Blog: PDFMerger
Motive.
A little while ago, I had two PDF documents on my computer, and I needed to combine them into one PDF document. Should be a simple task, I thought. Wrong. I took to Google to figure out how to do it. The first result is to use Adobe Acrobat, but that costs $13. WHO HAS THAT KIND OF MONEY?! So, I scrolled further, to the bottom of the page of search results, and tried one of the free alternatives that claimed it could complete the simple task of "make 2 small pdf into one big pdf". It didn't work. So I tried a different one. It, too, did not work. I tried a third, and Windows Defender flagged it as a virus.
So, defeated, I went to my dad's office and sheepishly asked if I could use his company copy of Adobe Acrobat to combine the documents. He obliged, but I did not forget the ordeal that I went through that day.
This is a story of spite.
Research.
In the back of my head, I had a feeling that this project was going to be annoying. I had some experience dealing with Word documents from an earlier project, so I buckled down and began to research how to effciently deal with PDF documents in code. That's when I stumbled across PDFBox, an open-source PDF library from Apache. PDFBox literally had everything I could possibly need, including a way of merging multiple PDFs into a single PDF.
Disbelief.
Upon reading about how to use PDFBox, I was shocked, absolutely positively bewildered at how easy it was to combine PDF documents. There was an entire class dedicated specifically to that! In fact, here, just look at the code:
That's it. That is literally all of the code that you need to combine AS MANY PDF FILES AS YOU WANT INTO A SINGLE PDF FILE. That's it. Nine lines of code, and two of them are lone curly braces. The fact that none of the other PDF merger apps were able to function correctly when this is the solution baffles me.
Polish.
With the merging taken care of, I could have very easily wrapped this up in a simple command line app and been done in under half an hour. But then I thought about the ordeal I went through to get myself here. I had to make something more polished than that, spite demanded it.
Since I was already writing in Java to use PDFBox, I went ahead whipped up a quick GUI for this tool using Swing. Nothing too fancy, I wanted to keep this as simple of a tool as possible. With the GUI, the user would be able to open as many PDF files as they want, choose the order they will appear in, and export them to a single PDF.
Accomplishing this was pretty simple. As the user opens files, we store the file paths with an ArrayList. This allows us to easily re-order files by simply swapping items on the list. Once we go to export, we simply pass that list into the function above, and boom. One merged PDF. All that was left was to wrap it all up nicely with Launch4j, and I was done. All in, took me about 3 hours.
You can download the spawn of my frustration by clicking the button below. There's a Windows executable that has a bundled Java runtime, or alternatively you can download the .jar file to run on other platforms (Java 18 or later required).
