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reading xml file with multiple child node

Consider i have a XML file like the below xml file.
<top>
<CRAWL>
<NAME>div[class=name],attr=0</NAME>
<PRICE>span[class~=(?i)(price-new|price-old)],attr=0</PRICE>
<DESC>div[class~=(?i)(sttl dyn|bin)],attr=0</DESC>
<PROD_IMG>div[class=image]>a>img,attr=src</PROD_IMG>
<URL>div[class=name]>a,attr=href</URL>
</CRAWL>
<CRAWL>
<NAME>img[class=img],attr=alt</NAME>
<PRICE>div[class=g-b],attr=0</PRICE>
<DESC>div[class~=(?i)(sttl dyn|bin)],attr=0</DESC>
<PROD_IMG>img[itemprop=image],attr=src</PROD_IMG>
<URL>a[class=img],attr=href</URL>
</CRAWL>
</top>
what i want is first take all the values coming under and after finishing the first operation go to the next one and repeat it even though i have more than two tag.I have managed to get if just one is available. using the values coming inside the tags i am doing some other function. in each it has values from different and i am using that values for different operations. everything else if fine other than i dont know how to loop the fetching inside the xml file.
regards

If I'm understanding this correctly, you're trying to extract data from ALL tags that exist within your XML fragment. There are multiple solutions to this. I'm listing them below:
XPath: If you know exactly what your XML structure is, you can employ XPath for each node=CRAWL to find data within tags:
// Instantiate XPath variable
XPath xpath = XPathFactory.newInstance().newXPath();
// Define the exact XPath expressions you want to get data for:
XPathExpression name = xpath.compile("//top/CRAWL/NAME/text()");
XPathExpression price = xpath.compile("//top/CRAWL/PRICE/text()");
XPathExpression desc = xpath.compile("//top/CRAWL/DESC/text()");
XPathExpression prod_img = xpath.compile("//top/CRAWL/PROD_IMG/text()");
XPathExpression url = xpath.compile("//top/CRAWL/URL/text()");
At this point, each of the variables above will contain the data for each of the tags. You could drop this into an array for each where you will have all the data for each of the tags in all elements.
The other (more efficient solution) is to have the data stored by doing DOM based parsing:
// Instantiate the doc builder
DocumentBuilder xmlDocBuilder = domFactory.newDocumentBuilder();
Document xmlDoc = xmlDocBuilder.parse("xmlFile.xml");
// Create NodeList of element tag "CRAWL"
NodeList crawlNodeList = xmlDoc.getElementsByTagName("CRAWL");
// Now iterate through each item in the NodeList and get the values of
// each of the elements in Name, Price, Desc etc.
for (Node node: crawlNodeList) {
NamedNodeMap subNodeMap = node.getChildNodes();
int currentNodeMapLength = subNodeMap.getLength();
// Get each node's name and value
for (i=0; i<currentNodeMapLength; i++){
// Iterate through all of the values in the nodeList,
// e.g. NAME, PRICE, DESC, etc.
// Do something with these values
}
}
Hope this helps!

Parse XML file using XPATH expressions and Java

I would like to parse an xml file and i'm using Java and xpath evaluation.
I would like to output the current's node sibling with an xpath expression and without
using getNextSibling() function, is that possible?
e.g. if we read the name element i would like to add the xpath expression ="./address"
in order to output the sibling of "name" without using getNextSibling()/.
The xml file is as follows:
<root>
<name>
<address>
<profession>
</root>
My code is as follows:
package dom_stack4;
import org.w3c.dom.*;
import javax.xml.xpath.*;
import javax.xml.parsers.*;
import java.io.IOException;
import org.xml.sax.SAXException;
public class Dom_stack4 {
public static void main(String[] args) throws ParserConfigurationException, SAXException,
IOException, XPathExpressionException {
// TODO code application logic here
DocumentBuilderFactory domFactory =
DocumentBuilderFactory.newInstance();
domFactory.setNamespaceAware(true);
DocumentBuilder builder = domFactory.newDocumentBuilder();
Document doc = builder.parse("root.xml");
XPath xpath = XPathFactory.newInstance().newXPath();
// XPath Query for showing all nodes value
XPathExpression expr = xpath.compile("/root/name/text()");
Object result = expr.evaluate(doc, XPathConstants.NODESET);
NodeList nodes = (NodeList) result;
for (int i = 0; i < nodes.getLength(); i++) {
System.out.println(" Name is : " + nodes.item(i).getNodeValue());
/* IS that possible here ?? */
/* ./address/text() => outputs the current's node sibling */
expr = xpath.compile("./address/text()");
Object result1 = expr.evaluate(doc, XPathConstants.NODESET);
NodeList nodes1 = (NodeList) result1;
for (int j = 0; j < nodes1.getLength(); j++) {
System.out.println(" ---------------- " + nodes1.item(j).getNodeValue());
}
}
}
}
Thanks, in advance

First off, it would be good if you were running your code using properly formed xml, the name address and profession tags should be closed or you will get an error when you try to parse it. Secondly, if you want to select the text child of the node, you need to make sure there is actually something there, so your xml should look something like this:
<root>
<name>hi</name>
<address>hi</address>
<profession>hi</profession>
</root>
Now, what you have for selecting the text of the name element is fine, so starting with your IS that possible here ?? comment there are some changes you need to make.
If you want to evaluate a relative XPath, you don't want to be passing your document object to the XPath's evaluate method. The current location that the XPath is being evaluated from is determined by the item that you give to it, and the document object is always evaluated at the root. If you want to evaluate relative to a specific node, rather than giving it the document, give it that node.
So you would have something like this for your evaluate method call:
Object result1 = expr.evaluate(nodes.item(i), XPathConstants.NODESET);
Next, you should make sure that your XPath is actually correct. The node that we currently have selected is the text node of name. Which means we need to first go to the name node instead of the text node. The . expression in XPath syntax selects the current node, so all you are doing with that is selecting the same node. You want the .. expression which selects the parent node.
So with our current XPath of .. we are selecting the name node. What we want to do is select address nodes that are sibilings of the name node. There are two ways we can do this, we could select the parent of the name node, the root node, and select address nodes that are children of that, or we could use an XPath axis to select the siblings (information about axes can be found here http://www.w3schools.com/xpath/xpath_axes.asp)
If we are going through the root node, we would need to select the parent of the parent of our current node so ../.. which gives us the root node, followed by the address children: ../../address/text(), which would give us all address siblings.
Alternatively, using an axis, we could do .. to select the name node followed by ../following-sibling::address (NOTE: this only works if the address nodes are after the name node) and then select the text of the address nodes with ../following-sibling:address/text().
This gives us those two lines as either
expr = xpath.compile("../../address/text()");
Object result1 = expr.evaluate(nodes.item(i), XPathConstants.NODESET);
or
expr = xpath.compile("../following-sibling::address/text()");
Object result1 = expr.evaluate(nodes.item(i), XPathConstants.NODESET);

JAXP XPath 1.0 or 2.0 - how to distinguish empty strings from non-existent values

Given the following XML instance:
<entities>
<person><name>Jack</name></person>
<person><name></name></person>
<person></person>
</entities>
I am using the following code to: (a) iterate over the persons and (b) obtain the name of each person:
XPathExpression expr = xpath.compile("/entities/person");
NodeList nodes = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);
for (int i = 0 ; i < nodes.getLength() ; i++) {
Node node = nodes.item(i);
String innerXPath = "name/text()";
String name = xpath.compile(innerXPath).evaluate(node);
System.out.printf("%2d -> name is %s.\n", i, name);
}
The code above is unable to distinguish between the 2nd person case (empty string for name) and the 3rd person case (no name element at all) and simply prints:
0 -> name is Jack.
1 -> name is .
2 -> name is .
Is there a way to distinguish between these two cases using a different innerXPath expression? In this SO question it seems that the XPath way would be to return an empty list, but I 've tried that too:
String innerXPath = "if (name) then name/text() else ()";
... and the output is still the same.
So, is there a way to distinguish between these two cases with a different innerXPath expression? I have Saxon HE on my classpath so I can use XPath 2.0 features as well.
Update
So the best I could do based on the accepted answer is the following:
XPathExpression expr = xpath.compile("/entities/person");
NodeList nodes = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);
for (int i = 0 ; i < nodes.getLength() ; i++) {
Node node = nodes.item(i);
String innerXPath = "name";
NodeList names = (NodeList) xpath.compile(innerXPath).evaluate(node, XPathConstants.NODESET);
String nameValue = null;
if (names.getLength()>1) throw new RuntimeException("impossible");
if (names.getLength()==1)
nameValue = names.item(0).getFirstChild()==null?"":names.item(0).getFirstChild().getNodeValue();
System.out.printf("%2d -> name is [%s]\n", i, nameValue);
}
The above code prints:
0 -> name is [Jack]
1 -> name is []
2 -> name is [null]
In my view this is not very satisfactory as logic is spread in both XPath and Java code and limits the usefulness of XPath as a host language and API-agnostic notation. My particular use case was to just keep a collection of XPaths in a property file and evaluate them at runtime in order to obtain the information I need without any ad-hoc extra handling. Apparently that's not possible.

The JAXP API, being based on XPath 1.0, is pretty limited here. My instinct would be to return the Name element (as a NodeList). So the XPath expression required is simply "Name". Then cases 1 and 2 will return a nodelist of length 1, while case 3 will return a nodelist of length 0. Cases 1 and 2 can then easily be distinguished within the application by getting the value of the node and testing whether it is zero-length.
Using /text() is always best avoided anyway, since it causes your query to be sensitive to the presence of comments in the XML.

As a long-time user of Saxon XSLT, I'm pleased to find once again that I like Michael Kay's recommendation here. Generally, I like the pattern of returning a collection for queries, even for queries that are expected to return only at most one instance.
What I don't like doing is having to open a bundled interface to try to solve a particular need and then finding that one has to reimplement much of what the original interface handled.
Therefore, here's a method that uses Michael's recommendation while avoiding the cost of having to reimplement a Node-to-String transformation that is recommended in other comments in this thread.
#Nonnull
public Optional<String> findString( #Nonnull final String expression )
{
try
{
// for XpathConstants.STRING XPath returns an empty string for both values of no length
// and for elements that are not present.
// therefore, ask for a NODESET and then retrieve the first Node if any
final FluentIterable<Node> matches =
IterableNodeList.from( (NodeList) xpath.evaluate( expression, node, XPathConstants.NODESET ) );
if ( matches.isEmpty() )
{
return Optional.absent();
}
final Node firstNode = matches.first().get();
// now let XPath process a known-to-exist Node to retrieve its String value
return Optional.fromNullable( (String) xpath.evaluate( ".", firstNode, XPathConstants.STRING ) );
}
catch ( XPathExpressionException xee )
{
return Optional.absent();
}
}
Here, XPath.evaluate is called a second time to do whatever it usually does to transform the first found Node to the requested String value. Without this, there is a risk that a re-implementation will yield a different result than a direct call for an XPathConstant.STRING over the same source node and for the same expression.
Of course, this code is using Guava Optional and FluentIterable to make the intention more explicit. If you don't want Guava, use Java 8 or refactor the implementation using nulls and NodeList's own collection methods.

How to retrieve specific element (or nodelist) within an existing element from DOM in Java

I am trying to parse an XML file which contains multiple records of name A. Each A has multiple group records with name B . The various records within B have names x, y and z.
My questions are:
How do I navigate to B and
how do I obtain all values of x in loop.
The DOM is set to the document (i.e. elements of name "A")
I am using a DOM parser in Java.
Sample record:
<A>
<B><x>123</x><y>asdf</y><z>A345</z></B>
<B><x>987</x><y>ytre</y><z>Z959</z></B>
</A>

Document yourDom = ....;
XPathFactory xpf = XPathFactory.newInstance();
XPath xp = xpf.newXPath();
XPathExpression xpe = xp.compile("//A/B/*");
NodeList nodes = (NodeList) xpe.evaluate(yourDom, XPathConstants.NODESET);

Apart from using the standard DOM API directly which is usually a bit verbose for these tasks, you could also use jOOX as a jquery-like wrapper for DOM. Here's an example how to use it:
// Loop over all x element values within B using css-style selectors
for (String x : $(document).find("B x").texts()) {
// ...
}
// Loop over all x element values within B using XPath
for (String x : $(document).xpath("//B/x").texts()) {
// ...
}
// Loop over all x element values within B using the jOOX API
for (String x : $(document).find("B").children("x").texts()) {
// ...
}

XPath query returns duplicate nodes

I have a SOAP response that I'm processing in Java. It has a element with several different child elements. I'm using the following code to try to grab all of the bond nodes and find which one has a child tag with a value of ACTIVE. The NodeList returned by the initial evaluate statement contains 4 nodes, which is the correct number of children in the SOAP response, but they are all duplicates of the first element. Here is the code:
NodeList nodes = (NodeList)xpath.evaluate("//:bond", doc, XPathConstants.NODESET);
for(int i = 0; i < nodes.getLength(); i++){
HashMap<String, String> map = new HashMap<String, String>();
Element bond = (Element)nodes.item(i);
// Get only active bonds
String status = xpath.evaluate("//:status", bond);
String id = xpath.evaluate("//:instrumentId", bond);
if(!status.equals("ACTIVE"))
continue;
map.put("isin", xpath.evaluate(":isin", bond));
map.put("cusip", xpath.evaluate(":cusip", bond));
}
Thanks for your help,
Jared

The answer to your immediate question is that expressions like //:status will ignore the node that you pass in, and start from the root of the document.
However, there's probably an easier solution than what you've got, by using XPath to apply the test to the node. I think this should work, although it might contain typos (in particular, I can't remember whether text() can stand on its own or must be used in a predicate expression):
//:bond/:status[text()='ACTIVE']/..