:
package exampleprojectgroup;
import java.io.IOException;
import java.util.LinkedList;
import java.util.List;
import org.jdom2.Attribute;
import org.jdom2.Document;
import org.jdom2.Element;
import org.jdom2.JDOMException;
import org.jdom2.filter.Filters;
import org.jdom2.input.SAXBuilder;
import org.jdom2.input.sax.XMLReaders;
import org.jdom2.xpath.XPathExpression;
import org.jdom2.xpath.XPathFactory;
public class ElementAttribute2String
{
ElementAttribute2String()
{
run();
}
public void run()
{
final String PATH_TO_FILE = "c:\\readme.xml";
/* It is essential that the program has to work with a variable amount of XPath expressions. */
LinkedList<String> xPathExpressions = new LinkedList<>();
/* Simulate user input.
* First XPath expression points to attribute,
* second one points to element.
* Many more expressions follow in a real situation.
*/
xPathExpressions.add( "/bookstore/book/#category" );
xPathExpressions.add( "/bookstore/book/price" );
/* One list should be sufficient to store the result. */
List<Element> elementsResult = null;
List<Attribute> attributesResult = null;
List<Object> objectsResult = null;
try
{
SAXBuilder saxBuilder = new SAXBuilder( XMLReaders.NONVALIDATING );
Document document = saxBuilder.build( PATH_TO_FILE );
XPathFactory xPathFactory = XPathFactory.instance();
int i = 0;
for ( String string : xPathExpressions )
{
/* Works only for elements, uncomment to give it a try. */
// XPathExpression<Element> xPathToElement = xPathFactory.compile( xPathExpressions.get( i ), Filters.element() );
// elementsResult = xPathToElement.evaluate( document );
// for ( Element element : elementsResult )
// {
// System.out.println( "Content of " + string + ": " + element.getText() );
// }
/* Works only for attributes, uncomment to give it a try. */
// XPathExpression<Attribute> xPathToAttribute = xPathFactory.compile( xPathExpressions.get( i ), Filters.attribute() );
// attributesResult = xPathToAttribute.evaluate( document );
// for ( Attribute attribute : attributesResult )
// {
// System.out.println( "Content of " + string + ": " + attribute.getValue() );
// }
/* I want to receive the content of the XPath expression as a string
* without having to know if it is an attribute or element beforehand.
*/
XPathExpression<Object> xPathExpression = xPathFactory.compile( xPathExpressions.get( i ) );
objectsResult = xPathExpression.evaluate( document );
for ( Object object : objectsResult )
{
if ( object instanceof Attribute )
{
System.out.println( "Content of " + string + ": " + ((Attribute)object).getValue() );
}
else if ( object instanceof Element )
{
System.out.println( "Content of " + string + ": " + ((Element)object).getText() );
}
}
i++;
}
}
catch ( IOException ioException )
{
ioException.printStackTrace();
}
catch ( JDOMException jdomException )
{
jdomException.printStackTrace();
}
}
}
Another thought is to search for the '#' character in the XPath expression, to determine if it is pointing to an attribute or element.
This gives me the desired result, though I wish there was a more elegant solution.
Does the JDOM2 API provide anything useful for this problem?
Could the code be redesigned to meet my requirements?
Thank you in advance!

XPath expressions are hard to type/cast because they need to be compiled in a system that is sensitive to the return type of the XPath functions/values that are in the expression. JDOM relies on third-party code to do that, and that third party code does not have a mechanism to correlate those types at your JDOM code's compile time. Note that XPath expressions can return a number of different types of content, including String, boolean, Number, and Node-List-like content.
In most cases, the XPath expression return type is known before the expression is evaluated, and the programmer has the "right" casting/expectations for processing the results.
In your case, you don't, and the expression is more dynamic.
I recommend that you declare a helper function to process the content:
private static final Function extractValue(Object source) {
if (source instanceof Attribute) {
return ((Attribute)source).getValue();
}
if (source instanceof Content) {
return ((Content)source).getValue();
}
return String.valueOf(source);
}
This at least will neaten up your code, and if you use Java8 streams, can be quite compact:
List<String> values = xPathExpression.evaluate( document )
.stream()
.map(o -> extractValue(o))
.collect(Collectors.toList());
Note that the XPath spec for Element nodes is that the string-value is the concatination of the Element's text() content as well as all child elements' content. Thus, in the following XML snippet:
<a>bilbo <b>samwise</b> frodo</a>
the getValue() on the a element will return bilbo samwise frodo, but the getText() will return bilbo frodo. Choose which mechanism you use for the value extraction carefully.

I had the exact same problem and took the approach of recognizing when an attribute is the focus of the Xpath. I solved with two functions. The first complied the XPathExpression for later use:
XPathExpression xpExpression;
if (xpath.matches( ".*/#[\\w]++$")) {
// must be an attribute value we're after..
xpExpression = xpfac.compile(xpath, Filters.attribute(), null, myNSpace);
} else {
xpExpression = xpfac.compile(xpath, Filters.element(), null, myNSpace);
}
The second evaluates and returns a value:
Object target = xpExpression.evaluateFirst(baseEl);
if (target != null) {
String value = null;
if (target instanceof Element) {
Element targetEl = (Element) target;
value = targetEl.getTextNormalize();
} else if (target instanceof Attribute) {
Attribute targetAt = (Attribute) target;
value = targetAt.getValue();
}
I suspect its a matter of coding style whether you prefer the helper function suggested in the previous answer or this approach. Either will work.

Read values from a complex xml using java

HI I am new to Java and trying to read an XML file.
Here is my XML file :-
<?xml version="1.0" encoding="UTF-8"?>
<parameter>
<attribute>a</attribute>
Here is my code I am trying to read the key and value from the xml but I am stuck .Here is my code :-
public class TestDBMain {
public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
File file = new File("ACL.xml");
DocumentBuilderFactory dbfactory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = dbfactory.newDocumentBuilder();
Document doc = builder.parse(file);
NodeList nList = doc.getElementsByTagName("testCaseDataName");
for(int i = 0;i<nList.getLength();i++){
Node nNode = nList.item(i);
if(nNode.getNodeType()== Node.ELEMENT_NODE){
Element ele = (Element) nNode;
// System.out.println(ele.getTextContent());
//System.out.println(ele.getElementsByTagName("testCaseName").item(0).getTextContent());
System.out.println(ele.getAttributeNode("testCaseDataName"));
//I dont know which methods to use to print the key and value in the xml under parameter
}
}
}
}
Can anyone please help me with this

Disclaimer: I maintain the JDOM project, so I am biased.... but... this is an ideal use case for JDOM:
Document doc = new SAXBuilder().build(new File("ACL.xml"));
Element root = doc.getRootElement();
for (Element testcase : root.getChildren()) {
int id = Integer.parseInt(testcase.getChildText("id"));
String name = testcase.getChildText("testCaseName");
String expect = testcase.getChildText("expectedResult");
Map<String,String> params = new LinkedHashMap<String,String>();
Element parmemt = testcase.getChild("parameter");
if (parmemt != null) {
Iterator<Element> it = parmemt.getChildren().iterator();
while (it.hasNext()) {
Element key = it.next();
if (!"key".equals(key.getName())) {
throw new IllegalStateException("Expected key but got " + key);
}
if (!it.hasNext()) {
throw new IllegalStateException("Expected value for key " + key);
}
Element val = it.next();
if (!"value".equals(val.getName())) {
throw new IllegalStateException("Expected value but got " + val);
}
params.put(key.getValue(), val.getValue());
}
}
System.out.printf("Processing test case %d -> %s\n Expect %s\n Parameters: %s\n",
id, name, expect, params.toString());
}
For me this produces the output
Processing test case 1 -> EditTest
Expect nooptionsacltrue
Parameters: {}
Processing test case 2 -> AddTest
Expect featuresaddedacltrue
Parameters: {featues=w,f}
Processing test case 3 -> AddTest
Expect duplicateacltrue
Parameters: {projectType=NEW, Name=28HPM, status=ACTIVE, canOrder=Yes}

your code read <testCaseDataName> node. it is not go inside of this tag.
so try this..
for(int i = 0;i<nList.getLength();i++){
NodeList nodeList = nList.item(i).getChildNodes();
for(int j = 0;j<nList.getLength();j++){
Node nNode = nodeList.item(j);
if(nNode.getNodeType()== Node.ELEMENT_NODE){
System.out.println(nNode.getNodeName() +" : "+nNode.getTextContent());
if(nNode.getNodeName().equals("parameter")){
NodeList param = nNode.getChildNodes();
System.out.println(" "+param.item(0).getNodeName() +" : "+param.item(0).getTextContent());
System.out.println(" "+param.item(1).getNodeName() +" : "+param.item(1).getTextContent());
}
}
}
}