Merging PDF Files with Java

in #programming3 years ago (edited)

Merging PDF files is a common task that we usually need to do in our daily activities. Of course, it is possible and fairly easy to merge PDF files in various applications, including Adobe Acrobat or other similar applications. But sometimes you need to automate this task and a programmatic way could save you a lot of trouble when you need to do this very frequently.

Merging PDF Files

As you know, Java added scripting support in Java SE 6. This means that you can use other programming languages on the Java platform.

The most common scripting language used with Java is JavaScript. For this reason, Java is shipped with an out-of-the-box JavaScript engine, called Nashorn.

Today, I needed to merge several PDF documents and I noticed that my old programs that I used to use for this task were, well, old. So I wrote a simple JavaScript file to do the task. It uses the excellent iText library originally written by Bruno Lowagie.

Here is the script:

// merge.js

var File =;
var PdfDocument = com.itextpdf.kernel.pdf.PdfDocument;
var PdfReader = com.itextpdf.kernel.pdf.PdfReader;
var PdfWriter = com.itextpdf.kernel.pdf.PdfWriter;
var PdfMerger = com.itextpdf.kernel.utils.PdfMerger;

function merge(destFilename, sourceFilenames) {
  var file = new File(destFilename).getAbsoluteFile();
  var destDocument = new PdfDocument(new PdfWriter(file));

  var merger = new PdfMerger(destDocument);

  sourceFilenames.forEach(function (sourceFilename) {
    var sourceDocument = new PdfDocument(new PdfReader(new File(sourceFilename)));
    merger.merge(sourceDocument, 1, sourceDocument.getNumberOfPages());


var destFilename = arguments[0];
var sourceFilenames = arguments.slice(1);

merge(destFilename, sourceFilenames);

When using this simple program, you should provide the destination filename as the first argument and the source filenames as the next arguments. For example, if your destination filename is dest.pdf and the source filenames are source1.pdf, source2.pdf, and source3.pdf, then you can run the program on Windows as follows:

set classpath=itext7-io-7.0.2.jar;itext7-kernel-7.0.2.jar;slf4j-api-1.7.2.jar
java -cp %classpath% merge.js -- dest.pdf source1.pdf source2.pdf source3.pdf

Of course, this post was just about using the iText library. Setting the classpath and managing the dependencies is a vast topic in itself and depends on your development environment.


Assalamu alaikum sir,
How are you?

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Thank you. I am just fine. I am currently busy with my day job. Thank you for asking, though. I hope you are doing fine, and I wish you all the best on Steemit!

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ေက်းဇူးတင္ပါတယ္ခင္ဗ်ာthank you

Itext library is great for java and c# library (contains of 4 dlls) called iTextSharp is based on this java library .But greater is use java packages from script languages that i saw here ! thanks for sharing

Thank you. For quick tasks I prefer to use JavaScript over Java, because it is easier to write the code and run.

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great! thanks for the info 😻

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تشکر بابت حمایتتون اقای دکتر❤🌷

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Informative post

سلام اقای کیانی عزیز
استیم اپ هم داره برا اندروید ؟

سلام، شبتون بخیر.

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Thanks for the valuable posts on your page
I am grateful to be here in the community with you with love and respect No monopoly No racism No discrimination This is what we need Love, appreciation, respect and cooperation
I will be happy to join my page and support me permanently
Vielen Dank für die wertvollen Beiträge auf Ihrer Seite
Ich bin dankbar, mit Liebe und Respekt hier in der Gemeinschaft zu sein. Kein Monopol. Kein Rassismus. Keine Diskriminierung. Das ist es, was wir brauchen. Liebe, Wertschätzung, Respekt und Zusammenarbeit
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내 페이지에 참여하고 저를 영구적으로 지원하게되어 기쁩니다.

Thank you

Great article. Thanks for the upvotes as well!

عرض ادب اقای دکتر
سری به بلاگ ما هم بزنید 🌷

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bro support

دکتر با درصد بیشتری حمایتم کن

Good post.

تشکر از لطفتون

Thanks for information @ghasemkiani.

Are you thinking about to create Java classes of your tool?

I mean, it would great to import your project into Java to accomplish the task of merging, without dealing with JavaScript.

I think that's the logical thing to do. But for quick solutions, I prefer JavaScript. Java is more suitable for larger projects. In the recent years, I have mostly used JavaScript, so it is easier for me to write in JavaScript. As you can see, my programming posts are all about JavaScript.


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اگر ممکنه استیم چت رو چک بفرمایید🌷

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لطفا منو هم فالو کنید تا با گسترش جامعه فارسی زبانان به هم دیگه کمک کنیم

یه لایک از طرف برو بکس ایرانی توی ستیمیت
اگه دوست داشتی یه سری به گروهمون بزن

Hey. Much thanks to you, I'm fine. Only somewhat occupied with my interpretation works.


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سلام اقای کیانی
عرض ادب و احترام
اگر ممکنه یک راه ارتباطی فراهم کنید
باهاتون در تماس باشیم
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سلام آقای کیانی .
خوب هستید ؟
عزیز یه سایتی بود که تعداد استیم پاور باید وارد میکردیم بعد مینوشت که این تعداد ارزش لایکت چقدر هست
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واقعا ممنون بابت توجهتون اقای دکتر🌷 من یک سوال برام پیش اومده که چرا پستی قرار نمیدین؟🙈

What is the use case?

Thank you very much

For informative post

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There is a very important information in this post

The most common scripting language used with Java is JavaScript ,thanks for share information with us ,

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Thanks you my post
Cara penulisan nya sangat membantu dan bermanfaat sekali

Well, integrating PDF files is a common thing that should usually be done in our daily activities. Of course ,

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This is a great tutorial! You should repost it to utopian-io!

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wow this post really helped my friend today he was in need to merge something with java i don't know much but i remembered about this post and shared and this helped him wonderful coincidence that i found it thanks a lot for sharing that :D thanks for posting that :) and long time no see

Assalamu alaikum sir, How are you? Thanks for sharing this will be helful to demonstrate to merge multiple PDF documents using iText and Java.

hi my friend.Thanks if you see my page

hi my friend.Thanks if you see my page

thanks man. Great information.

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