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XML parsing in Java

How to parse XML below in Java using DOM Parser:
<employees>
<employee id="111">
<firstName>Rakesh</firstName>
<lastName>Mishra</lastName>
<location>Bangalore</location>
</employee>
<employee id="112">
<firstName>John</firstName>
<lastName>Davis</lastName>
<location>Chennai</location>
</employee>
<employee id="113">
<firstName>Rajesh</firstName>
<lastName>Sharma</lastName>
<location>Pune</location>
</employee>
</employees>

mccarl

Where is this XML coming from? A file, a database, the web, or hardcoded in your Java program? Assuming that this may be in a file, parsing is as simple as this...

DocumentBuilder documentBuilder = DocumentBuilderFactory.newInstance().newDocumentBuilder();

Document doc = documentBuilder.parse(new FileInputStream("my_xml_file.xml"));

// Do something useful with "doc"

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Vakils

ASKER

XML comes from file. Reading nodes value, is what I want. XML elements have no attributes at this stage and some elements may not any have value. For example while traversing XML tree, if an element has no value, I get null pointer exception in element.getTextContent(). Is there a elegant way to know that element has no value, rather than checking if element is null?

XML:
<contracts>
<contract>123</contract> // OK
<contract_year></contract_year> //exception
</contracts>
//Iterating through the nodes and extracting the data.
NodeList nodeList = document.getDocumentElement().getChildNodes();

for (int i = 0; i < nodeList.getLength(); i++) {

//We have encountered an <employee> tag.
Node node = nodeList.item(i);
if (node instanceof Element) {
Employee emp = new Employee();
emp.id = node.getAttributes().
getNamedItem("id").getNodeValue();

NodeList childNodes = node.getChildNodes();
for (int j = 0; j < childNodes.getLength(); j++) {
Node cNode = childNodes.item(j);

//Identifying the child tag of employee encountered.
if (cNode instanceof Element) {
String content = cNode.getLastChild().getTextContent().trim(); // null pointer exception if element has no value

Vakils

ASKER

XML:
<employee>
<Name>SAM</Name> // OK
<Middle></Middle> //exception
</employee>
//Iterating through the nodes and extracting the data.
NodeList nodeList = document.getDocumentElement().getChildNodes();

for (int i = 0; i < nodeList.getLength(); i++) {

//We have encountered an <employee> tag.
Node node = nodeList.item(i);
if (node instanceof Element) {
Employee emp = new Employee();
emp.id = node.getAttributes().
getNamedItem("id").getNodeValue();

NodeList childNodes = node.getChildNodes();
for (int j = 0; j < childNodes.getLength(); j++) {
Node cNode = childNodes.item(j);

//Identifying the child tag of employee encountered.
if (cNode instanceof Element) {
String content = cNode.getLastChild().getTextContent().trim(); // null pointer exception if element has no value

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mccarl

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Vakils

ASKER

OK. Got it. Calling trim is OK. getLastChild is not needed.
Thanks!

mccarl

Not a problem, glad to help! :)