I've been using Apache POI for some time to read existing Excel 2003 files programmatically. Now I have a new requirement to create entire .xls files in-memory (still using Apache POI) and then write them to a file at the end. The only problem standing in my way is the handling of cells with dates.

Consider the following code:

```
Date myDate = new Date();
HSSFCell myCell;
// code that assigns a cell from an HSSFSheet to 'myCell' would go here...
myCell.setCellValue(myDate);

```

When I write the workbook containing this cell out to a file and open it with Excel, the cell is displayed as a number. Yes, I do realize that Excel stores its 'dates' as the number of days since January 1 1900 and that is what the number in the cell represents.

**QUESTION: What API calls can I use in POI to tell it that I want a default date format applied to my date cell?**

Ideally I want the spreadsheet cell to be displayed with the same default date format that Excel would have assigned it if a user had manually opened the spreadsheet in Excel and typed in a cell value that Excel recognized as being a date.