Modify or Edit PDF Files in Java: Practical Code Examples Included

Edit PDF Documents in Java

Working with PDF files is a common requirement in many Java applications—whether you’re generating invoices, modifying contracts, or adding annotations to reports. While the PDF format is reliable for sharing documents, editing it programmatically can be tricky without the right library.

In this tutorial, you’ll learn how to add, replace, remove, and secure content in a PDF file using Spire.PDF for Java , a comprehensive and developer-friendly PDF API. We’ll walk through examples of adding pages, text, images, tables, annotations, replacing content, deleting elements, and securing files with watermarks and passwords.

Table of Contents:

Why Use Spire.PDF to Edit PDF in Java
Setting Up Your Java Environment
Adding Content to a PDF File
Replacing Content in a PDF File
Removing Content from a PDF File
Securing Your PDF File
Conclusion
FAQs About Editing PDF in Java

Why Use Spire.PDF to Edit PDF in Java

Spire.PDF offers a comprehensive set of features that make it an excellent choice for developers looking to work with PDF files in Java. Here are some reasons why you should consider using Spire.PDF:

Ease of Use : The API is straightforward and intuitive, allowing you to perform complex operations with minimal code.
Rich Features : Spire.PDF supports a wide range of functionalities, including text and image manipulation, page management, and security features.
High Performance : The library is optimized for performance, ensuring that even large PDF files can be processed quickly.
No Dependencies : Spire.PDF is a standalone library, meaning you won’t have to include any additional dependencies in your project.

By leveraging Spire.PDF, you can easily handle PDF files without getting bogged down in the complexities of the format itself.

Setting Up Your Java Environment

Installation

To begin using Spire.PDF, you'll first need to add it to your project. You can download the library from its official website or include it via Maven:

For Maven users:

<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>11.9.6</version>
    </dependency>
</dependencies>

For manual setup:

Download Spire.PDF for Java from the official website and add the JAR file to your project’s classpath.

Initiate Document Loading

Once you have the library set up, you can start loading PDF documents. Here’s how to do it:

PdfDocument doc = new PdfDocument();
doc.loadFromFile("C:\\Users\\Administrator\\Desktop\\sample.pdf");

This snippet initializes a new PdfDocument object and loads a PDF file from the specified path. By calling loadFromFile , you prepare the document for further editing.

Adding Content to a PDF File in Java

Add a New Page

Adding a new page to an existing PDF document is quite simple. Here’s how you can do it:

// Add a new page
PdfPageBase new_page = doc.getPages().add(PdfPageSize.A4, new PdfMargins(54));
// Draw text or do other operations on the page
new_page.getCanvas().drawString("This is a Newly-Added Page.", new PdfTrueTypeFont(new Font("Times New Roman",Font.PLAIN,18)), PdfBrushes.getBlue(), 0, 0);

In this code, we create a new page with A4 size and specified margins using the add method. We then draw a string on the new page using a specified font and color. The drawString method places the text at the top-left corner of the page, allowing you to add content quickly.

Add Text to a PDF File

To insert text into a specific area of an existing page, use the following code:

// Get a specific page
PdfPageBase page = doc.getPages().get(0);
// Define a rectangle for placing the text
Rectangle2D.Float rect = new Rectangle2D.Float(54, 300, (float) page.getActualSize().getWidth() - 108, 100);
// Create a brush and a font
PdfSolidBrush brush = new PdfSolidBrush(new PdfRGBColor(Color.BLUE));
PdfTrueTypeFont font = new PdfTrueTypeFont(new Font("Times New Roman",Font.PLAIN,18));
// Draw text on the page at the specified area
page.getCanvas().drawString("This Line is Created By Spire.PDF for Java.",font, brush, rect);

This snippet retrieves the first page of the document and defines a rectangle where the text will be placed. The Rectangle2D.Float class allows you to specify the exact dimensions for positioning the text. We then draw the specified text with a blue brush and custom font using the drawString method, which ensures that the text is rendered in the defined area.

Add Text to PDF in Java

Add an Image to a PDF File

Inserting images into a PDF is straightforward as well:

// Get a specific page
PdfPageBase page = doc.getPages().get(0);
// Load an image
PdfImage image = PdfImage.fromFile("C:\\Users\\Administrator\\Desktop\\logo.png");
// Specify coordinates for adding image
float x = 54;
float y = 300;
// Draw image on the page at the specified coordinates
page.getCanvas().drawImage(image, x, y);

Here, we load an image from a specified file path and draw it on the first page at the defined coordinates (x, y). The drawImage method allows you to position the image precisely, making it easy to incorporate visuals into your document.

Add Image to PDF in Java

Add a Table to a PDF File

Adding tables is also supported in Spire.PDF:

// Get a specific page
PdfPageBase page = doc.getPages().get(0);
// Create a table
PdfTable table = new PdfTable();
// Define table data
String[][] data = {
        new String[]{"Name", "Age", "Country"},
        new String[]{"Alice", "25", "USA"},
        new String[]{"Bob", "30", "UK"},
        new String[]{"Charlie", "28", "Canada"}
};
// Assign data to the table
table.setDataSource(data);
// Set table style
PdfTableStyle style = new PdfTableStyle();
style.getDefaultStyle().setFont(new PdfTrueTypeFont(new Font("Arial", Font.PLAIN, 12)));
table.setStyle(style);
// Draw the table on the page
table.draw(page, new Point2D.Float(50, 80));

In this example, we create a table and define its data source using a 2D array. After assigning the data, we set a style for the table using PdfTableStyle , which allows you to customize the font and appearance of the table. Finally, we use the draw method to render the table on the first page at the specified coordinates.

Add an Annotation or Comment

Annotations can enhance the interactivity of PDFs:

// Get a specific page
PdfPageBase page = doc.getPages().get(0);
// Create a free text annotation
PdfPopupAnnotation popupAnnotation = new PdfPopupAnnotation();
popupAnnotation.setLocation(new Point2D.Double(90, 260));
// Set the content of the annotation
popupAnnotation.setText("Here is a popup annotation added by Spire.PDF for Java.");
// Set the icon and color of the annotation
popupAnnotation.setIcon(PdfPopupIcon.Comment);
popupAnnotation.setColor(new PdfRGBColor(Color.RED));
// Add the annotation to the collection of the annotations
page.getAnnotations().add(popupAnnotation);

This snippet creates a popup annotation at a specified location on the page. By calling setLocation , you definewhere the annotation appears. The setText method allows you to specify the content displayed in the annotation, while you can set the icon and color to customize its appearance. Finally, the annotation is added to the page's collection of annotations.

Add Image to PDF in Java

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Replacing Content in a PDF File in Java

Replace Text in a PDF File

To replace existing text within a PDF, you can use the following code:

// Create a PdfTextReplaceOptions object
PdfTextReplaceOptions textReplaceOptions = new PdfTextReplaceOptions();
// Specify the options for text replacement
textReplaceOptions.setReplaceType(EnumSet.of(ReplaceActionType.IgnoreCase));
// Iterate through the pages
for (int i = 0; i < doc.getPages().getCount(); i++) {

// Get a specific page
PdfPageBase page = doc.getPages().get(i);
// Create a PdfTextReplacer object based on the page
PdfTextReplacer textReplacer = new PdfTextReplacer(page);
// Set the replace options
textReplacer.setOptions(textReplaceOptions);
// Replace all occurrences of target text with new text
textReplacer.replaceAllText("Water", "H₂O");
}

In this example, we create a PdfTextReplaceOptions object to specify replacement options, such as ignoring case sensitivity. We then iterate through all pages of the document, creating a PdfTextReplacer for each page. The replaceAllText method is called on the text replacer to replace all occurrences of "Water" with "H₂O".

Replace Text in PDF in Java

Replace an Image in a PDF File

Replacing an image follows a similar pattern:

// Get a specific page
PdfPageBase page = doc.getPages().get(0);
// Load an image
PdfImage image = PdfImage.fromFile("C:\\Users\\Administrator\\Desktop\\logo.png");
// Get the image information from the page
PdfImageHelper imageHelper = new PdfImageHelper();
PdfImageInfo[] imageInfo = imageHelper.getImagesInfo(page);
// Replace Image
imageHelper.replaceImage(imageInfo[0], image);

This code retrieves the image information from the specified page using the PdfImageHelper class. After loading a new image from a file, we call replaceImage to replace the first image found on the page with the new one.

Replace Image in PDF in Java

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Removing Content from a PDF File in Java

Remove a Page from a PDF File

To remove an entire page from a PDF, use the following code:

// Remove a specific page
doc.getPages().removeAt(0);

This straightforward command removes the first page from the document. By calling removeAt , you specify the index of the page to be removed, simplifying page management in your PDF.

Delete an Image from a PDF File

To remove an image from a page:

// Get a specific page
PdfPageBase page = pdf.getPages().get(0);
// Get the image information from the page
PdfImageHelper imageHelper = new PdfImageHelper();
PdfImageInfo[] imageInfos = imageHelper.getImagesInfo(page);
// Delete the specified image on the page
imageHelper.deleteImage(imageInfos[0]);

This code retrieves all images from the first page and deletes the first image using the deleteImage method from PdfImageHelper .

Delete an Annotation

Removing an annotation is simple as well:

// Get a specific page
PdfPageBase page = pdf.getPages().get(0);
// Remove the specified annotation
page.getAnnotationsWidget().removeAt(0);

This snippet removes the first annotation from the specified page. The removeAt method is used to specify which annotation to remove, ensuring that the document can be kept clean and free of unnecessary comments.

Delete an Attachment

To delete an attachment from a PDF:

// Get the attachments collection
PdfAttachmentCollection attachments = doc.getAttachments();
// Remove a specific attachment
attachments.removeAt(0);

This code retrieves the collection of attachments from the document and removes the first one using the removeAt method.

Securing Your PDF File in Java

Apply a Watermark to a PDF File

Watermarks can be added for branding or copyright purposes:

// Create a font and a brush
PdfTrueTypeFont font = new PdfTrueTypeFont(new Font("Arial Black", Font.PLAIN, 50), true);
PdfBrush brush = PdfBrushes.getBlue();
// Specify the watermark text
String watermarkText = "DO NOT COPY";
// Specify the opacity level
float opacity = 0.6f;
// Iterate through the pages
for (int i = 0; i < doc.getPages().getCount(); i++) {
    PdfPageBase page = doc.getPages().get(i);    
    // Set the transparency level for the watermark
    page.getCanvas().setTransparency(opacity);
    // Measure the size of the watermark text
    Dimension2D textSize = font.measureString(watermarkText);
    // Get the width and height of the page
    double pageWidth = page.getActualSize().getWidth();
    double pageHeight = page.getActualSize().getHeight();
    // Calculate the position to center the watermark on the page
    double x = (pageWidth - textSize.getWidth()) / 2;
    double y = (pageHeight - textSize.getHeight()) / 2;
    // Draw the watermark text on the page at the calculated position
    page.getCanvas().drawString(watermarkText, font, brush, x, y);
}

This code configures the appearance of a text watermark and places it at the center of each page in a PDF file using the drawString method, effectively discouraging unauthorized copying.

Password Protect a PDF File

To secure your PDF with a password:

// Specify the user and owner passwords
String userPassword = "open_psd";
String ownerPassword = "permission_psd";
// Create a PdfSecurityPolicy object with the two passwords
PdfSecurityPolicy securityPolicy = new PdfPasswordSecurityPolicy(userPassword, ownerPassword);
// Set encryption algorithm
securityPolicy.setEncryptionAlgorithm(PdfEncryptionAlgorithm.AES_256);
// Set document permissions (If you do not set, the default is Forbid All)
securityPolicy.setDocumentPrivilege(PdfDocumentPrivilege.getAllowAll());
// Restrict editing
securityPolicy.getDocumentPrivilege().setAllowModifyContents(false);
securityPolicy.getDocumentPrivilege().setAllowCopyContentAccessibility(false);
securityPolicy.getDocumentPrivilege().setAllowContentCopying(false);
// Encrypt the PDF file
doc.encrypt(securityPolicy);

This code applies password protection and encryption to a PDF document by defining a user password (for opening) and an owner password (for permissions like editing and printing). The PdfSecurityPolicy object manages security settings, including the AES-256 encryption algorithm and permission levels. Finally, doc.encrypt(securityPolicy) encrypts the document, ensuring only authorized users can access or modify it.

Protect PDF in Java

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Conclusion

Editing PDF files in Java is often seen as challenging, but with Spire.PDF for Java, it becomes a straightforward and efficient process. This library provides developers with the flexibility to create, modify, replace, and secure PDF content using clean, easy-to-understand APIs. From adding pages and images to encrypting sensitive documents, Spire.PDF simplifies every step of the workflow while maintaining professional output quality.

Beyond basic editing, Spire.PDF’s capabilities extend to automation and enterprise-level solutions. Whether you’re integrating PDF manipulation into a document management system, or generating customized reports, the library offers a stable and scalable foundation for long-term projects. With its comprehensive feature set and strong performance, Spire.PDF for Java is a reliable choice for developers seeking precision, efficiency, and control over PDF documents.

FAQs About Editing PDF in Java

Q1. What is the best library for editing PDFs in Java?

Spire.PDF for Java is a popular choice among developers worldwide, which provides comprehensive range of features for effective PDF manipulation.

Q2. Can I edit existing text in a PDF using Java?

With Spire.PDF for Java, you can replace or modify existing text using classes like PdfTextReplacer along with customizable options for case sensitivity and matching behavior.

Q3. How to insert or replace images in a PDF in Java?

With Spire.PDF for Java, you can use drawImage() to insert images and PdfImageHelper.replaceImage() to replace existing ones on a specific page.

Q4. Can I annotate a PDF file in Java?

Yes, annotations such as highlights, comments, and stamps can be added using the appropriate annotation classes provided by Spire.PDF for Java.

Q5. Can I extract text and images from an existing PDF file?

Yes, you can. Spire.PDF for Java provides methods to extract text, images, and other elements from PDFs easily. For detailed instructions and code examples, refer to: How to Read PDFs in Java: Extract Text, Images, and More

Get a Free License

To fully experience the capabilities of Spire.PDF for Java without any evaluation limitations, you can request a free 30-day trial license.