poi设置边框

Question

合并单元格时，只有第一格边框可以设置成为黑色，是怎么回事?

Answer 1

我的代码:
HSSFCellStyle cs1 = wb.createCellStyle();
cs1.setBorderBottom(HSSFCellStyle.BORDER_THIN);
cs1.setBorderLeft(HSSFCellStyle.BORDER_THIN);
cs1.setBorderRight(HSSFCellStyle.BORDER_THIN);
cs1.setBorderTop(HSSFCellStyle.BORDER_THIN);

HSSFRow titlerow = sheet.createRow(rowIndex);
titlerow.setHeight((short)0x200);
HSSFCell titlecell = titlerow.createCell((short)0);
titlecell.setEncoding(HSSFCell.ENCODING_UTF_16);
titlecell.setCellValue(title);
sheet.addMergedRegion(new Region((short)0,(short)0,(short)0,(short)10));
titlecell.setCellStyle(cs1);按理说合并成大单元格后应该四周有边框才对,但现在出不来,我到底哪里写错啦?