尝试为两个页面运行两个类时（登录页面和主页）获取空指针异常 [英] Getting null pointer exception when tried running two classes for two pages (login page and home page)

问题描述

在运行单个类时它运行正常但是当我运行两个类（Login和Home页面）时它会抛出空指针异常，看起来第二个类出了问题，请帮我解决这个问题，谢谢你提前。

On running single class it run's fine but when i run two classes of (Login and Home page) it throws null pointer exception, it seem's that something has gone wrong for the second class, Kindly help me to solve this, Thanks in advance.

package Utilities;

import java.util.concurrent.TimeUnit;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.firefox.FirefoxDriver;

public class Browserfctry {

	public static WebDriver startApplication(WebDriver dr, String browsername, String url)

	{
		if (browsername.equals("chrome")) {
			System.setProperty("webdriver.chrome.driver", "/home/ibrahim/eclipse-workspace/chromedriver");
			dr = new ChromeDriver();
		} else if (browsername.equals("firefox")) {
			System.setProperty("webdriver.gecko.driver", "/home/ibrahim/eclipse-workspace/geckodriver");
			dr = new FirefoxDriver();
		} else {
			System.out.println("we do not support this browser");
		}
		dr.manage().timeouts().pageLoadTimeout(30, TimeUnit.SECONDS);
		dr.manage().window().maximize();
		dr.get(url);
		dr.manage().timeouts().implicitlyWait(30, TimeUnit.SECONDS);
		return dr;

	}

//	public static void quitbrowser(WebDriver dr)
//	{
//	dr.quit();
//	
}

我尝试过：



我的基础类：

What I have tried:

My base class:

package Pages;

import org.openqa.selenium.WebDriver;
import org.testng.annotations.BeforeSuite;

import Utilities.Browserfctry;

public class BaseClass {
	public WebDriver dr;

	@BeforeSuite
	public void start() {
		dr = Browserfctry.startApplication(dr, "chrome", "http://192.168.11.92:3003");
	}

//@AfterClass
//	public void terminate()
//	{
//		Browserfctry.quitbrowser(dr);
//		
//	}
}

我的主页类

My home page class

package Pages;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.support.FindBy;

public class HomePageTR {
	WebDriver driver;

	public HomePageTR(WebDriver dr) {
		this.driver = dr;
	}

	@FindBy(xpath = "//span[@class='glyphicon glyphicon-th']")
	WebElement Homemenuicon;

	@FindBy(xpath = "//span[@class='glyphicon glyphicon-user']")
	WebElement Profileicon;

	@FindBy(xpath = "//span[@class='glyphicon glyphicon-cog']")
	WebElement Settingsicon;

	@FindBy(xpath = "//span[@class='glyphicon glyphicon-off']")
	WebElement Logouticon;

	@FindBy(xpath = "//span[@class='glyphicon glyphicon-menu-left']")
	WebElement Sidemenucollider;

	@FindBy(xpath = "//li[@data-section='dataset']")
	WebElement SDMDataAccessicon;

	@FindBy(xpath = "//li[@data-section='metadataWizard']")
	WebElement SDMMetadataicon;

	@FindBy(xpath = "//li[@data-section='analysisWizard']")
	WebElement SDMMotifexplorericon;

	@FindBy(xpath = "(//img)[@src='/images/home/library.png'][1]")
	WebElement SDMMotiflibrary;

	@FindBy(xpath = "//li[@data-section='dashboardSelect']")
	WebElement SDMDashboards;

	@FindBy(xpath = "//a[@data-section='dataset']")
	WebElement Dataaccessicon;

	@FindBy(xpath = "//a[@data-section='metadataWizard']")
	WebElement Metadataicon;

	@FindBy(xpath = "//a[@data-section='analysisWizard']")
	WebElement Motifexplorericon;

	@FindBy(xpath = "//a[@data-section='browser']")
	WebElement Motiflibraryicon;

	@FindBy(xpath = "//a[@data-section='dashboardSelect']")
	WebElement Dashboardicon;

//nextpage reference objects

	@FindBy(xpath = "//a[@data-name='dataAccess']")
	WebElement dataaccesrfrnc;

	@FindBy(xpath = "//div[@class='main-menu-logo']")
	WebElement Logo;

	@FindBy(xpath = "//div[@class='row icon-row']")
	WebElement d1;

	public String dataiconchk() throws InterruptedException {
		Thread.sleep(3000);

		System.out.println(d1.isDisplayed());
		System.out.println(Dataaccessicon.isDisplayed());
		System.out.println("dataicon reached");
		Dataaccessicon.click();
		System.out.println("datacliked");
		String chumma = dataaccesrfrnc.getText();
		return chumma;

	}

}

我的主页测试用例

My home page Test case

package Testcases;

import org.openqa.selenium.support.PageFactory;
import org.testng.Assert;
import org.testng.annotations.Test;

import Pages.BaseClass;
import Pages.HomePageTR;

public class HomePageTestTR extends BaseClass {
	HomePageTR homepagetr;

	@Test(priority = 6)
	public void dataiconchk() throws InterruptedException {

		homepagetr = PageFactory.initElements(dr, HomePageTR.class);
		String dataaccessheader = homepagetr.dataiconchk();

		Assert.assertEquals(dataaccessheader, "Data Access");

		System.out.println("data acces icon checked");

	}

}

我的错误：

My error:

dataiconchk
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.$Proxy8.isDisplayed(Unknown Source)
	at Pages.HomePageTR.dataiconchk(HomePageTR.java:77)
	at Testcases.HomePageTestTR.dataiconchk(HomePageTestTR.java:18)
... Removed 25 stack frames

推荐答案

Proxy8.isDisplayed（未知来源）
在Pages.HomePageTR.dataiconchk（HomePageTR.java:77）
at Testcases.HomePageTestTR.dataiconchk （HomePageTestTR.java:18）
...删除了25个堆栈帧

Proxy8.isDisplayed(Unknown Source) at Pages.HomePageTR.dataiconchk(HomePageTR.java:77) at Testcases.HomePageTestTR.dataiconchk(HomePageTestTR.java:18) ... Removed 25 stack frames

这是我们遇到的最常见的问题之一，它是也是我们最不能回答的那个，b你最有能力回答自己。



让我解释一下错误的含义：你试图使用变量，属性或方法返回值但是它包含null - 这意味着变量中没有类的实例。

它有点像一个口袋：你的衬衫里有一个口袋，用来握笔。如果你进入口袋并发现那里没有笔，你就不能在一张纸上签名 - 如果你尝试的话，你会得到非常有趣的外观！空口袋给你一个空值（这里没有笔！）所以你不能做任何你检索笔通常做的事情。它为什么空？这就是问题 - 可能是你今天早上离开家时忘了拿起你的笔，或者你昨晚把它拿到昨天的衬衫口袋里时可能会把笔留下来。



我们无法分辨，因为我们不在那里，更重要的是，我们甚至看不到你的衬衫，更不用说口袋里的东西了！



回到计算机，你做了同样的事情，不知何故 - 我们看不到你的代码，更不用说运行它了，找不到包含null的东西。

但是你可以 - 在调试器中运行你的程序，当它失败时，调试器会向你显示它发现问题的行。然后，您可以开始查看它的各个部分，以查看哪个值为null，并开始回顾代码以找出原因。因此，在包含错误行的方法的开头放置一个断点，然后从头再次运行程序。这一次，它会在错误发生前停止，让你通过查看代码来查看你的值来检查发生了什么。



但是我们不能这样做那 - 我们没有您的代码，如果我们拥有它，我们不知道如何使用它，我们没有您的数据。所以尝试一下 - 看看你能找到多少信息！

This is one of the most common problems we get asked, and it's also the one we are least equipped to answer, but you are most equipped to answer yourself.

Let me just explain what the error means: You have tried to use a variable, property, or a method return value but it contains null - which means that there is no instance of a class in the variable.
It's a bit like a pocket: you have a pocket in your shirt, which you use to hold a pen. If you reach into the pocket and find there isn't a pen there, you can't sign your name on a piece of paper - and you will get very funny looks if you try! The empty pocket is giving you a null value (no pen here!) so you can't do anything that you would normally do once you retrieved your pen. Why is it empty? That's the question - it may be that you forgot to pick up your pen when you left the house this morning, or possibly you left the pen in the pocket of yesterdays shirt when you took it off last night.

We can't tell, because we weren't there, and even more importantly, we can't even see your shirt, much less what is in the pocket!

Back to computers, and you have done the same thing, somehow - and we can't see your code, much less run it and find out what contains null when it shouldn't.
But you can - run your program in the debugger and when it fails, the debugger will show you the line it found the problem on. You can then start looking at the various parts of it to see what value is null and start looking back through your code to find out why. So put a breakpoint at the beginning of the method containing the error line, and run your program from the start again. This time, it will stop before the error, and let you examine what is going on by stepping through the code looking at your values.

But we can't do that - we don't have your code, we don't know how to use it if we did have it, we don't have your data. So try it - and see how much information you can find out!

homepagetr = PageFactory.initElements(dr, HomePageTR.class);
String dataaccessheader = homepagetr.dataiconchk();

粗略猜测上述方法之一不会返回有效的引用。您的代码无法检查的内容。

At a rough guess one of the above methods does not return a valid reference. Something your code fails to check for.

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