Merging Two Or More PDFs Using Lowagie iText API

In this Java tutorial, I am using Lowagie iText API to merge two or more PDF documents into one. Most of my comments related to the program are within the code itself. Please note that you need to have Lowagie iText API downloaded to run this program and for some reason I was able to run it only in JDK1.4, though the official website of iText says that it can run on any version later than 1.4. (It could be a local problem at my environment, please try with higher jdk’s also if you are using one.)

package com.kushal.pdf;

 * @Author Kushal Paudyal
 * Last Modified On 2009-10-07
 * This Requires JDK Version 1.4
 * I was having problem running in some later versions
import java.util.ArrayList;
import java.util.List;

import com.lowagie.text.Document;
import com.lowagie.text.DocumentException;
import com.lowagie.text.pdf.PRAcroForm;
import com.lowagie.text.pdf.PdfCopy;
import com.lowagie.text.pdf.PdfImportedPage;
import com.lowagie.text.pdf.PdfReader;
import com.lowagie.text.pdf.SimpleBookmark;

public class PDFMerger {

public static void main(String args[]) throws IOException,
DocumentException {
String fileOne = "C:/temp/myTimeInOut.pdf";
String fileTwo = "C:/temp/myGanttChart.pdf";
String mergedFileLocation = "C:/temp/myMergedData.pdf";

String filesTobeMerges[] = new String[] { fileOne, fileTwo };

mergeMyFiles(filesTobeMerges, mergedFileLocation);

* Tool that can be used to concatenate
* any number of existing PDF files To One.

public static void mergeMyFiles(String filesToBeMerged[],
String mergedFileLocation) {

System.out.println("Starting To Merge Files...");
System.out.println("Total Number Of Files To Be Merged..."+filesToBeMerged.length+"n");
try {
int pageOffset = 0;
ArrayList masterBookMarkList = new ArrayList();

int fileIndex = 0;
String outFile = mergedFileLocation;
Document document = null;
PdfCopy writer = null;
PdfReader reader = null;

for (fileIndex = 0; fileIndex < filesToBeMerged.length; fileIndex++) {

* Create a reader for the file that we are reading
reader = new PdfReader(filesToBeMerged[fileIndex]);
System.out.println("Reading File -"+filesToBeMerged[fileIndex]);

* Replace all the local named links with the actual destinations.

* Retrieve the total number of pages for this document
int totalPages = reader.getNumberOfPages();

* Get the list of bookmarks for the current document
* If the bookmarks are not empty, store the bookmarks
* into a master list
System.out.println("Checking for bookmarks...");
List bookmarks = SimpleBookmark.getBookmark(reader);
if (bookmarks != null) {
if (pageOffset != 0)
SimpleBookmark.shiftPageNumbers(bookmarks, pageOffset,
System.out.println("Bookmarks found and storing...");
System.out.println("No bookmarks in this file...");
pageOffset += totalPages;

* Merging the files to the first file.
* If we are passing file1, file2 and file3,
* we will merge file2 and file3 to file1.
if (fileIndex == 0) {
* Create the document object from the reader
document = new Document(reader.getPageSizeWithRotation(1));

* Create a pdf write that listens to this document.
* Any changes to this document will be written the file
* outFile is a location where the final merged document
* will be written to.

System.out.println("Creating an empty PDF...");
writer = new PdfCopy(document,
new FileOutputStream(outFile));
* Open this document
* Add the conent of the file into this document (writer).
* Loop through multiple Pages
System.out.println("Merging File: "+filesToBeMerged[fileIndex]);
PdfImportedPage page;
for (int currentPage = 1; currentPage <= totalPages; currentPage++) {
page = writer.getImportedPage(reader, currentPage);

* This will get the documents acroform.
* This will return null if no acroform is part of the document.
* Acroforms are PDFs that have been turned into fillable forms.
System.out.println("Checking for Acroforms");
PRAcroForm form = reader.getAcroForm();
if (form != null)
System.out.println("Acroforms found and copied");
System.out.println("Acroforms not found for this file");

* After looping through all the files, add the master bookmarklist.
* If individual PDF documents had separate bookmarks, master bookmark
* list will contain a combination of all those bookmarks in the
* merged document.
if (!masterBookMarkList.isEmpty())
System.out.println("All bookmarks combined and added");

System.out.println("No bookmarks to add in the new file");


* Finally Close the main document, which will trigger the pdfcopy
* to write back to the filesystem.

System.out.println("File has been merged and written to-"+mergedFileLocation);
} catch (Exception e) {

The output of this program:

Starting To Merge Files...
Total Number Of Files To Be Merged...2

Reading File -C:/temp/myTimeInOut.pdf
Checking for bookmarks...
No bookmarks in this file...
Creating an empty PDF...
Merging File: C:/temp/myTimeInOut.pdf
Checking for Acroforms
Acroforms not found for this file

Reading File -C:/temp/myGanttChart.pdf
Checking for bookmarks...
No bookmarks in this file...
Merging File: C:/temp/myGanttChart.pdf
Checking for Acroforms
Acroforms not found for this file

No bookmarks to add in the new file
File has been merged and written to-C:/temp/myMergedData.pdf

About Lowagie iText:

iText is a library that allows you to generate PDF files on the fly.

iText is an ideal library for developers looking to enhance web- and other applications with dynamic PDF document generation and/or manipulation. iText is not an end-user tool. Typically you won’t use it on your Desktop as you would use Acrobat or any other PDF application. Rather, you’ll build iText into your own applications so that you can automate the PDF creation and manipulation process. For instance in one or more of the following situations:

  • Due to time or size, the PDF documents can’t be produced manually.
  • The content of the document must be calculated or based on user input.
  • The content needs to be customized or personalized.
  • The PDF content needs to be served in a web environment.
  • Documents are to be created in “batch process” mode.

You can use iText to:

  • Serve PDF to a browser
  • Generate dynamic documents from XML files or databases
  • Use PDF’s many interactive features
  • Add bookmarks, page numbers, watermarks, etc.
  • Split, concatenate, and manipulate PDF pages
  • Automate filling out of PDF forms
  • Add digital signatures to a PDF file
  • And much more…

In short: the iText classes are very useful for people who need to generate read-only, platform independent documents containing text, lists, tables and images; or who want to perform specific manipulations on existing PDF documents. The library is especially useful in combination with Java(TM) technology-based Servlets; there’s also a .NET port available: iTextSharp (written in C#).

iText requires JDK 1.4. It’s available for free under a multiple license: MPL and LGPL.