Java 使用pagefactory时出现NullPointerException_Java_Selenium_Selenium Webdriver_Page Factory

Java 使用pagefactory时出现NullPointerException

java selenium selenium-webdriver

Java 使用pagefactory时出现NullPointerException,java,selenium,selenium-webdriver,page-factory,Java,Selenium,Selenium Webdriver,Page Factory,代码： BASECLASS.JAVA public class baseclass { public static WebDriver driver; public baseclass(WebDriver driver) { // TODO Auto-generated constructor stub this.driver=driver; PageFactory.initElements(driver, this);

代码：

BASECLASS.JAVA

public class baseclass {
       public static WebDriver driver;
    public baseclass(WebDriver driver) {
        // TODO Auto-generated constructor stub   
        this.driver=driver;
        PageFactory.initElements(driver, this);
    }

    public homepage intializedriver() throws IOException {

        Properties pr=new Properties();
        FileInputStream fs=new FileInputStream("C:\\Users\\Admin\\eclipse - 
        workspace\\learning\\src\\main\\java\\baselearning\\config.properties");
        pr.load(fs);
        String browsername=pr.getProperty("browser");
        if(browsername.equals("chrome")) {
            System.setProperty("webdriver.chrome.driver","D:\\chromedriver.exe");
            driver=new ChromeDriver();
        }
        else if(browsername.equals("firefox")) {
            //firefox code
        }
        driver.get("https://www.flipkart.com/");
        driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);


        return PageFactory.initElements(driver, homepage.class);
    }

}

public class firstTest {

        public WebDriver driver;
        baseclass bs=null;
        homepage hp=null;

        @Test
        public void homepagenaviagation() throws IOException, InterruptedException{
            bs=new baseclass(driver);
            bs.intializedriver();

            hp=new homepage(driver);
            Thread.sleep(3000);
            hp.buttonclose();
            Thread.sleep(3000);
            hp.clicklogin();
    }

}

HOMEPAGE.JAVA

public class homepage extends baseclass {
    public WebDriver driver;
    public homepage(WebDriver driver) throws IOException {
        super(driver);
    }


      @FindBy(xpath="//a[contains(text(),'Login & Signup')]")  
      public WebElement clickLogin;

      @FindBy(xpath="//button[@class='_2AkmmA _29YdH8']") 
      public WebElement buttonclose;

      public void clicklogin() {
           clickLogin.click();

          }
      public void buttonclose() { 
          buttonclose.click();

}

TESTCLASS.JAVA

public class baseclass {
       public static WebDriver driver;
    public baseclass(WebDriver driver) {
        // TODO Auto-generated constructor stub   
        this.driver=driver;
        PageFactory.initElements(driver, this);
    }

    public homepage intializedriver() throws IOException {

        Properties pr=new Properties();
        FileInputStream fs=new FileInputStream("C:\\Users\\Admin\\eclipse - 
        workspace\\learning\\src\\main\\java\\baselearning\\config.properties");
        pr.load(fs);
        String browsername=pr.getProperty("browser");
        if(browsername.equals("chrome")) {
            System.setProperty("webdriver.chrome.driver","D:\\chromedriver.exe");
            driver=new ChromeDriver();
        }
        else if(browsername.equals("firefox")) {
            //firefox code
        }
        driver.get("https://www.flipkart.com/");
        driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);


        return PageFactory.initElements(driver, homepage.class);
    }

}

public class firstTest {

        public WebDriver driver;
        baseclass bs=null;
        homepage hp=null;

        @Test
        public void homepagenaviagation() throws IOException, InterruptedException{
            bs=new baseclass(driver);
            bs.intializedriver();

            hp=new homepage(driver);
            Thread.sleep(3000);
            hp.buttonclose();
            Thread.sleep(3000);
            hp.clicklogin();
    }

}

错误：

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)

欢迎来到Stackoverflow

让我们从

基类开始。Java惯例是以大写字母开头类名，因此将名称更改为BaseClass

public class BaseClass {
    public static WebDriver driver;

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

只有当这个类被其他类继承时，PageFactory.initElements
行才正常。您不想显式地创建此类的实例，所以让我们将其抽象化
此外，创建一个静态的WebDriver将在将来给您带来很多问题。看看我对问题的回答，我在哪里解释原因
public abstract class BaseClass {
    protected WebDriver driver;

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

对于像这样的基类
，我们只需要在页面对象类上使用继承
，就可以对它们进行初始化
方法initializeDriver
应重命名为initializeDriver
，以符合Java命名约定。Camel大小写用于方法名类似的东西

    public homepage intializeDriver() throws IOException {
        Properties pr=new Properties();
        FileInputStream fs=new FileInputStream("C:\\Users\\Admin\\eclipse - 
        workspace\\learning\\src\\main\\java\\baselearning\\config.properties");
        pr.load(fs);
        String browsername=pr.getProperty("browser");

        if(browsername.equals("chrome")) {
            System.setProperty("webdriver.chrome.driver","D:\\chromedriver.exe");
            driver=new ChromeDriver();
        } else if(browsername.equals("firefox")) {
            //firefox code
        }

        driver.get("https://www.flipkart.com/");
        driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);


        return PageFactory.initElements(driver, HomePage.class);
    }

上述方法返回homepage
类，该类也应重命名为homepage

public class homepage extends baseclass {
    public WebDriver driver;
    public homepage(WebDriver driver) throws IOException {
        super(driver);
    }


      @FindBy(xpath="//a[contains(text(),'Login & Signup')]")  
      public WebElement clickLogin;

      @FindBy(xpath="//button[@class='_2AkmmA _29YdH8']") 
      public WebElement buttonclose;

      public void clicklogin() {
           clickLogin.click();

          }
      public void buttonclose() { 
          buttonclose.click();

}

让我们修复主页
类。更改其名称。删除公共WebDriver
，因为您不再需要它了HomePage
class扩展了BaseClass
，该类已包含受保护的WebDriver驱动程序，您可以通过继承访问该驱动程序
public class HomePage extends BaseClass {

    public homepage(WebDriver driver) throws IOException {
        super(driver);
    }


      @FindBy(xpath="//a[contains(text(),'Login & Signup')]")  
      public WebElement clickLogin;

      @FindBy(xpath="//button[@class='_2AkmmA _29YdH8']") 
      public WebElement buttonclose;

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

      public void buttonclose() { 
          buttonclose.click();

}

让我们回到BaseClass
的initializeDriver（）
方法。这里的问题是，使用该方法的最后一行返回HomePage
类：
return PageFactory.initElements(driver, homepage.class);

这一行会导致多个问题，但您需要更深入的面向对象编程知识才能完全理解这个问题。要快速修复
它，只需将方法声明更改为静态
，如下所示：
public static HomePage intializedriver() throws IOException {

现在，测试类
public class firstTest {

        public WebDriver driver;
        baseclass bs=null;
        homepage hp=null;

        @Test
        public void homepagenaviagation() throws IOException, InterruptedException{
            bs=new baseclass(driver);
            bs.intializedriver();

            hp=new homepage(driver);
            Thread.sleep(3000);
            hp.buttonclose();
            Thread.sleep(3000);
            hp.clicklogin();
    }

}

更改名称，正如我前面提到的。
下一件事是利用@Before
注释（JUnit）初始化WebDriver，因为它不是测试的一部分。这是一个先决条件
然后，我们可以使用initializeDriver（）
方法返回的HomePage
类，或者在测试类中初始化它。像这样：
public class FirstTest {
        HomePage hp =null;

        @Before
        public void setUp() {
            hp = HomePage.initializeDriver(); //static method invocation
        }

        @Test
        public void homepagenaviagation() throws IOException, InterruptedException{
            Thread.sleep(3000);
            hp.buttonclose();
            Thread.sleep(3000);
            hp.clicklogin();
    }

}

就这样
我希望有帮助