How to Convert an Excel XLS (97–03) Spreadsheet to Excel XLSX using Java

When you’re using historical data, old-school data formats are just part of the day-to-day grind. Running into Excel XLS spreadsheets from 1997–2003 Windows format means you need to make a hasty conversion to a modern format, or you’ll find yourself completely forgoing compatibility with dozens of modern applications. Thankfully, you can easily transition your old XLS spreadsheets to modern XLSX format with a simple & free API service. Our XLS (97–03) to XLSX API requires only your input file path & Cloudmersive API key (you can get one by registering a free account on our website) as parameters and will return the encoding for a brand new XLSX file. Below, I’ll demonstrate how to utilize this API by structuring your API call with ready-to-run Java code examples.

Let’s start by installing the Cloudmersive Document Conversion API client. First add a reference to the repository in pom.xml:

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

And then add a reference to the dependency in pom.xml:

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

With installation complete, we can now include the imports at the top of our file & call the function. Include your API key in the field shown by the code comments, and then copy your input file path in the inputFile field:

// 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.ConvertDocumentApi;
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");
ConvertDocumentApi apiInstance = new ConvertDocumentApi();
File inputFile = new File("/path/to/inputfile"); // File | Input file to perform the operation on.
try {
    byte[] result = apiInstance.convertDocumentXlsToXlsx(inputFile);
    System.out.println(result);
} catch (ApiException e) {
    System.err.println("Exception when calling ConvertDocumentApi#convertDocumentXlsToXlsx");
    e.printStackTrace();
}

And with that, you’re all done — no more code required. Nice and easy!