How To Compare DOCX Documents in Java

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Introduction to DOCX Document Comparison

Comparing DOCX documents programmatically can be essential for various applications, such as detecting plagiarism, version control, or ensuring consistency across documents. Java, being a versatile and powerful programming language, offers several libraries to facilitate this process. In this article, we’ll explore how to compare DOCX documents using Java, with detailed coding examples and step-by-step instructions. We will cover libraries like Apache POI, docx4j, and JavaDiffUtils to demonstrate different approaches for document comparison.

DOCX is a widely used format for text documents, primarily used by Microsoft Word. Comparing DOCX documents involves examining the content and structure to identify differences. This can include text changes, formatting differences, and more. Java provides libraries that can read, manipulate, and compare these documents efficiently.

Prerequisites

Before diving into the code, ensure you have the following prerequisites:

  1. Java Development Kit (JDK): Ensure you have JDK 8 or higher installed.
  2. Maven: We’ll use Maven to manage dependencies.
  3. Integrated Development Environment (IDE): IntelliJ IDEA, Eclipse, or any IDE of your choice.

Setting Up the Project

We’ll use Maven for dependency management. Create a new Maven project and add the following dependencies in your pom.xml file:

xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.example</groupId>
<artifactId>docx-comparator</artifactId>
<version>1.0-SNAPSHOT</version><dependencies>
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>5.0.0</version>
</dependency>
<dependency>
<groupId>org.docx4j</groupId>
<artifactId>docx4j</artifactId>
<version>8.3.3</version>
</dependency>
<dependency>
<groupId>org.bitbucket.cowwoc</groupId>
<artifactId>diff-match-patch</artifactId>
<version>1.1</version>
</dependency>
</dependencies>
</project>

Comparing DOCX Documents with Apache POI

Apache POI is a popular library for handling Microsoft Office files. We’ll start by comparing the textual content of two DOCX files using Apache POI.

Reading DOCX Files

First, let’s write a method to read the text content from a DOCX file using Apache POI:

java

import org.apache.poi.xwpf.usermodel.XWPFDocument;
import org.apache.poi.xwpf.usermodel.XWPFParagraph;import java.io.FileInputStream;
import java.io.IOException;
import java.util.List;public class DocxComparator {public static String readDocxFile(String filePath) throws IOException {
FileInputStream fis = new FileInputStream(filePath);
XWPFDocument document = new XWPFDocument(fis);
StringBuilder content = new StringBuilder();List<XWPFParagraph> paragraphs = document.getParagraphs();
for (XWPFParagraph paragraph : paragraphs) {
content.append(paragraph.getText()).append(“\n”);
}fis.close();
return content.toString();
}

public static void main(String[] args) {
try {
String content1 = readDocxFile(“file1.docx”);
String content2 = readDocxFile(“file2.docx”);

// Print content for verification
System.out.println(“Content of File 1:\n” + content1);
System.out.println(“Content of File 2:\n” + content2);
} catch (IOException e) {
e.printStackTrace();
}
}
}

Comparing Textual Content

Next, we will compare the text content of the two DOCX files. We can use a simple string comparison for this purpose:

java

public static void compareTextContent(String content1, String content2) {
if (content1.equals(content2)) {
System.out.println("The documents are identical.");
} else {
System.out.println("The documents have differences.");
}
}public static void main(String[] args) {
try {
String content1 = readDocxFile(“file1.docx”);
String content2 = readDocxFile(“file2.docx”);compareTextContent(content1, content2);
} catch (IOException e) {
e.printStackTrace();
}
}

This approach provides a basic comparison by checking if the text content of both documents is identical. However, it does not highlight the specific differences.

Highlighting Differences with JavaDiffUtils

To highlight specific differences between the text content of two DOCX files, we can use the JavaDiffUtils library. This library provides a diff algorithm to find differences between sequences of text.

Using JavaDiffUtils

First, add the JavaDiffUtils dependency in your pom.xml file:

xml

<dependency>
<groupId>org.bitbucket.cowwoc</groupId>
<artifactId>diff-match-patch</artifactId>
<version>1.1</version>
</dependency>

Next, write a method to highlight differences:

java

import name.fraser.neil.plaintext.diff_match_patch;
import java.util.LinkedList;public static void highlightDifferences(String content1, String content2) {
diff_match_patch dmp = new diff_match_patch();
LinkedList<diff_match_patch.Diff> diffs = dmp.diff_main(content1, content2);
dmp.diff_cleanupSemantic(diffs);for (diff_match_patch.Diff diff : diffs) {
switch (diff.operation) {
case INSERT:
System.out.print(“[+]” + diff.text);
break;
case DELETE:
System.out.print(“[-]” + diff.text);
break;
case EQUAL:
System.out.print(diff.text);
break;
}
}
}public static void main(String[] args) {
try {
String content1 = readDocxFile(“file1.docx”);
String content2 = readDocxFile(“file2.docx”);highlightDifferences(content1, content2);
} catch (IOException e) {
e.printStackTrace();
}
}

This method uses the diff_match_patch library to find and highlight differences between the two documents. Insertions are marked with [+] and deletions with [-].

Comparing DOCX Documents with docx4j

docx4j is another powerful library for manipulating DOCX files in Java. It provides more advanced features for document comparison, including the ability to compare document structures and formatting.

Setting Up docx4j

Add the docx4j dependency to your pom.xml file:

xml

<dependency>
<groupId>org.docx4j</groupId>
<artifactId>docx4j</artifactId>
<version>8.3.3</version>
</dependency>

Comparing DOCX Documents

Let’s use docx4j to compare two DOCX documents. We will compare both the text content and the formatting:

java

import org.docx4j.openpackaging.packages.WordprocessingMLPackage;
import org.docx4j.openpackaging.parts.WordprocessingML.MainDocumentPart;public class DocxComparator {public static void compareDocxFiles(String filePath1, String filePath2) throws Exception {
WordprocessingMLPackage wordMLPackage1 = WordprocessingMLPackage.load(new File(filePath1));
WordprocessingMLPackage wordMLPackage2 = WordprocessingMLPackage.load(new File(filePath2));MainDocumentPart documentPart1 = wordMLPackage1.getMainDocumentPart();
MainDocumentPart documentPart2 = wordMLPackage2.getMainDocumentPart();String text1 = documentPart1.getXML();
String text2 = documentPart2.getXML();// Compare the XML content of both documents
if (text1.equals(text2)) {
System.out.println(“The documents are identical.”);
} else {
System.out.println(“The documents have differences.”);
}
}

public static void main(String[] args) {
try {
compareDocxFiles(“file1.docx”, “file2.docx”);
} catch (Exception e) {
e.printStackTrace();
}
}
}

This approach compares the XML content of the DOCX files, which includes both the text and formatting.

Conclusion

In this article, we explored different methods for comparing DOCX documents in Java. We started with Apache POI for basic text extraction and comparison, then used JavaDiffUtils to highlight specific text differences, and finally leveraged docx4j for a more comprehensive comparison that includes document structure and formatting.

Each method has its own use case:

  1. Apache POI: Suitable for simple text comparisons.
  2. JavaDiffUtils: Ideal for highlighting specific text differences.
  3. docx4j: Best for comprehensive comparisons, including formatting and structure.

By choosing the right tool for your specific needs, you can efficiently compare DOCX documents in Java, ensuring accuracy and consistency in your applications. Whether you are developing a plagiarism detection tool, a version control system, or any other application requiring document comparison, these methods will provide a solid foundation to build upon.