無法將數據寫入到Excel文件細胞

Question

我想寫一個字符串到現有的Excel文件細胞，這裏是我的方法：

public void setSuccessMessageInExcellFile(File uploadFile, HttpServletResponse response) { 


     try { 
      FileInputStream fileInputStream = new FileInputStream(uploadFile); 

      HSSFWorkbook workbook = new HSSFWorkbook(fileInputStream); 
      HSSFSheet excelSheet = workbook.getSheetAt(0); 
      HSSFCell cell = excelSheet.getRow(0).getCell(0); 
      cell.setCellValue("Imported"); 

      fileInputStream.close(); 
      FileOutputStream out = new FileOutputStream(uploadFile); 
      workbook.write(out); 
      out.close(); 
     } catch(Exception ex) { 
      ex.getCause().printStackTrace(); 
     } 

    } 

沒有錯誤，但「進口」文字不可用在我的Excel文件中。

Answer 1

確保您的文件存在，可寫且具有正確的Excel版本。之後，你應該改變你的代碼一樣，因爲你得到一個NullPointerException否則：

public void setSuccessMessageInExcellFile(File uploadFile, HttpServletResponse response) { 


    try { 
     FileInputStream fileInputStream = new FileInputStream(uploadFile); 

     HSSFWorkbook workbook = new HSSFWorkbook(fileInputStream); 
     HSSFSheet excelSheet = workbook.getSheetAt(0); 
     HSSFCell cell = excelSheet.createRow(0).createCell(0); 
     cell.setCellValue("Imported"); 

     fileInputStream.close(); 
     FileOutputStream out = new FileOutputStream(uploadFile); 
     workbook.write(out); 
     out.close(); 
    } catch(Exception ex) { 
     ex.getCause().printStackTrace(); 
    } 
} 

，更好的將被把closables在嘗試像這樣的說法：

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