{"id":8543,"date":"2014-01-27T22:44:37","date_gmt":"2014-01-27T20:44:37","guid":{"rendered":"http:\/\/examples.javacodegeeks.com\/?p=8543"},"modified":"2021-02-16T12:31:35","modified_gmt":"2021-02-16T10:31:35","slug":"java-xml-parser-tutorial","status":"publish","type":"post","link":"https:\/\/examples.javacodegeeks.com\/java-xml-parser-tutorial\/","title":{"rendered":"Java XML parser Tutorial"},"content":{"rendered":"

In this tutorial, we will discuss the Java XML parser or how to read XML files. XML is a markup language that defines a set of rules for encoding documents. Java offers a number of libraries in order to parse and process XML documents. Java xml parser examples provides the required functionality to read and modify an XML file.<\/p>\n

The XML language is used to provide a general way in order for different machines to communicate and exchange data. Like Java, XML is also platform independent. An XML document consists of elements. Each element has a start tag, its content and an end tag. Also, an XML document must have exactly one root element. Finally, an XML file has a strict syntax and form.<\/p>\n

1. Example of an XML File<\/h2>\n

In the following java XML parser examples, we will declare the employees of a company. Each employee has a unique ID, first and last name, age, and salary. The employees are separated by their IDs. We create a new file called Employees.xml<\/code> as shown below:<\/p>\n

Employees.xml<\/span><\/i><\/p>\n

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<?<\/code>xml<\/code> version<\/code>=<\/code>\"1.0\"<\/code> encoding<\/code>=<\/code>\"UTF-8\"<\/code>?><\/code><\/div>\n
<<\/code>Employees<\/code>><\/code><\/div>\n
     <\/code><<\/code>Employee<\/code> ID<\/code>=<\/code>\"1\"<\/code>><\/code><\/div>\n
          <\/code><<\/code>Firstname<\/code>>Lebron<\/<\/code>Firstname<\/code> ><\/code><\/div>\n
          <\/code><<\/code>Lastname<\/code>>James<\/<\/code>Lastname<\/code>><\/code><\/div>\n
          <\/code><<\/code>Age<\/code>>30<\/<\/code>Age<\/code>><\/code><\/div>\n
          <\/code><<\/code>Salary<\/code>>2500<\/<\/code>Salary<\/code>><\/code><\/div>\n
     <\/code><\/<\/code>Employee<\/code>><\/code><\/div>\n
     <\/code><<\/code>Employee<\/code> ID<\/code>=<\/code>\"2\"<\/code>><\/code><\/div>\n
          <\/code><<\/code>Firstname<\/code>>Anthony<\/<\/code>Firstname<\/code>><\/code><\/div>\n
          <\/code><<\/code>Lastname<\/code>>Davis<\/<\/code>Lastname<\/code>><\/code><\/div>\n
          <\/code><<\/code>Age<\/code>>22<\/<\/code>Age<\/code>><\/code><\/div>\n
          <\/code><<\/code>Salary<\/code>>1500<\/<\/code>Salary<\/code>><\/code><\/div>\n
     <\/code><\/<\/code>Employee<\/code>><\/code><\/div>\n
     <\/code><<\/code>Employee<\/code> ID<\/code>=<\/code>\"3\"<\/code>><\/code><\/div>\n
          <\/code><<\/code>Firstname<\/code>>Paul<\/<\/code>Firstname<\/code>><\/code><\/div>\n
          <\/code><<\/code>Lastname<\/code>>George<\/<\/code>Lastname<\/code>><\/code><\/div>\n
          <\/code><<\/code>Age<\/code>>24<\/<\/code>Age<\/code>><\/code><\/div>\n
          <\/code><<\/code>Salary<\/code>>2000<\/<\/code>Salary<\/code>><\/code><\/div>\n
     <\/code><\/<\/code>Employee<\/code>><\/code><\/div>\n
     <\/code><<\/code>Employee<\/code> ID<\/code>=<\/code>\"4\"<\/code>><\/code><\/div>\n
          <\/code><<\/code>Firstname<\/code>>Blake<\/<\/code>Firstname<\/code>><\/code><\/div>\n
          <\/code><<\/code>Lastname<\/code>>Griffin<\/<\/code>Lastname<\/code>><\/code><\/div>\n
          <\/code><<\/code>Age<\/code>>25<\/<\/code>Age<\/code>><\/code><\/div>\n
          <\/code><<\/code>Salary<\/code>>2250<\/<\/code>Salary<\/code>><\/code><\/div>\n
     <\/code><\/<\/code>Employee<\/code>><\/code><\/div>\n
<\/<\/code>Employees<\/code>><\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

Also, in order to capture the notion of an employee, we create its respective Java class, called Employee.java<\/code> as shown below:<\/p>\n

Employee.java:<\/span><\/i><\/p>\n

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class<\/code> Employee {<\/code><\/div>\n
 <\/div>\n
     <\/code>private<\/code> String ID;<\/code><\/div>\n
     <\/code>private<\/code> String Firstname;<\/code><\/div>\n
     <\/code>private<\/code> String Lastname;<\/code><\/div>\n
     <\/code>private<\/code> int<\/code> age;<\/code><\/div>\n
     <\/code>private<\/code> double<\/code> salary;<\/code><\/div>\n
 <\/div>\n
     <\/code>public<\/code> Employee(String ID, String Firstname, String Lastname, <\/code>int<\/code> age, <\/code>double<\/code> salary) {<\/code><\/div>\n
          <\/code>this<\/code>.ID = ID;<\/code><\/div>\n
          <\/code>this<\/code>.Firstname = Firstname;<\/code><\/div>\n
          <\/code>this<\/code>.Lastname = Lastname;<\/code><\/div>\n
          <\/code>this<\/code>.age = age;<\/code><\/div>\n
          <\/code>this<\/code>.salary = salary;<\/code><\/div>\n
     <\/code>}<\/code><\/div>\n
 <\/div>\n
     <\/code>@Override<\/code><\/div>\n
     <\/code>public<\/code> String toString() {<\/code><\/div>\n
          <\/code>return<\/code> \"<\"<\/code> + ID + <\/code>\", \"<\/code> + Firstname + <\/code>\", \"<\/code> + Lastname + <\/code>\", \"<\/code> + age + <\/code>\", \"<\/code><\/div>\n
                                   <\/code>+ salary + <\/code>\">\"<\/code>;<\/code><\/div>\n
     <\/code>}<\/code><\/div>\n
}<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

2. Parse an XML File using the DOM Parser<\/h2>\n

The DOM parser implementation is included in the release of JDK. The Document Object Model provides APIs that let you create, modify, delete, and rearrange nodes. The DOM parser parses the entire XML document and loads the XML content into a Tree structure. Using the Node<\/a><\/code> and NodeList<\/a><\/code> classes, we can retrieve and modify the content of an XML file.<\/p>\n

A sample example that loads the content of an XML file and prints its contents is shown below:<\/p>\n

DomParserExample.java:<\/span><\/i><\/p>\n

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import<\/code> java.io.File;<\/code><\/div>\n
import<\/code> java.io.IOException;<\/code><\/div>\n
import<\/code> java.util.ArrayList;<\/code><\/div>\n
import<\/code> java.util.List;<\/code><\/div>\n
 <\/div>\n
import<\/code> javax.xml.parsers.DocumentBuilder;<\/code><\/div>\n
import<\/code> javax.xml.parsers.DocumentBuilderFactory;<\/code><\/div>\n
import<\/code> javax.xml.parsers.ParserConfigurationException;<\/code><\/div>\n
 <\/div>\n
import<\/code> org.w3c.dom.Document;<\/code><\/div>\n
import<\/code> org.w3c.dom.Element;<\/code><\/div>\n
import<\/code> org.w3c.dom.Node;<\/code><\/div>\n
import<\/code> org.w3c.dom.NodeList;<\/code><\/div>\n
import<\/code> org.xml.sax.SAXException;<\/code><\/div>\n
 <\/div>\n
public<\/code> class<\/code> DomParserExample {<\/code><\/div>\n
 <\/div>\n
     <\/code>public<\/code> static<\/code> void<\/code> main(String[] args) <\/code>throws<\/code> ParserConfigurationException,<\/code><\/div>\n
          <\/code>SAXException, IOException {<\/code><\/div>\n
 <\/div>\n
          <\/code>if<\/code>(args.length != <\/code>1<\/code>)<\/code><\/div>\n
               <\/code>throw<\/code> new<\/code> RuntimeException(<\/code>\"The name of the XML file is required!\"<\/code>);<\/code><\/div>\n
 <\/div>\n
          <\/code>DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();<\/code><\/div>\n
          <\/code>DocumentBuilder builder = factory.newDocumentBuilder();<\/code><\/div>\n
 <\/div>\n
          <\/code>\/\/ Load the input XML document, parse it and return an instance of the<\/code><\/div>\n
          <\/code>\/\/ Document class.<\/code><\/div>\n
          <\/code>Document document = builder.parse(<\/code>new<\/code> File(args[<\/code>0<\/code>]));<\/code><\/div>\n
 <\/div>\n
          <\/code>List<Employee> employees = <\/code>new<\/code> ArrayList<Employee>();<\/code><\/div>\n
          <\/code>NodeList nodeList = document.getDocumentElement().getChildNodes();<\/code><\/div>\n
          <\/code>for<\/code> (<\/code>int<\/code> i = <\/code>0<\/code>; i < nodeList.getLength(); i++) {<\/code><\/div>\n
               <\/code>Node node = nodeList.item(i);<\/code><\/div>\n
 <\/div>\n
               <\/code>if<\/code> (node.getNodeType() == Node.ELEMENT_NODE) {<\/code><\/div>\n
                    <\/code>Element elem = (Element) node;<\/code><\/div>\n
 <\/div>\n
                    <\/code>\/\/ Get the value of the ID attribute.<\/code><\/div>\n
                    <\/code>String ID = node.getAttributes().getNamedItem(<\/code>\"ID\"<\/code>).getNodeValue();<\/code><\/div>\n
 <\/div>\n
                    <\/code>\/\/ Get the value of all sub-elements.<\/code><\/div>\n
                    <\/code>String firstname = elem.getElementsByTagName(<\/code>\"Firstname\"<\/code>)<\/code><\/div>\n
                                        <\/code>.item(<\/code>0<\/code>).getChildNodes().item(<\/code>0<\/code>).getNodeValue();<\/code><\/div>\n
 <\/div>\n
                    <\/code>String lastname = elem.getElementsByTagName(<\/code>\"Lastname\"<\/code>).item(<\/code>0<\/code>)<\/code><\/div>\n
                                        <\/code>.getChildNodes().item(<\/code>0<\/code>).getNodeValue();<\/code><\/div>\n
 <\/div>\n
                    <\/code>Integer age = Integer.parseInt(elem.getElementsByTagName(<\/code>\"Age\"<\/code>)<\/code><\/div>\n
                                        <\/code>.item(<\/code>0<\/code>).getChildNodes().item(<\/code>0<\/code>).getNodeValue());<\/code><\/div>\n
 <\/div>\n
                    <\/code>Double salary = Double.parseDouble(elem.getElementsByTagName(<\/code>\"Salary\"<\/code>)<\/code><\/div>\n
                                        <\/code>.item(<\/code>0<\/code>).getChildNodes().item(<\/code>0<\/code>).getNodeValue());<\/code><\/div>\n
 <\/div>\n
                    <\/code>employees.add(<\/code>new<\/code> Employee(ID, firstname, lastname, age, salary));<\/code><\/div>\n
               <\/code>}<\/code><\/div>\n
          <\/code>}<\/code><\/div>\n
 <\/div>\n
          <\/code>\/\/ Print all employees.<\/code><\/div>\n
          <\/code>for<\/code> (Employee empl : employees)<\/code><\/div>\n
               <\/code>System.out.println(empl.toString());<\/code><\/div>\n
     <\/code>}<\/code><\/div>\n
}<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

Inside the main method, we create a DocumentBuilder<\/a><\/code> from the DocumentBuilderFactory<\/a><\/code> and then, parse and store the XML file in an instance of the Document<\/a><\/code> class. Then, we parse that document and when we find a node of type Node.ELEMENT_NODE<\/a><\/code>, we retrieve all its information and store them in an instance of the Employee class. Finally, we print the information of all stored employees.

<\/div> <\/div><\/p>\n

A sample execution is shown below:<\/p>\n

\n
\n&lt;1, Lebron, James, 30, 2500.0>\n&lt;2, Anthony, Davis, 22, 1500.0>\n&lt;3, Paul, George, 24, 2000.0>\n&lt;4, Blake, Griffin, 25, 2250.0>\n<\/pre>\n<\/div>\n
3. Parse an XML File using the SAX Parser<\/h2>\n
SAX is an event-based sequential access parser API and provides a mechanism for reading data from an XML document that is an alternative to that provided by a DOM parser. A SAX parser only needs to report each parsing event as it happens and the minimum memory required for a SAX parser is proportional to the maximum depth of the XML file.<\/p>\n
Our SAX parser extends the DefaultHandler<\/a><\/code> class, in order to provide the following callbacks:<\/p>\n