How do I get mixed content of an xml element?

The following examples demonstrate how to read mixed content of an xml element. A mixed content can have more than one type of content such as text (Text), comment (Comment), CDATA (CDATA) or some child elements (Element).

You also see that we can remove the mixed content from the element by calling the remove method of the List just like what we do with a collection of data.

package org.kodejava.example.jdom;

import org.jdom.*;
import org.jdom.input.SAXBuilder;

import java.io.IOException;
import java.io.StringReader;
import java.util.List;

public class JDOMMixedContent {
    public static void main(String[] args) {
        String xml = "<root>" +
                "    <data>" +
                "        <!-- This element contains application data -->" +
                "        User Information" +
                "        <![CDATA[<table><tr><td>-data-</td></tr></table>]]>" +
                "        <field name=\"username\">alice</field>" +
                "    </data>" +
                "</root>";

        SAXBuilder builder = new SAXBuilder();
        try {
            Document document = builder.build(new StringReader(xml));
            Element root = document.getRootElement();
            Element data = root.getChild("data");

            // Reading the mixed content of an xml element and iterate
            // the result list. This list object can contains any of the
            // following objects: Comment, Element, CDATA, DocType,
            // ProcessingInstruction, EntityRef and Text.
            List content = data.getContent();

            for (Object o : content) {
                if (o instanceof Comment) {
                    Comment comment = (Comment) o;
                    System.out.println("Comment   = " + comment);
                } else if (o instanceof Element) {
                    Element element = (Element) o;
                    System.out.println("Element   = " + element);
                } else if (o instanceof CDATA) {
                    CDATA cdata = (CDATA) o;
                    System.out.println("CDATA     = " + cdata);
                } else if (o instanceof DocType) {
                    DocType docType = (DocType) o;
                    System.out.println("DocType   = " + docType);
                } else if (o instanceof ProcessingInstruction) {
                    ProcessingInstruction pi = (ProcessingInstruction) o;
                    System.out.println("PI        = " + pi);
                } else if (o instanceof EntityRef) {
                    EntityRef entityRef = (EntityRef) o;
                    System.out.println("EntityRef = " + entityRef);
                } else if (o instanceof Text) {
                    Text text = (Text) o;
                    System.out.println("Text      = " + text);
                }
            }

            // Remove the second mixed content which is the CDATA content.
            content.remove(2);
        } catch (JDOMException | IOException e) {
            e.printStackTrace();
        }
    }
}

Here are the result of our program:

Text      = [Text:         ]
Comment   = [Comment: <!-- This element contains application data -->]
Text      = [Text:         User Information        ]
CDATA     = [CDATA: <table><tr><td>-data-</td></tr></table>]
Text      = [Text:         ]
Element   = [Element: <field/>]
Text      = [Text:     ]

How do I add and remove elements from xml document?

The List returned by the getChildren() method call is a java.util.List. Any modification to the List object immediately reflected in the backing document. This make the manipulation of the XML document easy.

You can also see how we can add a new Element to the document by calling the addContent() method.

package org.kodejava.example.jdom;

import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;
import org.jdom.output.Format;
import org.jdom.output.XMLOutputter;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.List;

public class JDOMAddRemoveElement {
    public static void main(String[] args) {
        String xml = "<root>" +
                "   <user name=\"Alice\" age=\"21\" dob=\"20-01-1988\"/>" +
                "   <user name=\"Bob\" age=\"23\" dob=\"01-05-1986\"/>" +
                "</root>";

        SAXBuilder builder = new SAXBuilder();
        try {
            Document document = builder.build(
                    new ByteArrayInputStream(xml.getBytes()));

            // Adding a new element to the root of the document using the
            // addContent method.
            document.getRootElement().addContent(
                    new Element("people").setAttribute("id", "1"));
            document.getRootElement().addContent(
                    new Element("people").setAttribute("id", "1"));

            // Add a new element. By adding a new element to the List of
            // children we can modified the xml document. Using 
            // java.util.List makes the modification of XML document 
            // simple and easy.
            List<Element> children = document.getRootElement().getChildren();
            children.add(new Element("user")
                    .setAttribute("name", "Carol")
                    .setAttribute("age", "25")
                    .setAttribute("dob", "06-03-1984"));

            // Add element to the beginning of the xml document.
            children.add(0, new Element("user")
                    .setAttribute("name", "Jimmy")
                    .setAttribute("age", "25")
                    .setAttribute("dob", "16-05-1984"));

            // Remove the fourth element.
            children.remove(3);

            XMLOutputter outputter =
                    new XMLOutputter(Format.getPrettyFormat());
            outputter.output(document, System.out);
        } catch (JDOMException | IOException e) {
            e.printStackTrace();
        }
    }
}

The result of this code is:

<?xml version="1.0" encoding="UTF-8"?>
<root>
  <user name="Jimmy" age="25" dob="16-05-1984" />
  <user name="Alice" age="21" dob="20-01-1988" />
  <user name="Bob" age="23" dob="01-05-1986" />
  <people id="1" />
  <user name="Carol" age="25" dob="06-03-1984" />
</root>

How do I navigating the XML elements tree?

package org.kodejava.example.jdom;

import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.text.MessageFormat;
import java.util.List;

public class JDOMTraversingElement {
    public static void main(String[] args) {
        String xml = "<root>" +
                "    <country name=\"Japan\" capital=\"Tokyo\"/>" +
                "    <country name=\"France\" capital=\"Paris\"/>" +
                "    <country name=\"Italy\" capital=\"Rome\"/>" +
                "    <country name=\"England\" capital=\"London\"/>" +
                "    <country name=\"Indonesia\" capital=\"Jakarta\"/>" +
                "    <city name=\"Denpasar\"/>" +
                "    <city name=\"Bangkok\"/>" +
                "    <city name=\"Mumbai\"/>" +
                "    <city name=\"Delhi\"/>" +
                "</root>";

        SAXBuilder builder = new SAXBuilder();
        try {
            Document document = builder.build(
                    new ByteArrayInputStream(xml.getBytes()));

            // Getting the root element
            Element root = document.getRootElement();

            // Getting the first child
            Element country = root.getChild("country");
            System.out.println("Name: " + country.getAttribute("name")
                    .getValue());
            System.out.println("Capital: " + country.getAttribute("capital")
                    .getValue());
            System.out.println("----------------------------------------");

            // Getting all children of the root
            List<Element> elements = root.getChildren();
            for (Element element : elements) {
                if (element.getName().equals("country")) {
                    System.out.println(MessageFormat.format("{0} -> {1}",
                            element.getAttribute("name").getValue(),
                            element.getAttribute("capital").getValue()));
                } else if (element.getName().equals("city")) {
                    System.out.println(element.getAttribute("name")
                            .getValue());
                }
            }
            System.out.println("----------------------------------------");

            // Getting all children of the root named city
            List<Element> cities = root.getChildren("city");
            for (Element city : cities) {
                System.out.println(city.getAttribute("name").getValue());
            }
        } catch (JDOMException | IOException e) {
            e.printStackTrace();
        }
    }
}