线程“main”中的异常 java.lang.NullPointerException (SearchCity.java:56) (SearchCity.java:104) [重复]

Question

public class SearchCity {

    public void tc() throws InterruptedException, IOException {
        System.setProperty("webdriver.chrome.driver", "C:\\Selenium\\chromedriver.exe");
        WebDriver driver = new ChromeDriver();
        driver.navigate().to("http://localhost/allmapview/");
        Thread.sleep(3000);

        ArrayList<String> data0 = readExcelData(0);
        ArrayList<String> data1 = readExcelData(1);

        for(int i=0; i<data0.size(); i++) {
            driver.findElement(By.xpath(".//*[@id='from']")).sendKeys(data0.get(i));
            Thread.sleep(3000);

            driver.findElement(By.xpath(".//*[@id='to']")).sendKeys(data1.get(i));
            Thread.sleep(3000);

            driver.findElement(By.xpath(".//*[@id='calculate-route']/div[3]/div/div[2]/button")).click();
            Thread.sleep(8000);

            String strText = driver.findElement(By.id("google_dt")).getText();
            String strText1 = driver.findElement(By.id("mmi_dt_2")).getText();

            FileInputStream fis = new FileInputStream(new File("D:\\Screenshots\\Book1.xlsx"));
            XSSFWorkbook workbook = new XSSFWorkbook (fis);
            XSSFSheet sheet = workbook.getSheetAt(0);
            XSSFRow row = sheet.getRow(1);
            XSSFCell cell = row.getCell(2);
            cell.setCellValue(strText);
            XSSFRow row2 = sheet.getRow(1);
            XSSFCell cell2 = row2.getCell(3);
            cell2.setCellValue(strText1);
            fis.close();
            FileOutputStream fos =new FileOutputStream(new File("D:\\\\Screenshots\\\\Book1.xlsx"));
                workbook.write(fos);
                fos.close();


            File screenshot = ((TakesScreenshot)driver).getScreenshotAs(OutputType.FILE);
            FileUtils.copyFile(screenshot, new
                    File("D:\\Screenshots\\Screen" +i));
            Thread.sleep(2000);

            driver.findElement(By.xpath(".//*[@id='calculate-route']/div[3]/div/div[3]/input")).click();
            Thread.sleep(3000);



        }
    }

    public ArrayList<String> readExcelData(int colNo) throws IOException {
        File src = new File("D:\\Screenshots\\Book1.xlsx");
        FileInputStream fis = new FileInputStream(src);

        XSSFWorkbook wb = new XSSFWorkbook(fis);
        XSSFSheet sheet1 = wb.getSheetAt(0);
        Iterator<Row> rowIterator = sheet1.iterator();
        rowIterator.next();

        ArrayList<String> list = new ArrayList<String>();
        while(rowIterator.hasNext()) {
            list.add(rowIterator.next().getCell(colNo).getStringCellValue());
        }


        System.out.println("List :::"+list);
        return list;

    }



    public static void main(String[] args) throws IOException, InterruptedException {
        // TODO Auto-generated method stub
        SearchCity city = new SearchCity();
        city.tc();

我编写了一个代码来读取一个 excel 文件来填充网页中的一些条目，我想从该网页中获取一些数据并将其写入我的 excel 表中，但我在不同行的代码中得到了NullPointerException ，我认为这不是一个重复的问题，所以请提出一些答案。

线程“主”java lang NullPointerException 中的异常 在 SearchCity SearchCity tc(SearchCity java:56) 在 SearchCity SearchCity main(SearchCity java:104)

Answer 1

首先，您在代码XSSFRow row = sheet.getRow(1); 和XSSFRow row2 = sheet.getRow(1); 中读取同一行两次。这不是必需的。然后，您需要检查 sheet 是否为 null 和 sheet.getRow(1) 是否更安全。接下来，读取行并检查单元格是否为null，如果不是，则设置值。

这可能是您特定问题的解决方案，

if (sheet != null && sheet.getRow(1) != null) {
    XSSFRow row = sheet.getRow(1);

    if (row.getCell(2) != null) {
        XSSFCell cell = row.getCell(2);
        cell.setCellValue(strText);
    }

    if (row.getCell(3) != null) {
        XSSFCell cell2 = row2.getCell(3);
        cell2.setCellValue(strText1);
    }
}