java我在访问具有值的单元格时遇到空指针异常？

Question

我正在使用ApachePOI库从EXCEL工作表中获取数据。我已经附上了突出显示黄色部分的EXCEL表。我试图从EXCEL工作表中提取所有数据，但没有从突出显示的部分获取数据。当试图访问这些单元格时，它会出现空指针异常

样本文件： Document

示例代码

FileInputStream inputStream=新的FileInputStream（文件）

        Workbook workbook = new XSSFWorkbook(inputStream);
        Sheet firstSheet = workbook.getSheetAt(0);
        Iterator<Row> iterator = firstSheet.iterator();

        while (iterator.hasNext()) {
            Row nextRow = iterator.next();
            Iterator<Cell> cellIterator = nextRow.cellIterator();

            while (cellIterator.hasNext()) {
                Cell cell = cellIterator.next();

                System.out.print(cell.getStringCellValue());
                System.out.print(",");
            }
            System.out.println();
        }

        workbook.close();
        inputStream.close();

当您运行上述程序时，您将得到一些未从excel表中提取的字段（突出显示的部分）。当您显式地尝试访问这些单元格时，将出现空指针异常

Answer 1

无法复制这种行为。如果System.out.print(cell.getStringCellValue());抛出一个NPE，那么cell必须是null。但是cell根据您的代码不能是null，因为Row.cellIterator只在存在且不存在的单元格上迭代

已下载SAMPLE.xlsx并使用Busy Developers' Guide - Getting the cell contents中的代码。此代码读取所有单元格时不会出现问题

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.util.*;

import java.io.FileInputStream;

class ReadExcelExampleDataFormatter {

 public static void main(String[] args) throws Exception {

  Workbook wb  = WorkbookFactory.create(new FileInputStream("SAMPLE.xlsx"));

  DataFormatter formatter = new DataFormatter();
  FormulaEvaluator evaluator = wb.getCreationHelper().createFormulaEvaluator();

  Sheet sheet = wb.getSheetAt(0);
  for (Row row : sheet) {
   for (Cell cell : row) {
    CellReference cellRef = new CellReference(row.getRowNum(), cell.getColumnIndex());
    System.out.print(cellRef.formatAsString());
    System.out.print(" - ");
    // get the text that appears in the cell by getting the cell value and applying any data formats (Date, 0.00, 1.23e9, $1.23, etc)
    String text = formatter.formatCellValue(cell);
    System.out.println(text);
   }
  }
  wb.close();
 }
}

部分结果（您的第一个黄色范围）：

A15 - Report
Summary
B15 - Real Estate
C15 - Count
D15 - 3
E15 - 0
F15 - 2
A16 - 
B16 - 
C16 - Balance
D16 - $94,263.00
E16 - $0.00
F16 - $94,263.00
A17 - 
B17 - 
C17 - Current
D17 - 2
E17 - 0
F17 - 2
A18 - 
B18 - 
C18 - Delinquent
D18 - 0
E18 - 0
F18 - 0