Selenium java.lang.NullPointerException with PageFactory

问题:

I'm trying to get a hang of PageFactory POM, however something is not working and I can not understand what is wrong.

This is my first POM class for Home Page:

package PageFactory;  import org.openqa.selenium.WebDriver; import org.openqa.selenium.WebElement; import org.openqa.selenium.support.FindBy; import org.openqa.selenium.support.PageFactory;  public class Home_Page_POF {  public WebDriver driver;  @FindBy(css = "div#header-profile a#header-profile-toggle") public WebElement profileToggleButton;  @FindBy(css = "form#loginUserdataForm div.footer div.add-footer a.btn.btn-link.linkicon") public WebElement newRegistrationButton;  public Home_Page_POF(WebDriver driver) { this.driver = driver;  PageFactory.initElements(driver, this); }  } 

This is the second POM class for the Reg. page

package PageFactory;  import org.openqa.selenium.WebDriver; import org.openqa.selenium.WebElement; import org.openqa.selenium.support.FindBy; import org.openqa.selenium.support.PageFactory; import org.openqa.selenium.support.ui.Select;   public class Registration_Page_POF {  public WebDriver driver;  //Personal details WebElements @FindBy(css = "form#personalDetailsForm div.profile.pe div.profile-block.simple.first fieldset#pefield-title select#pesalutation") public WebElement titleDropdown; public Select titleSelect = new Select(titleDropdown);  public Registration_Page_POF(WebDriver driver) { this.driver = driver;  PageFactory.initElements(driver, this); }  } 

And this is the test case:

package Tests;  import PageFactory.Home_Page_POF; import PageFactory.Registration_Page_POF; import org.openqa.selenium.WebDriver; import org.openqa.selenium.chrome.ChromeDriver; import org.openqa.selenium.io.TemporaryFilesystem; import org.openqa.selenium.support.ui.Select; import org.testng.annotations.AfterClass; import org.testng.annotations.BeforeClass; import org.testng.annotations.Test; import java.util.concurrent.TimeUnit;  public class Test_POF {  public WebDriver driver;  Home_Page_POF objHomePage; Registration_Page_POF objRegPage;  @BeforeClass public void browserSetUp() {     System.setProperty("webdriver.chrome.driver", "D:/Install/selenium-2.53.0/drivers/chromedriver.exe");     driver = new ChromeDriver();      driver.manage().window().maximize();     driver.manage().timeouts().implicitlyWait(5, TimeUnit.SECONDS);      driver.navigate().to("http://www.lufthansa.com/");         }  @AfterClass public void broserCleanUp() {     if (driver != null) {         TemporaryFilesystem.getDefaultTmpFS().deleteTemporaryFiles();         driver.close();         driver.quit();     } }  @Test public void Test0001() {      objHomePage = new Home_Page_POF(driver);      objHomePage.profileToggleButton.click();      objHomePage.newRegistrationButton.click();      objRegPage = new Registration_Page_POF(driver);      Select titleSelect = new Select(objRegPage.titleDropdown);      titleSelect.selectByVisibleText("Mr.");  } } 

So the HomePage objects are working fine, I click on two buttons and proceed to registration page. After that I want to select a value from dropdown, but it gives me NullPointerException:

java.lang.NullPointerException at org.openqa.selenium.support.ui.Select.<init>(Select.java:44) at PageFactory.Registration_Page_POF.<init>(Registration_Page_POF.java:17) at Tests.Test_POF.Test0001(Test_POF.java:56) 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:85) at org.testng.internal.Invoker.invokeMethod(Invoker.java:639) at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:816) at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1124) at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:125) at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:108) at org.testng.TestRunner.privateRun(TestRunner.java:774) at org.testng.TestRunner.run(TestRunner.java:624) at org.testng.SuiteRunner.runTest(SuiteRunner.java:359) at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:354) at org.testng.SuiteRunner.privateRun(SuiteRunner.java:312) at org.testng.SuiteRunner.run(SuiteRunner.java:261) at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52) at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:86) at org.testng.TestNG.runSuitesSequentially(TestNG.java:1215) at org.testng.TestNG.runSuitesLocally(TestNG.java:1140) at org.testng.TestNG.run(TestNG.java:1048) at org.testng.IDEARemoteTestNG.run(IDEARemoteTestNG.java:74) at org.testng.RemoteTestNGStarter.main(RemoteTestNGStarter.java:121) 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 com.intellij.rt.execution.application.AppMain.main(AppMain.java:144) 

回答1:

The Problem is you are initializing the varaible titleSelect in class itself. Just Initialize inside constructor or after finding the element;

public class Registration_Page_POF {  public WebDriver driver;  //Personal details WebElements @FindBy(css = "form#personalDetailsForm div.profile.pe div.profile-block.simple.first fieldset#pefield-title select#pesalutation") public WebElement titleDropdown; public Select titleSelect; //Dont initialize here  public Registration_Page_POF(WebDriver driver) { this.driver = driver;  PageFactory.initElements(driver, this); titleSelect = new Select(titleDropdown);//initialize here }  } 

文章来源: Selenium java.lang.NullPointerException with PageFactory