成功登录页面后第二页中的Selenium WebDriver中出现空指针异常

如何解决以下异常

这是代码

package com;`

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.firefox.FirefoxDriver;

public class Browserfactory {

    static WebDriver driver;
    public static WebDriver startBrowser(String browserName)
    {
        if(browserName.equalsIgnoreCase("firefox"))
        {
            System.setProperty("webdriver.firefox.marionette","geckodriver.exe");
             driver = new FirefoxDriver();

        }
        else if(browserName.equalsIgnoreCase("chrome"))     
        {
            System.setProperty("webdriver.chrome.driver","chromedriver.exe");
             driver = new ChromeDriver();
        }
        return driver;
    }
}

从另一个类访问。 下面的代码是在不同的类中编写的，并将其作为基类访问

我想把Logout方法作为实用工具，当需要注销时，只需调用它就可以了

package com;

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.testng.annotations.AfterTest;
import org.testng.annotations.BeforeTest;
import org.testng.annotations.Test;

public class Guru99 {
//creating a guru99 bank page login verify.
    public WebDriver driver=null;
    private static final String URL="http://demo.guru99.com/v4/";
    @BeforeTest
    //pre-requisition  
    public void launchpage() 
    {   
        WebDriver driver = Browserfactory.startBrowser("firefox");
        driver.get(URL);
        driver.findElement(By.name("uid")).sendKeys("mngr117051");
        driver.findElement(By.name("password")).sendKeys("EhYtErY");
        driver.findElement(By.name("btnLogin")).click();
    }   
    @Test
    public void logout()
    {
        driver.findElement(By.xpath("html/body/div[2]/div/ul/li[15]/a")).click();
    }

}

//Running code through TestNG.

获取错误

FAILED: logout
java.lang.NullPointerException
    at com.Guru99.logout(Guru99.java:26)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:100)
    at org.testng.internal.Invoker.invokeMethod(Invoker.java:646)
    at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:811)
    at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1137)
    at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:129)
    at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:112)
    at org.testng.TestRunner.privateRun(TestRunner.java:753)
    at org.testng.TestRunner.run(TestRunner.java:607)
    at org.testng.SuiteRunner.runTest(SuiteRunner.java:368)
    at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:363)
    at org.testng.SuiteRunner.privateRun(SuiteRunner.java:321)
    at org.testng.SuiteRunner.run(SuiteRunner.java:270)
    at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
    at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:86)
    at org.testng.TestNG.runSuitesSequentially(TestNG.java:1284)
    at org.testng.TestNG.runSuitesLocally(TestNG.java:1209)
    at org.testng.TestNG.runSuites(TestNG.java:1124)
    at org.testng.TestNG.run(TestNG.java:1096)
    at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:132)
    at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:236)
    at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:81)

---

这是因为您在代码中犯了错误

我不明白为什么您在代码中的3个位置声明了驱动程序。每当您一次又一次地声明同一个变量时，它以前的值每次都会被覆盖，这就是您获得

NullPointerException

的原因

我已经修改了你的代码，并验证了工作

   public class Browserfactory {

    public static WebDriver startBrowser(WebDriver driver,String browserName) {
        if (browserName.equalsIgnoreCase("firefox")) {
            System.setProperty("webdriver.firefox.marionette","geckodriver.exe");
            driver = new FirefoxDriver();
        } else if (browserName.equalsIgnoreCase("chrome")){
            System.setProperty("webdriver.chrome.driver", "chromedriver.exe");
            driver = new ChromeDriver();
        }
        return driver;
    }
}

public class Guru99 {
    // creating a guru99 bank page login verify.
    public WebDriver driver = null;
    private static final String URL = "https://demo.guru99.com/v4";

    @BeforeTest
    // pre-requisition
    public void launchpage() {
        driver = Browserfactory.startBrowser(driver,"firefox");
        driver.manage().window().maximize();
        driver.get(URL);
        driver.findElement(By.name("uid")).sendKeys("mngr117051");
        driver.findElement(By.name("password")).sendKeys("EhYtErY");
        driver.findElement(By.name("btnLogin")).click();
    }

    @Test
    public void logout() {
        driver.findElement(By.xpath("html/body/div[2]/div/ul/li[15]/a")).click();
    }

}

---

希望这能对您有所帮助。

这是因为您在代码中犯了错误

我不明白为什么您在代码中的3个位置声明了驱动程序。每当您一次又一次地声明同一个变量时，它以前的值每次都会被覆盖，这就是您获得

NullPointerException

的原因

我已经修改了你的代码，并验证了工作

   public class Browserfactory {

    public static WebDriver startBrowser(WebDriver driver,String browserName) {
        if (browserName.equalsIgnoreCase("firefox")) {
            System.setProperty("webdriver.firefox.marionette","geckodriver.exe");
            driver = new FirefoxDriver();
        } else if (browserName.equalsIgnoreCase("chrome")){
            System.setProperty("webdriver.chrome.driver", "chromedriver.exe");
            driver = new ChromeDriver();
        }
        return driver;
    }
}

public class Guru99 {
    // creating a guru99 bank page login verify.
    public WebDriver driver = null;
    private static final String URL = "https://demo.guru99.com/v4";

    @BeforeTest
    // pre-requisition
    public void launchpage() {
        driver = Browserfactory.startBrowser(driver,"firefox");
        driver.manage().window().maximize();
        driver.get(URL);
        driver.findElement(By.name("uid")).sendKeys("mngr117051");
        driver.findElement(By.name("password")).sendKeys("EhYtErY");
        driver.findElement(By.name("btnLogin")).click();
    }

    @Test
    public void logout() {
        driver.findElement(By.xpath("html/body/div[2]/div/ul/li[15]/a")).click();
    }

}

---

希望这能对你有所帮助。

可能重复的可能重复的可能重复的是，解决了我没有注意到事实上，我认为它会起作用，令人惊讶的是我浪费了2个小时来解决问题，但我无法解决。是的，解决了我没有注意到事实上，我认为它会起作用，令人惊讶的是我浪费了2个小时来解决问题，但我无法解决。