Java 未处理在Selenium和alter中使用findElements的NullpointerException

在将findElements方法与list一起使用时获取NullPointerException。尝试了POM模型，也得到了同样的错误。对代码的findelements部分进行了注释，并对其进行了测试。我不确定我的代码中有什么错误

代码中定义的警报未处理位置警报，未发现异常

我的代码中需要修复什么

代码：

import java.util.ArrayList;
import java.util.List;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.openqa.selenium.By;
import org.openqa.selenium.Keys;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.interactions.Action;
import org.openqa.selenium.interactions.Actions;
import org.openqa.selenium.support.FindBy;
import org.openqa.selenium.support.How;
import org.openqa.selenium.support.ui.ExpectedConditions;
import org.openqa.selenium.support.ui.Select;
import org.openqa.selenium.support.ui.WebDriverWait;

class CleartripPOM1 {
    WebDriver driver;
    private String url="https://www.cleartrip.com/";
    public CleartripPOM1(WebDriver driver) {
        this.driver=driver;
}

By from=By.xpath("//input[@title='Any worldwide city or airport' and @etitle='From']");
By to=By.xpath("//input[@title='Any worldwide city or airport' and @etitle='To']");
By date=By.xpath("//input[@id='DepartDate']");
By adults=By.id("Adults");
By childerns=By.cssSelector("select[name='childs'][id='Childrens']" );
By infants=By.name("infants");
By search=By.xpath("//input[@id='SearchBtn']");
By airline=By.xpath("//li[@class='vendor']/a");
By depart=By.xpath("//li[@class='depart']/a");
By duration=By.xpath("//li[@class='duration']/a");
By price=By.xpath("//li[@class='price']/a");
private List <WebElement>coupon =driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/td/span"));
private List <WebElement> airName=driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/th/small"));
private List <WebElement> departure=driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/th[@class='depart']"));
private List <WebElement> arrival=driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/th[@class='arrive']"));
private List <WebElement> travelTime=driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/th[@class='duration']"));
private List <WebElement> ticketFare=driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/th[@class='price']"));

public ArrayList<String> airlineNames(List<WebElement>el) {
    ArrayList<String> names= new ArrayList<String>();
    for(WebElement e:el) {
        names.add(e.getText());
    }
    return names;
}

public void url_launch() {
    driver.get(url);
    driver.manage().window().maximize();
//  WebDriverWait wait= new WebDriverWait(driver,20);
//  wait.until(ExpectedConditions.alertIsPresent());
//  Alert alert = driver.switchTo().alert();
//  alert.dismiss();

}
public void actions(By e, String location) {
    Actions act = new Actions(driver);
    Action action= act.click(driver.findElement(e)).sendKeys(location).build();
    action.perform();
}

public void selection(By e,String selection) {
    Select select = new Select(driver.findElement(e));
    select.selectByValue(selection);

}
public void searchFlights() {
    actions(from,"Chennai");
    actions(to,"Madurai");
    actions(date,"25/08/2018");
    driver.findElement(date).sendKeys(Keys.TAB);
    selection(adults,"2");
    selection(childerns,"3");
    selection(infants,"1");
    driver.findElement(search).click();
    WebDriverWait wait= new WebDriverWait(driver,20);
    wait.until(ExpectedConditions.presenceOfElementLocated(By.xpath("//li[@class='vendor']/a")));
    System.out.println(airlineNames(coupon));
    System.out.println(airlineNames(airName));
    System.out.println(airlineNames(departure));
    System.out.println(airlineNames(arrival));
    System.out.println(airlineNames(travelTime));
    System.out.println(airlineNames(ticketFare));

public class TestRunner {

    public static void main(String[] args) {
        WebDriver driver = new ChromeDriver();
        // TODO Auto-generated method stub
        CleartripPOM1 ct= new CleartripPOM1(driver);
        ct.url_launch();
        ct.searchFlights();
    }
}

#1: 在初始化

驱动程序

变量之前，您正在初始化所有实例Web元素，因此它将抛出

NullPointerException

。实例Web元素初始化需要在构造函数内部移动，否则需要在需要特定元素的方法一侧移动

我用两个元素的样本给出了两种方法。请使用以下任一方法更改所有实例元素初始化

例如：

方法1:初始化构造函数中的实例webelement。这样，一个类中的所有方法都可以访问所有webelement

    WebDriver driver;

    private List <WebElement>coupon;
    private List <WebElement> airName;
    private String url="https://www.cleartrip.com/";
    public CleartripPOM1(WebDriver driver) {
        this.driver=driver;
        coupon=driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/td/span"));
        airName=driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/th/small"));
        -----------
        ----------- and so on

    }

编辑：

解决后续问题：

---

仅执行搜索操作后，您将获得结果部分，并且所有列表WebElement都将从结果部分中标识。因此，您需要在执行搜索操作后初始化所有列表WebElement，如下所示

关于Web元素声明，如果您想在不同的方法中访问相同的WebElement，那么您可以将WebElement声明为实例。如果仅在searchFlights方法中列出WebElement范围，那么我建议在searchFlights方法中声明，而不是在实例声明中声明

需要更改搜索方法：

public void searchFlights() {
    actions(from,"Chennai");
    actions(to,"Madurai");
    actions(date,"25/08/2018");
    driver.findElement(date).sendKeys(Keys.TAB);
    selection(adults,"2");
    selection(childerns,"3");
    selection(infants,"1");
    driver.findElement(search).click();
    WebDriverWait wait= new WebDriverWait(driver,20);
    wait.until(ExpectedConditions.presenceOfElementLocated(By.xpath("//li[@class='vendor']/a")));

    coupon =driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/td/span"));
    airName=driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/th/small"));
    departure=driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/th[@class='depart']"));
    arrival=driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/th[@class='arrive']"));
    travelTime=driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/th[@class='duration']"));
    ticketFare=driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/th[@class='price']"));


    System.out.println(airlineNames(coupon));
    System.out.println(airlineNames(airName));
    System.out.println(airlineNames(departure));
    System.out.println(airlineNames(arrival));
    System.out.println(airlineNames(travelTime));
    System.out.println(airlineNames(ticketFare));


}

---

谢谢您能告诉我为什么在代码的这一部分中不处理此警报吗//WebDriverWait wait=new WebDriverWait（driver，20）; // wait.until（ExpectedConditions.alertIsPresent（））；//警报警报=驱动程序。切换到（）。警报（）；//警惕。解散（）@Subburaj我面临的另一个问题是，我为下面的函数调用获取空列表，但它应该返回xpath的字符串值。我已经验证了xpath的正确性，请您在这里帮助System.out.println（airlineNames（优惠券））；System.out.println（airlineNames（airlname））；系统输出打印LN（航空公司（起飞））；系统输出打印LN（航班名称（到达））；系统输出打印LN（航空线名称（旅行时间））；系统输出打印LN（airlineNames（ticketFare））；仅执行搜索操作后，您将获得结果。因此，您需要初始化这两行之间的所有List WebElement wait.until（ExpectedConditions.presenceOfElementLocated（By.xpath（“//li[@class='vendor']/a”）；系统输出打印LN（航空公司（优惠券））；。我也更新了第二个问题的答案。请检查更新后的答案。我已经用上述问题编辑了答案。请检查更新后的答案。如果您对上述答案感到满意，请不要忘记放弃投票，并考虑接受答案。

    ChromeOptions options = new ChromeOptions();
    options.addArguments("--disable-notifications");
    WebDriver driver=new ChromeDriver(options);

public void searchFlights() {
    actions(from,"Chennai");
    actions(to,"Madurai");
    actions(date,"25/08/2018");
    driver.findElement(date).sendKeys(Keys.TAB);
    selection(adults,"2");
    selection(childerns,"3");
    selection(infants,"1");
    driver.findElement(search).click();
    WebDriverWait wait= new WebDriverWait(driver,20);
    wait.until(ExpectedConditions.presenceOfElementLocated(By.xpath("//li[@class='vendor']/a")));

    coupon =driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/td/span"));
    airName=driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/th/small"));
    departure=driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/th[@class='depart']"));
    arrival=driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/th[@class='arrive']"));
    travelTime=driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/th[@class='duration']"));
    ticketFare=driver.findElements(By.xpath("//ul[@class='listView flights']/li/table/tbody/tr/th[@class='price']"));


    System.out.println(airlineNames(coupon));
    System.out.println(airlineNames(airName));
    System.out.println(airlineNames(departure));
    System.out.println(airlineNames(arrival));
    System.out.println(airlineNames(travelTime));
    System.out.println(airlineNames(ticketFare));


}