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How to extract data from <dc> tag in java?

I am currently trying to extract the tag element < dc:title > from an epub in Java. However, i tried using
doc.getDocumentElement().getElementsByTagName("dc:title"));
and it only showed 2nd element :com.sun.org.apache.xerces.internal.dom.DeepNodeListImpl. I would like to know how can I extract < dc:tittle > ?
Here is my code:
File fXmlFile = new File("file directory");
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(fXmlFile);
doc.getDocumentElement().normalize();
System.out.println("1st element :" + doc.getElementsByTagName("dc");
System.out.println("2nd element :" + doc.getDocumentElement().getElementsByTagName("dc:title"));
System output:
1st element : com.sun.org.apache.xerces.internal.dom.DeepNodeListImpl#4f53e9be
2nd element :com.sun.org.apache.xerces.internal.dom.DeepNodeListImpl#e16e1a2
Added Sample Data
<dc:title>
<![CDATA[someData]]>
</dc:title>
<dc:creator>
<![CDATA[someData]>
</dc:creator>
<dc:language>someData</dc:language>

The method getElementsByTagName(String) is return a List of matching elements (note plural 's'). You then need to specify which element (such as by using .item(index) to access a Node instance) you want to use. Therewith, you can using getNodeValue() on that Node object.
EDITED: because of the CDATA element, rather use Node.getTextContent():
NodeList elems = doc.getElementsByTagName("dc:title");
Node item = elems.item(0);
System.out.println(item.getTextContent());

I would suggest using xpath to get the desired output.
Also, refer following link for examples.
https://www.journaldev.com/1194/java-xpath-example-tutorial
For example:
XPath xPath = XPathFactory.newInstance().newXPath();
String expression = "//dc:title/text()";
NodeList nodes = (NodeList) xPath.compile(expression).evaluate(doc, XPathConstants.NODESET);
System.out.println(nodes.item(0).getNodeValue());

How to select all child nodes from a parent node from xml if there are many parents node with same name?

<?xml version="1.0" encoding="UTF-8"?>
<invoice>
<obs>
<ob>
<code>ABC</code>
</ob>
<ob>
<code>123</code>
</ob>
</obs>
</invoice>
<invoice>
<obs>
<ob>
<code>DEF</code>
</ob>
</obs>
</invoice>
</invoices>
Question:
I have that xml, which will come to me from external system ,it can have large number of invoice nodes and one invoice node can have large number of 'code' nodes. I want to read the code nodes of all 'invoice' nodes and save them in an array like this :
invoice[1].code[1]=ABC
invoice[1].code[2]=123
invoice[2].code[1]=DEF
How to do this using XPathExpression in JAVA. My code is below which is not working.
expr = xpath.compile("//invoices/invoice/obs/ob/code/text()");
result1=expr.evaluate(dc, XPathConstants.NODESET);
nodes =(NodeList)result1;
Please give some general solution in case of number of nodes are high.

It will give both as there are two invoices try to give id to your xml like
<invoices>
<invoice name="invoice1">
<obs>
<ob>
<code>ABC</code>
</ob>
</obs>
</invoice>
<invoice name="invoice2">
<obs>
<ob>
<code>DEF</code>
</ob>
</obs>
</invoice>
</invoices>
then
expr = xpath.compile("//invoices[#name='invoice1']/invoice/obs/ob/code/text()");

you could try this xpath:
//invoices/invoice[descendant::code[.='ABC']]/obs/ob/code

There are 2 nodes where your xpath passes. You can try this.
String xml = "<invoices><invoice><obs><ob><code>ABC</code></ob><ob><code>111</code></ob></obs></invoice><invoice><obs><ob><code>DEF</code></ob></obs></invoice></invoices>";
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder =factory.newDocumentBuilder();
Document document = builder.parse(new InputSource(new StringReader(xml)));
XPathFactory xpathFactory = XPathFactory.newInstance();
Map<String,List<String>> invoiceCodeMap = new LinkedHashMap<>();
XPathExpression invoiceXpathExp = xpathFactory.newXPath().compile("//invoices/invoice");
NodeList invoiceNodes = (NodeList) invoiceXpathExp.evaluate(document, XPathConstants.NODESET);
//Iterate Invoice nodes
for(int invoiceIndex=0;invoiceIndex<invoiceNodes.getLength();invoiceIndex++){
String invoiceID = "invoice"+(invoiceIndex+1);
List<String> codeList = new ArrayList<>();
XPathExpression codeXpathExp = xpathFactory.newXPath().compile("obs/ob/code/text()");
NodeList codeNodes = (NodeList) codeXpathExp.evaluate(invoiceNodes.item(invoiceIndex), XPathConstants.NODESET);
for(int codeIndex=0;codeIndex<codeNodes.getLength();codeIndex++){
Node code = codeNodes.item(codeIndex);
codeList.add(code.getTextContent());
}
invoiceCodeMap.put(invoiceID, codeList);
}
System.out.println(invoiceCodeMap);

Getting the value of an attribute in Java from a XML using XPath

I'm currently using XPath to get some information from a podcast feed using Java and XPath. I'm trying to read the attribute of a node:
<?xml version="1.0" encoding="UTF-8"?>
<rss xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:sy="http://purl.org/rss/1.0/modules/syndication/" xmlns:admin="http://webns.net/mvcb/" xmlns:atom="http://www.w3.org/2005/Atom/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:content="http://purl.org/rss/1.0/modules/content/" xmlns:itunes="http://www.itunes.com/dtds/podcast-1.0.dtd" version="2.0">
<channel>
[....]
<itunes:image href="http://icebox.5by5.tv/images/broadcasts/14/cover.jpg" />
[...]
I want to get the value of the href attribute in <itunes:image>. Currently, I'm using the following code:
private static String IMAGE_XPATH = "//channel/itunes:image/#href";
String imageUrl = xpath.compile(IMAGE_XPATH).evaluate(doc, XPathConstants.STRING).toString();
The result of imageUrl is null. What happens in the code? Do I have an error in the XPath code, or in the Java code?
Thanks! :)

Disable namespace awarness:
DocumentBuilderFactory xmlFact = DocumentBuilderFactory.newInstance();
xmlFact.setNamespaceAware(false);
Your xpath expression should look like this now:
"//channel/image/#href"
If you need to use it as namespace aware, just implement your own NameSpaceContext, should look like this:
NamespaceContext ctx = new ItunesNamespaceContext();
XPathFactory xpathFact = XPathFactory.newInstance();
XPath xpath = xpathFact.newXPath();
xpath.setNamespaceContext(ctx);
String IMAGE_XPATH = "//channel/itunes:image/#href";
String imageUrl = path.compile(IMAGE_XPATH).evaluate(doc,XPathConstants.STRING).toString();
EDIT: Here is a test code that proves my point:
String a ="<?xml version=\"1.0\" encoding=\"UTF-8\"?><rss xmlns:dc=\"http://purl.org/dc/elements/1.1/\" xmlns:sy=\"http://purl.org/rss/1.0/modules/syndication/\" xmlns:admin=\"http://webns.net/mvcb/\" xmlns:atom=\"http://www.w3.org/2005/Atom/\" xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\" xmlns:content=\"http://purl.org/rss/1.0/modules/content/\" xmlns:itunes=\"http://www.itunes.com/dtds/podcast-1.0.dtd\" version=\"2.0\"><channel><itunes:image href=\"http://icebox.5by5.tv/images/broadcasts/14/cover.jpg\" /></channel></rss>";
DocumentBuilderFactory xmlFact = DocumentBuilderFactory.newInstance();
xmlFact.setNamespaceAware(false);
DocumentBuilder builder = xmlFact.newDocumentBuilder();
XPathFactory xpathFactory = XPathFactory.newInstance();
String expr = "//channel/image/#href";
XPath xpath = xpathFactory.newXPath();
Document doc = builder.parse(new InputSource(new StringReader(a)));
String imageUrl = (String) xpath.compile(expr).evaluate(doc ,XPathConstants.STRING);
System.out.println(imageUrl);
The output is:
http://icebox.5by5.tv/images/broadcasts/14/cover.jpg

The XPath should include the root element, so rss/channel/itunes:image/#href.
Alternatively, you could start the xpath with a // so that all levels are searched for the xpath (//channel/itunes:image/#href) but if the root will always be the same it is more efficient to use the first option.

how to get a node value in Xpath - Java

I've got a section of XML that looks like this:
<entry>
<id>tag:example.com,2005:Release/343597</id>
<published>2012-04-10T11:29:19Z</published>
<updated>2012-04-10T12:04:41Z</updated>
<link type="text/html" href="http://example.com/projects/example1" rel="alternate"/>
<title>example1</title>
</entry>
I need to grab the link http://example.com/projects/example1 from this block. I'm not sure how to do this. To get the title of the project I use this code:
String title1 = children.item(9).getFirstChild().getNodeValue();
where children is the getChildNodes() object for the <entry> </entry> block. But I keep getting NullPointerExceptions when I try to get the node value for the <link> node in a similar way. I see that the XML code is different for the <link> node, and I'm not sure what it's value is.... Please advise!

The xpath expression to get that node is
//entry/link/#href
In java you can write
Document doc = ... // your XML document
XPathExpression xp = XPathFactory.newInstance().newXPath().compile("//entry/link/#href");
String href = xp.evaluate(doc);
Then if you need to get the link value of the entry with a specific id you can change the xpath expression to
//entry[id='tag:example.com,2005:Release/343597']/link/#href
Finally if you want to get all the links in the documents, if the document has many entry elements you can write
Document doc = ... // your XML document
XPathExpression xp = XPathFactory.newInstance().newXPath().compile("//entry/link/#href");
NodeList links = (NodeList) xp.evaluate(doc, XPathConstants.NODESET);
// and iterate on links

Here is the complete code:
DocumentBuilderFactory domFactory = DocumentBuilderFactory
.newInstance();
domFactory.setNamespaceAware(true);
DocumentBuilder builder = domFactory.newDocumentBuilder();
Document doc = builder.parse("test.xml");
XPath xpath = XPathFactory.newInstance().newXPath();
XPathExpression expr = xpath.compile("//entry/link/#href");
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));
}

Stuck with XPath

Can somebody find what is wrong with this code. It always returns o nodes no matter whatever XPath I chose
DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
domFactory.setNamespaceAware(true);
domFactory.setIgnoringComments(true);
domFactory.setIgnoringElementContentWhitespace(true);
DocumentBuilder builder = domFactory.newDocumentBuilder();
Document dDoc = builder.parse("P:/MyBooks.xml");
NodeList myNodes = (NodeList) xpath.evaluate("//Title", dDoc, XPathConstants.NODESET);
System.out.println(myNodes.getLength());
MyBookx.xml is:
<?xml version="1.0" encoding="UTF-8"?>
<Books>
<Title attrib="title1"/>
<Title attrib="title2"/>
<Title attrib="title3"/>
</Books>

I was doing a big mistake. My xml doc was using default namespace while I am setting NamespaceAware(true) in docFactory. So I set NamespaceAware(false) and my problem is solved