java.lang.NullPointerException @Test

Question

您好我正在尝试使用TestNG运行以下代码，但它给出的所有内容都是java.lang.NullPointerException错误。 Before方法得到了解决。之后，它显示以下错误。出了什么问题。请帮忙！

错误：

java.lang.NullPointerException
at lokbo.Login.afterMethod(Login.java:50)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.base/java.lang.reflect.Method.invoke(Unknown Source)
    at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:108)
    at org.testng.internal.Invoker.invokeConfigurationMethod(Invoker.java:523)
    at org.testng.internal.Invoker.invokeConfigurations(Invoker.java:224)
    at org.testng.internal.Invoker.invokeMethod(Invoker.java:731)
    at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:877)
    at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1201)
    at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:125)
    at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:109)
    at org.testng.TestRunner.privateRun(TestRunner.java:776)
    at org.testng.TestRunner.run(TestRunner.java:634)
    at org.testng.SuiteRunner.runTest(SuiteRunner.java:425)
    at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:420)
    at org.testng.SuiteRunner.privateRun(SuiteRunner.java:385)
    at org.testng.SuiteRunner.run(SuiteRunner.java:334)
    at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
    at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:86)
    at org.testng.TestNG.runSuitesSequentially(TestNG.java:1318)
    at org.testng.TestNG.runSuitesLocally(TestNG.java:1243)
    at org.testng.TestNG.runSuites(TestNG.java:1161)
    at org.testng.TestNG.run(TestNG.java:1129)
    at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:114)
    at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:251)
    at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:77)

代码：

 package lokbo;
 import java.util.concurrent.TimeUnit;
 import org.testng.annotations.Test;

 import org.openqa.selenium.By;
 import org.openqa.selenium.WebDriver;
 import org.openqa.selenium.chrome.ChromeDriver;
 import org.testng.annotations.AfterMethod;

 import org.testng.annotations.BeforeMethod;



 public class Login 
{
  public  WebDriver driver;

 @BeforeMethod
 public void beforeMethod()  {
 System.setProperty("webdriver.chrome.driver", "E:\\RF 
 AUTOMATION\\chromedriver_win32\\chromedriver.exe");
    WebDriver driver=new ChromeDriver();
    String baseurl= "http://dev.idrottonline.se/";
    driver.get(baseurl);
    driver.manage().timeouts().implicitlyWait(300, TimeUnit.SECONDS);


    String expectedTitle = "Idrottonline2 - Svenskidrott";
    String actualTitle="";
    actualTitle=driver.getTitle();
    if(actualTitle.contentEquals(expectedTitle))
    //if(expectedTitle.isDisplayed())   
    {
        System.out.println("Test pass");
    }
    else
    {
        System.out.println("Test Fail");
    }
}
  @Test
  public void login() {

  driver.findElement(By.id("IdrottOnline-LoginBoxTarget")).click();
    driver.findElement(By.id("ioui-access-username")).sendKeys("lagorf01");
    driver.findElement(By.id("ioui-access-password")).sendKeys("Dumbo753");
    driver.findElement(By.xpath(".//*[@id='ioui-access-login']/fieldset/div[5]/div/button")).click();
 }
 @AfterMethod
 public void afterMethod() {
  driver.manage().deleteAllCookies();
  driver.quit();
}
 }