@Test
    public void dateFormatFill() {
        // Define the path to the template file.
        // The template should have predefined date formatting.
        String templateFileName = TestFileUtil.getPath() + "demo" + File.separator + "fill" + File.separator + "dateFormat.xlsx";

        // Generate a new output file name with a timestamp to avoid overwriting.
        String fileName = TestFileUtil.getPath() + "dateFormatFill" + System.currentTimeMillis() + ".xlsx";

        // Fill the template with data.
        // The dates in the data will be formatted according to the template's settings.
        EasyExcel.write(fileName).withTemplate(templateFileName).sheet().doFill(data());
    }
Example of filling an Excel template with date formatting.
<p>
This method demonstrates how to fill an Excel template where date fields
are already formatted in the template. The written data will automatically
follow the predefined date format in the template.
fastexcel-test/src/test/java/cn/idev/excel/test/demo/fill/FillTest.java