selenium中页面对象TestNG中的空指针异常

Question

我已经创建了两个页面对象类，并尝试使用这些页面对象类中的方法单击某些菜单链接，并且我得到了一个空点异常错误以下是代码段。我执行了leftmenulink类文件

leftmenulink class

package leftmenulinks;

import java.util.concurrent.TimeUnit;

import org.openqa.selenium.By;
import org.openqa.selenium.JavascriptExecutor;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.support.ui.ExpectedConditions;
import org.openqa.selenium.support.ui.WebDriverWait;
import org.testng.annotations.AfterMethod;
import org.testng.annotations.BeforeMethod;
import org.testng.annotations.Test;

import pageclasses.LeftMenuPage;
import pageclasses.LoginPage;

public class LeftMenuLinks {
    WebDriver driver;
    String baseUrl;
    JavascriptExecutor js;
    LoginPage login;
    LeftMenuPage menu;

@BeforeMethod
public void beforeMethod() {
    System.setProperty("webdriver.gecko.driver", "geckodriver-v0.15.0-win32\\geckodriver.exe");
    driver = new FirefoxDriver();
    login = new LoginPage(driver);
    menu = new LeftMenuPage(driver);

    baseUrl = "";
    driver.manage().window().maximize();
    driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);
    driver.get(baseUrl);
}

@Test
public void f() throws Exception {

        login.giveUsername();
        login.givePw();
        login.clickLogin();

      Thread.sleep(3000);
      System.out.println("done0");

      menu.clickCustomerview();

      WebDriverWait wait = new WebDriverWait(driver, 10);
      WebElement elem2 = wait.until(ExpectedConditions.visibilityOfElementLocated(By.xpath("//div[@id='rt-modal']/div/a")));

      elem2.click();

      menu.clickDashboard();

}

@AfterMethod
public void afterMethod() {
    //driver.quit();

}

}

Leftmanupage对象类

    package pageclasses;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.support.FindBy;
import org.openqa.selenium.support.PageFactory;

public class LeftMenuPage {

    WebDriver driver;

    public LeftMenuPage(WebDriver driver){
        driver = this.driver;
        PageFactory.initElements(driver, this);
    }

    @FindBy(xpath = "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://']")
    WebElement dashboard;

    @FindBy(xpath = "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://']")
    WebElement customerView;

    @FindBy(xpath = "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://']")
    WebElement customerFeedback;

    @FindBy(xpath = "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://']")
    WebElement offerBuilder;

    @FindBy(xpath = "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://']")
    WebElement newsBuilder;

    @FindBy(xpath = "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://']")
    WebElement eventsBuilder;

    @FindBy(xpath = "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://']")
    WebElement smsTemplateBuilder;

    @FindBy(xpath = "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://']")
    WebElement emailTemplateBuilder;

    @FindBy(xpath = "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://']")
    WebElement targetListBuilder;

    @FindBy(xpath= "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://']")
    WebElement campaignManager;

    @FindBy(xpath = "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://']")
    WebElement referralCampaignManager;

    @FindBy(xpath = "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://']")
    WebElement loyalty;

    @FindBy(xpath = "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://']")
    WebElement advertising;

    @FindBy(xpath = "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://']")
    WebElement products;

    @FindBy(xpath = "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://']")
    WebElement merchants;

    @FindBy(xpath = "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://]")
    WebElement partners;

    @FindBy(xpath = "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://']")
    WebElement contentCreation;  

    @FindBy(xpath = "//div[@id='sidebar']/div[3]/div[1]//a[@href='http://']")
    WebElement tour;




    public void clickDashboard() {
        dashboard.click();
    }

    public void clickCustomerview(){
        customerView.click();
    }

    public void clickFeedback(){
        customerFeedback.click();
    }

    public void clickOffer(){
        offerBuilder.click();
    }

    public void clickNews(){
        newsBuilder.click();
    }

    public void clickEvents(){
        eventsBuilder.click();
    }

    public void clickSms(){
        smsTemplateBuilder.click();
    }

    public void clickEmail(){
        emailTemplateBuilder.click();
    }

    public void clickList(){
        targetListBuilder.click();
    }

    public void clickCampaign(){
        campaignManager.click();
    }

    public void clickReferral(){
        referralCampaignManager.click();
    }

    public void clickLoyalty(){
        loyalty.click();
    }

    public void clickAds(){
        advertising.click();
    }

    public void clickProducts(){
        products.click();
    }

    public void clickMerchants(){
        merchants.click();
    }

    public void clickPartners(){
        partners.click();
    }

    public void clickContent(){
        contentCreation.click();
    }

    public void clickTour(){
        tour.click();
    }
}

登录页面对象类

package pageclasses;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.support.FindBy;
import org.openqa.selenium.support.PageFactory;

public class LoginPage {
    WebDriver driver;

    @FindBy(id="email")
    WebElement inputusername;

    @FindBy(id="password")
    WebElement inputpw;

    @FindBy(xpath="//div[@class='control-group large-12']//input[@value='Login']")
    WebElement loginbtn;

    public LoginPage(WebDriver driver){
        this.driver = driver;
        PageFactory.initElements(driver, this);
    }

    public void giveUsername() {
        inputusername.sendKeys("");

    }

    public void givePw() {
        inputpw.sendKeys("");

    }

    public void clickLogin() {
        loginbtn.click();
    }

}

错误是

java.lang.NullPointerException
    at org.openqa.selenium.support.pagefactory.DefaultElementLocator.findElement(DefaultElementLocator.java:69)
    at org.openqa.selenium.support.pagefactory.internal.LocatingElementHandler.invoke(LocatingElementHandler.java:38)
    at com.sun.proxy.$Proxy7.click(Unknown Source)
    at pageclasses.LeftMenuPage.clickCustomerview(LeftMenuPage.java:78)
    at leftmenulinks.LeftMenuLinks.f(LeftMenuLinks.java:47)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:108)
    at org.testng.internal.Invoker.invokeMethod(Invoker.java:661)
    at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:869)
    at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1193)
    at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:126)
    at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:109)
    at org.testng.TestRunner.privateRun(TestRunner.java:744)
    at org.testng.TestRunner.run(TestRunner.java:602)
    at org.testng.SuiteRunner.runTest(SuiteRunner.java:380)
    at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:375)
    at org.testng.SuiteRunner.privateRun(SuiteRunner.java:340)
    at org.testng.SuiteRunner.run(SuiteRunner.java:289)
    at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
    at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:86)
    at org.testng.TestNG.runSuitesSequentially(TestNG.java:1301)
    at org.testng.TestNG.runSuitesLocally(TestNG.java:1226)
    at org.testng.TestNG.runSuites(TestNG.java:1144)
    at org.testng.TestNG.run(TestNG.java:1115)
    at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:132)
    at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:230)
    at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:76)