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Ilias Tsagklis
Ilias is a software developer turned online entrepreneur. He is co-founder and Executive Editor at Java Code Geeks.

Pretty print XML in Java

This is an example of how to pretty print an xml file in Java. We have implemented a method, that is void prettyPrint(Document xml), in order to transform the DOM Document to a formatted xml String. The steps to get an xml file and pretty print it in a String format using the example’s method is described below:

  • Obtain a new instance of a DocumentBuilderFactory, that is a factory API that enables applications to obtain a parser that produces DOM object trees from XML documents.
  • Set the parser produced so as not to validate documents as they are parsed, using setValidating(boolean validating) API method of DocumentBuilderFactory, with validating set to false.
  • Create a new instance of a DocumentBuilder, using newDocumentBuilder() API method of DocumentBuilderFactory.
  • Parse the FileInputStream with the content to be parsed, using parse(InputStream is) API method of DocumentBuilder. This method parses the content of the given InputStream as an XML document and returns a new DOM Document object.
  • Call void prettyPrint(Document xml) method of the example. The method gets the xml Document and prints it after transforming it with specific parameters, such as encoding. The method uses a Transformer, that is created using newTransformer() API method of TransformerFactory. The Transformer is used to transform a source tree into a result tree. After setting specific output properties to the transformer, using setOutputProperty(String name, String value) API method of Transformer, the method uses it to make the transformation, with transform(Source xmlSource, Result outputTarget) API method of Transformer. The parameters are the DOMSource with the DOM node and the result that is a StreamResult created from a StringWriter.

Let’s take a look at the code snippet that follows:  

package com.javacodegeeks.snippets.core;

import java.io.File;
import java.io.FileInputStream;
import java.io.StringWriter;
import java.io.Writer;

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

import org.w3c.dom.Document;

public class PrettyPrintXMLInJava {
	
	public static void main(String[] args) throws Exception {
		
		DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
		dbf.setValidating(false);
		DocumentBuilder db = dbf.newDocumentBuilder();
		
		Document doc = db.parse(new FileInputStream(new File("in.xml")));
		prettyPrint(doc);
		
	}
	
	public static final void prettyPrint(Document xml) throws Exception {
		Transformer tf = TransformerFactory.newInstance().newTransformer();
		tf.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
		tf.setOutputProperty(OutputKeys.INDENT, "yes");
		Writer out = new StringWriter();
		tf.transform(new DOMSource(xml), new StreamResult(out));
		System.out.println(out.toString());
	}

}

Input:

<?xml version="1.0" encoding="UTF-8"?><rss version="2.0"><channel><title>Java Tutorials and Examples 1</title><language>en-us</language></channel></rss>

Output:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<rss version="2.0">
<channel>
<title>Java Tutorials and Examples 1</title>
<language>en-us</language>
</channel>
</rss>

  
This was an example of how to pretty print an xml file in Java.

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2 Comments
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Sumit
Sumit
1 year ago

it was not working for me for a big XML(942 lines) file…

ashu
ashu
2 months ago

I am getting error as below.

Exception in thread “main” java.io.FileNotFoundException: NewFile.xml (The system cannot find the file specified)
at java.io.FileInputStream.open0(Native Method)
at java.io.FileInputStream.open(Unknown Source)
at java.io.FileInputStream.(Unknown Source)
at PrettyPrintXMLInJava.main(PrettyPrintXMLInJava.java:24)