XSSFSheet sheet = new XSSFSheet(ctSheet, ctWorksheet, (XSSFWorkbook) workbook);
StylesTable stylesTable = (StylesTable) workbook.getStylesSource();
XSSFFont font = new XSSFFont();
font.setFontName("Cambria");
stylesTable.putFont(font);
CTXf cellStyleXf = CTXf.Factory.newInstance();
cellStyleXf.setFontId(1);
cellStyleXf.setFillId(0);
cellStyleXf.setBorderId(0);
cellStyleXf.setNumFmtId(0);
stylesTable.putCellStyleXf(cellStyleXf);
CTXf cellXf = CTXf.Factory.newInstance();
cellXf.setXfId(1);
stylesTable.putCellXf(cellXf);
XSSFCellStyle cellStyle = new XSSFCellStyle(1, 1, stylesTable);
assertEquals(1, cellStyle.getFontIndex());
sheet.setDefaultColumnStyle((short) 3, cellStyle);