How to Merge Two or More PDF Files Together using Java

One of the big benefits of PDF documents is that they can store & compress a variety of different media types. This flexibility means that when we merge compressed PDF documents, we can really combine content from a variety of unique sources such as spreadsheets, PowerPoint slides & image arrays into a single, diverse report/presentation.

Thankfully, creating merged PDF documents at scale is easy when you take advantage of our PDF Merge APIs. These APIs allow you to merge 2 or 2+ PDF files using only the respective file paths & a secure API key (which you can get for free by registering a free account on our website). Below, I’ll demonstrate how you can structure either API call in Java in just a few simple steps.

First things first, let’s begin by installing the Java SDK with Maven. Include the below reference in the pom.xml repository:

<repositories>
    <repository>
        <id>jitpack.io</id>
        <url>https://jitpack.io</url>
    </repository>
</repositories>

Then include a reference in the pom.xml dependency:

<dependencies>
<dependency>
    <groupId>com.github.Cloudmersive</groupId>
    <artifactId>Cloudmersive.APIClient.Java</artifactId>
    <version>v4.25</version>
</dependency>
</dependencies>

To merge no more than two PDF documents, we can use the below examples with exactly two input parameters. First include your imports at the top of your file, then authenticate your API key below that & configure your file paths:

// Import classes:
//import com.cloudmersive.client.invoker.ApiClient;
//import com.cloudmersive.client.invoker.ApiException;
//import com.cloudmersive.client.invoker.Configuration;
//import com.cloudmersive.client.invoker.auth.*;
//import com.cloudmersive.client.MergeDocumentApi;
ApiClient defaultClient = Configuration.getDefaultApiClient();
// Configure API key authorization: Apikey
ApiKeyAuth Apikey = (ApiKeyAuth) defaultClient.getAuthentication("Apikey");
Apikey.setApiKey("YOUR API KEY");
// Uncomment the following line to set a prefix for the API key, e.g. "Token" (defaults to null)
//Apikey.setApiKeyPrefix("Token");
MergeDocumentApi apiInstance = new MergeDocumentApi();
File inputFile1 = new File("/path/to/inputfile"); // File | First input file to perform the operation on.
File inputFile2 = new File("/path/to/inputfile"); // File | Second input file to perform the operation on (more than 2 can be supplied).
try {
    byte[] result = apiInstance.mergeDocumentPdf(inputFile1, inputFile2);
    System.out.println(result);
} catch (ApiException e) {
    System.err.println("Exception when calling MergeDocumentApi#mergeDocumentPdf");
    e.printStackTrace();
}

If we’re merging more than two PDFs, we can instead use the below examples, which include up to 10 file input parameters:

// Import classes:
//import com.cloudmersive.client.invoker.ApiClient;
//import com.cloudmersive.client.invoker.ApiException;
//import com.cloudmersive.client.invoker.Configuration;
//import com.cloudmersive.client.invoker.auth.*;
//import com.cloudmersive.client.MergeDocumentApi;
ApiClient defaultClient = Configuration.getDefaultApiClient();
// Configure API key authorization: Apikey
ApiKeyAuth Apikey = (ApiKeyAuth) defaultClient.getAuthentication("Apikey");
Apikey.setApiKey("YOUR API KEY");
// Uncomment the following line to set a prefix for the API key, e.g. "Token" (defaults to null)
//Apikey.setApiKeyPrefix("Token");
MergeDocumentApi apiInstance = new MergeDocumentApi();
File inputFile1 = new File("/path/to/inputfile"); // File | First input file to perform the operation on.
File inputFile2 = new File("/path/to/inputfile"); // File | Second input file to perform the operation on.
File inputFile3 = new File("/path/to/inputfile"); // File | Third input file to perform the operation on.
File inputFile4 = new File("/path/to/inputfile"); // File | Fourth input file to perform the operation on.
File inputFile5 = new File("/path/to/inputfile"); // File | Fifth input file to perform the operation on.
File inputFile6 = new File("/path/to/inputfile"); // File | Sixth input file to perform the operation on.
File inputFile7 = new File("/path/to/inputfile"); // File | Seventh input file to perform the operation on.
File inputFile8 = new File("/path/to/inputfile"); // File | Eighth input file to perform the operation on.
File inputFile9 = new File("/path/to/inputfile"); // File | Ninth input file to perform the operation on.
File inputFile10 = new File("/path/to/inputfile"); // File | Tenth input file to perform the operation on.
try {
    byte[] result = apiInstance.mergeDocumentPdfMulti(inputFile1, inputFile2, inputFile3, inputFile4, inputFile5, inputFile6, inputFile7, inputFile8, inputFile9, inputFile10);
    System.out.println(result);
} catch (ApiException e) {
    System.err.println("Exception when calling MergeDocumentApi#mergeDocumentPdfMulti");
    e.printStackTrace();
}

With that, you’re all done — no more code required.