如果getCellType()包含在null检查中，为什么我要用getCellType()得到这个NullPointerException？

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

public class ExcelReader {
    public static void main(String[] args) {
        try (FileInputStream file = new FileInputStream(new File("example.xlsx"));
             Workbook workbook = new XSSFWorkbook(file)) {

            Sheet sheet = workbook.getSheetAt(0);
            Row row = sheet.getRow(0); // 假设我们要读取第一行的第一个单元格

            if (row != null && row.getCell(0) != null) {
                Cell cell = row.getCell(0);
                int cellType = cell.getCellType();
                System.out.println("Cell Type: " + cellType);
            } else {
                System.out.println("Cell is null");
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}