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Java Convert String to XML Document and XML Document to String

Published on August 3, 2022
Java Convert String to XML Document and XML Document to String

Sometimes while programming in java, we get String which is actually an XML and to process it, we need to convert it to XML Document (org.w3c.dom.Document). Also for debugging purpose or to send to some other function, we might need to convert Document object to String. Here I am providing two utility functions.

  1. Document convertStringToDocument(String xmlStr): This method will take input as String and then convert it to DOM Document and return it. We will use InputSource and StringReader for this conversion.
  2. String convertDocumentToString(Document doc): This method will take input as Document and convert it to String. We will use Transformer, StringWriter and StreamResult for this purpose.
package com.journaldev.xml;

import java.io.StringReader;
import java.io.StringWriter;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;
import org.xml.sax.InputSource;

public class StringToDocumentToString {

    public static void main(String[] args) {
        final String xmlStr = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>\n"+
                                "<Emp id=\"1\"><name>Pankaj</name><age>25</age>\n"+
                                "<role>Developer</role><gen>Male</gen></Emp>";
        Document doc = convertStringToDocument(xmlStr);
        
        String str = convertDocumentToString(doc);
        System.out.println(str);
    }

    private static String convertDocumentToString(Document doc) {
        TransformerFactory tf = TransformerFactory.newInstance();
        Transformer transformer;
        try {
            transformer = tf.newTransformer();
            // below code to remove XML declaration
            // transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
            StringWriter writer = new StringWriter();
            transformer.transform(new DOMSource(doc), new StreamResult(writer));
            String output = writer.getBuffer().toString();
            return output;
        } catch (TransformerException e) {
            e.printStackTrace();
        }
        
        return null;
    }

    private static Document convertStringToDocument(String xmlStr) {
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();  
        DocumentBuilder builder;  
        try  
        {  
            builder = factory.newDocumentBuilder();  
            Document doc = builder.parse( new InputSource( new StringReader( xmlStr ) ) ); 
            return doc;
        } catch (Exception e) {  
            e.printStackTrace();  
        } 
        return null;
    }

}

When we run above program, we get the same String output that we used to create DOM Document.

<?xml version="1.0" encoding="UTF-8"?><Emp id="1"><name>Pankaj</name><age>25</age>
<role>Developer</role><gen>Male</gen></Emp>

You can use replaceAll("\n|\r", "") to remove new line characters from String and get it in compact format.

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About the author

Pankaj Kumar
Pankaj Kumar
Author
See author profile

Java and Python Developer for 20+ years, Open Source Enthusiast, Founder of https://www.askpython.com/, https://www.linuxfordevices.com/, and JournalDev.com (acquired by DigitalOcean). Passionate about writing technical articles and sharing knowledge with others. Love Java, Python, Unix and related technologies. Follow my X @PankajWebDev

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Was this helpful?

I m using same code but stringwriter truncates before printing entire xml in to string…if u can help why it is happening?

- Rishi Naik

I need to convert XML String to XML SAX document…how can that be done?

- simran

Hi, this line Document doc = builder.parse( new InputSource( new StringReader( xmlStr ) ) ); Gives me an error when i’m running… Fatal Error: XML document structures must start and end within the same entity. My xmlStr = " 1 2 3 "; There is something I’m not doing right? Thank you for you help and article!

- German

Thanks Pankaj you r a lifesaver

- Deepu

Hi, Am using the above code example but getting null value returning in document

- ragu

Getting below error for DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); Exception in thread “main” javax.xml.parsers.FactoryConfigurationError: Provider for class javax.xml.parsers.DocumentBuilderFactory cannot be created at javax.xml.parsers.FactoryFinder.findServiceProvider(Unknown Source) at javax.xml.parsers.FactoryFinder.find(Unknown Source) at javax.xml.parsers.DocumentBuilderFactory.newInstance(Unknown Source)

- RInu

Getting the null from builder.parse( new InputSource( new StringReader( xmlStr ) ) ); … I validated my xml, it’s valid

- Anuj

successfully executed but did not found useful. I want convert doc file into xml

- ahmad

The variable doc allways return null

- mmonikm

Where is the replaceAll() method supposed to be used? I was thinking it should be placed on the string str before printing it out, like so: String str = convertDocumentToString(doc); str.replaceAll(“\n|\r”, “”); System.out.println(str); But the output doesn’t change…

- nekonutchi

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