尝试单击页面中的任何元素时使用“java.lang.NullPointerException”

Question

直到昨天，代码还完全正常运行。现在，当我试图运行任何测试用例时，Selenium（使用Java）在主页本身抛出Java.lang.NullPointerException。下面是一个由于错误而失败的简单测试用例。

下面是我的测试类，它正在调用TestBase类的构造函数，然后初始化驱动程序对象。当控件进入HomePage.ClickSearchLink()方法时，测试结束并出现错误。

package com.ss.qa.testcases;

import org.testng.Assert;
import org.testng.annotations.AfterMethod;
import org.testng.annotations.BeforeMethod;
import org.testng.annotations.Test;
import org.openqa.selenium.chrome.*;
import com.ss.qa.base.TestBase;
import com.ss.qa.pages.HomePage;
import com.ss.qa.pages.SearchPage;

public class SearchPageTest extends TestBase{

HomePage homepage;
SearchPage searchpage;

SearchPageTest(){
    super();
}

@BeforeMethod
public void setUp(){
    initialization();
    homepage = new HomePage();
    searchpage = homepage.clickSearchLink();
}

@Test
public void verifyResultCount() {
    int count = searchpage.countResults("a");
    Assert.assertEquals(count, 15);
}   

@AfterMethod
public void tearDown() {
    driver.quit();
    }
}

下面是我的TestBase类，它正在调用Test基类的构造函数并初始化驱动程序对象

package com.ss.qa.base;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.sql.Driver;
import java.util.Properties;
import java.util.concurrent.TimeUnit;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.chrome.ChromeOptions.*;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.support.events.EventFiringWebDriver;

import com.ss.qa.util.TestUtil;
import com.ss.qa.util.WebEventListener;


public class TestBase {

public static WebDriver driver = null;
public static Properties prop;
public static EventFiringWebDriver e_driver;
public static WebEventListener eventListener;

public TestBase(){       
try {
         prop = new Properties();
         FileInputStream ip = new FileInputStream("D:\\Users\\eclipse- 
workspace\\src\\main\\java\\com\\ss\\qa\\config\\config.properties");
         prop.load(ip);

     } catch (FileNotFoundException e) {
         e.printStackTrace();            
     } catch (IOException e) {
         e.printStackTrace();
     }      
 }

 public static void initialization() {

        String browserName = prop.getProperty("browser");
         if (browserName.equalsIgnoreCase("chrome")) {
              System.setProperty("webdriver.chrome.driver", "C:\\Users\\Downloads\\"chromedriver_win32\\chromedriver.exe");

              driver = new ChromeDriver();  
              System.out.println("driver=" + driver); 
         }       
         else if (browserName.equalsIgnoreCase("FF")) {
              System.setProperty("webdriver.gecko.driver", "C:\\Users\\Downloads\\geckodriver-v0.21.0-win64\\geckodriver.exe");
              driver = new FirefoxDriver();           
         }

         e_driver = new EventFiringWebDriver(driver);
         eventListener = new WebEventListener();
         e_driver.register(eventListener);
         driver = e_driver;

         driver.manage().window().maximize();
         driver.manage().deleteAllCookies();
         driver.manage().timeouts().pageLoadTimeout(TestUtil.PAGE_LOAD_TIMEOUT , TimeUnit.SECONDS);
         driver.manage().timeouts().implicitlyWait(TestUtil.IMPLICIT_WAIT , TimeUnit.SECONDS);
         driver.get(prop.getProperty("url"));
    }

}

<!-- Method in Event Listener class which is showing in error -->

    public void afterFindBy(By arg0, WebElement arg1, WebDriver arg2) {
    System.out.println("Find happened on " + arg1.toString() + " Using method " + arg0.toString());

}

好心建议。

Answer 1

WebEventListener.java:31:保持空检查，您正在使用的元素之一引发空指针异常。

如果您可以在第31行发布WebEventListener.java的打印内容，那么我们就可以更好地检查问题。为此,请更改以下行：

public void afterFindBy(By arg0, WebElement arg1, WebDriver arg2) { 
  System.out.println("Find happened on " + arg1 + " Using method " + arg0); 
}