Java: Compare PDF Documents

Comparison of PDF documents is essential for effective document management. By comparing PDF documents, users can easily identify differences in document content to have a more comprehensive understanding of them, which will greatly facilitate the user to modify and integrate the document content. This article will introduce how to use Spire.PDF for Java to compare PDF documents and find the differences.

• Compare Two PDF Documents
• Compare a Specified Page Range of Two PDF Documents

Examples of the two PDF documents that will be used for comparison:

Install Spire.PDF for Java

First of all, you need to add the Spire.Pdf.jar file as a dependency in your Java program. The JAR file can be downloaded from this link. If you use Maven, you can easily import the JAR file by adding the following code to your project's pom.xml file.

<repositories>
    <repository>
        <id>com.e-iceblue</id>
        <name>e-iceblue</name>
        <url>https://repo.e-iceblue.com/nexus/content/groups/public/</url>
    </repository>
</repositories>
<dependencies>
    <dependency>
        <groupId>e-iceblue</groupId>
        <artifactId>spire.pdf</artifactId>
        <version>10.4.4</version>
    </dependency>
</dependencies>
    

Compare Two PDF Documents

Spire.PDF for Java provides the PdfComparer class for users to create an object with two PDF documents for comparing. After creating the PdfComparer object, users can use PdfComparer.compare(String fileName) method to compare the two documents and save the result as a new PDF file.

The resulting PDF document displays the two original documents on the left and the right, with the deleted items in red and the added items in yellow.

The detailed steps for comparing two PDF documents are as follows:

• Create two objects of PdfDocument class and load two PDF documents using PdfDocument.loadFromFile() method.
• Create an object of PdfComparer class with the two documents.
• Compare the two documents and save the result as a new PDF document using PdfComparer.compare() method.

import com.spire.pdf.PdfDocument;
import com.spire.pdf.comparison.PdfComparer;

public class ComparePDFPageRange {
    public static void main(String[] args) {
        //Create an object of PdfDocument class and load a PDF document
        PdfDocument pdf1 = new PdfDocument();
        pdf1.loadFromFile("Sample1.pdf");

        //Create another object of PdfDocument class and load another PDF document
        PdfDocument pdf2 = new PdfDocument();
        pdf2.loadFromFile("Sample2.pdf");

        //Create an object of PdfComparer class
        PdfComparer comparer = new PdfComparer(pdf1,pdf2);

        //Compare the two PDF documents and save the compare results to a new document
        comparer.compare("ComparisonResult.pdf");
    }
}

Compare a Specified Page Range of Two PDF Documents

Before comparing, users can use the PdfComparer.getOptions().setPageRanges() method to limit the page range to be compared. The detailed steps are as follows:

• Create two objects of PdfDocument class and load two PDF documents using PdfDocument.loadFromFile() method.
• Create an object of PdfComparer class with the two documents.
• Set the page range to be compared using PdfComparer.getOptions().setPageRanges() method.
• Compare the two documents and save the result as a new PDF document using PdfComparer.compare() method.

import com.spire.pdf.PdfDocument;
import com.spire.pdf.comparison.PdfComparer;

public class ComparePDFPageRange {
    public static void main(String[] args) {
        //Create an object of PdfDocument class and load a PDF document
        PdfDocument pdf1 = new PdfDocument();
        pdf1.loadFromFile("G:/Documents/Sample6.pdf");

        //Create another object of PdfDocument class and load another PDF document
        PdfDocument pdf2 = new PdfDocument();
        pdf2.loadFromFile("G:/Documents/Sample7.pdf");

        //Create an object of PdfComparer class
        PdfComparer comparer = new PdfComparer(pdf1,pdf2);

        //Set the page range to be compared
        comparer.getOptions().setPageRanges(1, 1, 1, 1);

        //Compare the two PDF documents and save the compare results to a new document
        comparer.compare("ComparisonResult.pdf");
    }
}

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