Selenium java.lang.NullPointerException使用PageFactory

Question

我試圖得到PageFactory POM的掛起，但是有些東西沒有工作，我不明白什麼是錯的。

這是我的主頁第一POM類：

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); 
} 

} 

這是註冊第二POM類。頁面

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); 
} 

} 

而且是這種測試案例：

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."); 

} 
} 

所以主頁對象工作正常，我點擊兩個按鈕並進入註冊頁面。 之後，我想從下拉式值，但它給了我NullPointerException異常：

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) 

Answer 1

問題是你是初始化varaible titleSelect類本身。只需在構造函數內部或在查找元素後初始化;

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 
} 

}