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java - Apache POI SXSSF 在刷新行上显示 NullPointerException

转载 作者:行者123 更新时间:2023-12-01 18:21:20 28 4
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我的表中有 500 行。当我使用 setRandomAccessWindowSize(1000) 时,它工作正常。数据已从结果集中成功导出到 Excel 文件中,但是当我使用 setRandomAccessWindowSize(100) 时,它给了我一个NullPointerException 我不知道我做错了什么。请建议正确的方法来执行此操作。

这是我的代码:

workbook = new SXSSFWorkbook(100);      //SXSSF workbook
workbook.setCompressTempFiles(true);
SXSSFSheet spreadsheet = workbook.createSheet("Sheet1"); //Generating Excel file
SXSSFRow row;
SXSSFCell cell;
CellStyle style = workbook.createCellStyle();
Font font = workbook.createFont();//Create font
font.setBold(true);//Make font bold
style.setFont(font);//set it to bold

int y = 1;
if (rs.isBeforeFirst() == true) {
while (rs.next()) {
row = spreadsheet.createRow(0);
cell = row.createCell(0);
cell.setCellValue("SR NO");
cell.setCellStyle(style);
for (int s = 1; s <= rsmd.getColumnCount(); s++) {
cell = row.createCell(s);
cell.setCellValue(rs.getMetaData().getColumnName(+s).toUpperCase());
cell.setCellStyle(style);
}
row = spreadsheet.createRow(y);
cell = row.createCell(0);
cell.setCellValue(y + "");
//spreadsheet.autoSizeColumn(0);
for (int x = 1; x <= rsmd.getColumnCount(); x++) {
cell = row.createCell(x);
String address = new CellReference(cell).formatAsString();
cell.setCellValue(address);
cell.setCellValue(rs.getString(+x));
//spreadsheet.autoSizeColumn(x);
}
y++;
}

FileOutputStream out = new FileOutputStream(new File(destination));
workbook.write(out);
out.close();
workbook.dispose();

最佳答案

我已经更新了上面代码中的 while 循环。它多次写入第 0 行。这就是为什么在第 101 行它给出 NullPointer 异常,因为第 0 行已经被刷新。

这是我的修复-

if (rs.isBeforeFirst() == true) {
while (rs.next()) {
//writing columns
if (rs.isFirst()) {
row = spreadsheet.createRow(0);
cell = row.createCell(0);
cell.setCellValue("SR NO");
cell.setCellStyle(style);
for (int s = 1; s <= rsmd.getColumnCount(); s++) {
cell = row.createCell(s);
cell.setCellValue(rs.getMetaData().getColumnName(+s).toUpperCase());
cell.setCellStyle(style);
}
}
//Writing data
row = spreadsheet.createRow(y);
cell = row.createCell(0);
cell.setCellValue(y + "");
//spreadsheet.autoSizeColumn(0);
for (int x = 1; x <= rsmd.getColumnCount(); x++) {
cell = row.createCell(x);
cell.setCellValue(rs.getString(+x));
//spreadsheet.autoSizeColumn(x);
}
y++;
}

FileOutputStream out = new FileOutputStream(new File(destination));
workbook.write(out);
out.close();
workbook.dispose();

关于java - Apache POI SXSSF 在刷新行上显示 NullPointerException,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/60287789/

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