How to append xml file in java

Question

I've been using xml files to save data from my java program. I'm using the java DOM api. I want to add to the document by adding an element and then adding children to that element. I tried doing it using this code but when i run it it does nothing. Is there another way of doing it that would be simple and work better? is there a way i can get this code working?

File file = new File("C:/users/peter/desktop/newxml.xml");
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    DocumentBuilder db = dbf.newDocumentBuilder();
    Document document = db.parse(file);
    Element newB = document.createElement("B");
    Element newC = document.createElement("c");
    newC.setTextContent("11");
    Element newD = document.createElement("d");
    newD.setTextContent("21");
    Element newE = document.createElement("e");
    newE.setTextContent("31");
    newB.appendChild(newC);
    newB.appendChild(newD);
    newB.appendChild(newE);
    document.getDocumentElement().appendChild(newB);

Briefly - the reason that it "does nothing" is that your code is not writing out the DOM once you've made the changes to the in-memory data structure. — Stephen C
– Stephen C, Commented Mar 3, 2011 at 3:43
You can write out a dom, by using a Transformer with a null transform (stylesheet) and the destination being a StreamResult. — MeBigFatGuy
– MeBigFatGuy, Commented Mar 3, 2011 at 4:29

marc_s · Accepted Answer · 2016-05-09 05:24:37Z

This java code works to append new node to the xml file......it is based on DOM

import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import java.io.FileOutputStream;
public class writexml1 {

public static void main (String args[]) 
{

File docFile = new File("..\\jquery\\WebContent\\demo\\testing.xml");

Document doc = null;
try 
{
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
doc = db.parse(docFile);
} 
catch (java.io.IOException e) 
{
System.out.println("Can't find the file");
} 
catch (Exception e) 
{
System.out.print("Problem parsing the file.");
}

Element root = doc.getDocumentElement();

System.out.println("The root element is " + root.getNodeName() + ".\n");

NodeList children = root.getChildNodes();
System.out.print("There are "+children.getLength()+" child elements.\n");
System.out.print("They are: \n");

//Print the file 
for (Node child = root.getFirstChild();child != null;child = child.getNextSibling())
{
if (child.getNodeType() == child.TEXT_NODE)
{
System.out.println("Text: "+child.getNodeValue());
} 
else if (child.getNodeType() == child.ELEMENT_NODE) 
{
System.out.println(child.getNodeName()+" = "+child.getFirstChild().getNodeValue());
}
}


//NodeList deleteElement = root.getElementsByTagName("staff");

//Node deleteNode= deleteElement.item(0);

//root.removeChild(deleteNode); 
Element staffElement = doc.createElement("staff");

Node updateText = doc.createTextNode("");
staffElement.appendChild(updateText);
//
Element firstName = doc.createElement("firstname");
String str_firstName="added firstname";
Node firstNameNode = doc.createTextNode(str_firstName);
firstName.appendChild(firstNameNode);

staffElement.appendChild(firstName);

//

Element lastName = doc.createElement("lastname");
String str_lastName="added lastname";
Node lastNameNode = doc.createTextNode(str_lastName);
lastName.appendChild(lastNameNode);

staffElement.appendChild(lastName);


//
Element nickName = doc.createElement("nickname");
String str_nickName="added nickname";
Node nickNameNode = doc.createTextNode(str_nickName);
nickName.appendChild(nickNameNode);

staffElement.appendChild(nickName);


//
Element salary = doc.createElement("salary");
String str_salary="$10,000";
Node salaryNode = doc.createTextNode(str_salary);
salary.appendChild(salaryNode);

staffElement.appendChild(salary);


//
root.appendChild(staffElement);

//Node StaffNode=(Node)updateElement;





try{
String outputURL = "..\\jquery\\WebContent\\demo\\testing.xml";

DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(new FileOutputStream(outputURL));

TransformerFactory transFactory = TransformerFactory.newInstance();
Transformer transformer = transFactory.newTransformer();

transformer.transform(source, result);

} catch (Exception e) {
e.printStackTrace();
}

}

}

Kevin · Accepted Answer · 2011-03-03 03:10:29Z

you should check out the JAXB API. If I understand right, you're xml looks like this:

<B>
    <C>11</C>
    <D>21</D>
    <E>31</E>
</B>

So code would be:

import javax.xml.bind.JAXBContext;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAccessType;

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class B {
    @XmlElement public String C; // sloppy, probably should be type Integer or something
    @XmlElement public String D;
    @XmlElement public String E;
}

// then, somewhere else in your code you want to serialize...
B b = new B();
b.C = "11";
b.D = "21";
b.E = "31";

JAXBContext c = JAXBContext.newInstance(B.class);

// where w is a Writer instance
c.createMarshaller().marshal(b, w);

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