How to Merge Two or More Excel XLSX Files Together using Java

Consolidating Excel reports from multiple sources is a common office administration task. Like most all office administration duties, this task becomes a serious timewaster when many reports are involved — but thankfully, there’s an API for that. With our Merge XLSX Document APIs, you can easily combine two or multiple XLSX files at scale, streamlining the operation while retaining all information/formatting present in the original spreadsheets.

Taking advantage of these APIs is easy; below, I’ve provided code examples & instructions to help structure calls to either API in Java. All you’ll need in addition to the below is an API key, which you can get by registering a free account on our website (with a free account, you’ll receive a limit of 800 API calls per month with zero additional commitments).

We can begin the process by first installing the Java SDK with Maven. Add a reference to the pom.xml repository:

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

Then add a reference to the dependency:

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

Now, if we’re looking to combine no more than two XLSX documents, we can use the code examples below, which include exactly two input file parameters. First add the imports to the top of your file, and right below that you can authenticate your API key in the following snippet.

// 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.mergeDocumentXlsx(inputFile1, inputFile2);
    System.out.println(result);
} catch (ApiException e) {
    System.err.println("Exception when calling MergeDocumentApi#mergeDocumentXlsx");
    e.printStackTrace();
}

To combine any number of files (between 2–10), we can instead use the following code examples to structure our API call (once again beginning by adding the imports & adding the API key). You’ll notice many more file input parameters in these examples to accommodate the larger scale operation:

// 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.mergeDocumentXlsxMulti(inputFile1, inputFile2, inputFile3, inputFile4, inputFile5, inputFile6, inputFile7, inputFile8, inputFile9, inputFile10);
    System.out.println(result);
} catch (ApiException e) {
    System.err.println("Exception when calling MergeDocumentApi#mergeDocumentXlsxMulti");
    e.printStackTrace();
}

You’re all done after following steps to use either of the above code examples — no further contributions are required. Nice & simple.