In various scenarios, you come across the need of merging two or more PDF documents into a single file. For example, PDF merging allows you to combine similar kinds of documents. Furthermore, you can merge multiple PDFs into a single PDF before sharing it online or sending it to someone. In this article, I’ll demonstrate how to automate this feature and merge multiple PDF files programmatically using Java.
- Merge Two PDF Files into a Single PDF using Java
- Merge Multiple PDF Files using Java
- Use InputStream Objects to Merge PDF Files using Java
Java API to Merge PDF Files
Aspose.PDF for Java is a feature-rich PDF API that lets you merge multiple PDF documents quite easily within a few lines of code. You can either download the API’s JAR or install it in your Maven-based application using the following configuration.
Repository
<repository>
<id>AsposeJavaAPI</id>
<name>Aspose Java API</name>
<url>https://repository.aspose.com/repo/</url>
</repository>Dependency
<dependency>
<groupId>com.aspose</groupId>
<artifactId>aspose-pdf</artifactId>
<version>20.5</version>
<classifier>jdk17</classifier>
</dependency>'Merge Two PDF Files into One PDF in Java
Lets first check out the simple scenario of merging only two PDF files and this can be achieved within a couple of steps.
- Create an instance of the PdfFileEditor class.
- Merge PDF files using PdfFileEditor.concatenate(String firstInputFile, String secInputFile, String outputFile) method.
The following code sample shows how to merge two PDF files into a single PDF using Java.
Merge Multiple PDF Files using Java
In the previous example, we have merged only two PDF files into a single PDF. However, there could be a case when you need to merge more than two PDF files. In such cases, you can pass an array to the PDF files’ paths to the concatenate method. The following are the steps to perform this operation.
- Create an instance of the PdfFileEditor class.
- Put the PDF files’ paths into a string array.
- Merge PDF files using PdfFileEditor.concatenate(String[] inputFiles, String outputFile) method.
The following code sample shows how to merge multiple PDF files into a single PDF using Java.
Merge PDF Files using InputStream in Java
In case you are dealing with the PDF files in the form of InputStream, you can directly pass the InputStream objects and get the merged PDF as an OutputStream object. The following are the steps to merge PDF files loaded into InputStream objects.
- Create an instance of the PdfFileEditor class.
- Load the PDF files into the InputStream objects.
- Merge PDFs using PdfFileEditor.concatenate(InputStream firstInputStream, InputStream secInputStream, OutputStream outputStream) method.
The following code sample shows how to merge PDF files using InputStream objects in Java.
Conclusion
In this article, you have learned how to merge PDF files programmatically using Java. The code samples and step by step guide shows how to merge two or more than two PDF files using physical paths or InputStream objects. You can learn more about the Java PDF Merger library using the documentation.
