Best way to compare 2 XML documents in Java

java

xml-comparison

xml-unit

xml-parsing

byNikita Barsukov·Jan 2, 2025

// Java programmers be like...
// "One does not simply compare two XMLs, one uses XMLUnit for efficient comparisons!" 

import org.xmlunit.builder.DiffBuilder;
import org.xmlunit.diff.Diff;

String expectedXML = "<expected></expected>"; // Our expectations... sadly, they are usually not met!
String actualXML = "<actual></actual>";       // Embrace the brutal reality of life...and code.

Diff myDiff = DiffBuilder.compare(expectedXML).withTest(actualXML).ignoreWhitespace().checkForSimilar().build();

// And now, the moment you've been waiting for! Drumroll, please! 🥁
System.out.println(myDiff.hasDifferences() ? "**Differences Found! FATALITY!**" : "**All quiet on the western front! XMLs Match**");

In the immortal words of Sun Tzu (if he were a programmer): "Know your XMLs, number your diffs, and you shall not fear the result of a thousand commits." The DiffBuilder in XMLUnit enables this wisdom to be embodied in your code.

Deep Dive into XML Comparisons

XML comparison is more than just comparing strings - it's about understanding the structure and syntax of your XML. This is where XMLUnit's assertXMLEqual method shines.

Dealing with Namespaces and Attribute Orders

XML namespaces and attribute orders can give you a headache, that's why XMLUnit's ignoreAttributeOrder is your powerful ally in this battle.

Smooth Integration with Maven

Having the ability to automatically compare your XMLs during the build process can be a godsend. Just update your pom.xml and XMLUnit will weave into your project like a charm.

A Knight in Shining Armor: Xerces or JDOM

When you encounter obstacles with common parsers, do not despair. Xerces and JDOM are here to rescue you, providing unique features and better handling of some rare cases.

Additional Tools and Techniques

Get more from your XML comparison quest with Xom's Canonicalizer, especially for visual warriors - some IDEs like Eclipse offer visual string comparators for a side-by-side duel.