apache-poi-excel-template Includes useful functions for updating excel file with apache poi like adding rows, adding cols etc.

To import data from a text file into Microsoft Excel, follow this step-by-step guide: First, create a blank spreadsheet in Microsoft Excel and ensure you have the .txt file on your PC.

Edmond Woychowsky walks you through his process, including all the necessary sample code, to convert an XML file to an Excel spreadsheet.

If the DAT file you're trying to open is text, you can convert the file into text in the Microsoft Excel program by first saving it as a CSV file.