为 selenium webdriver 类获取 java.lang.NullPointerException

Question

I am quite new to Selenium WebDriver. A java.lang.NullPointerException has been troubling me for sometime now, and I cannot understand why. Following are my classes which are quite simple actually:

suiteBase.java

package utilities.suiteBase;

import org.openqa.selenium.WebDriver;

import actions.testPage1.testPage1Actions;
import ui_map.testPage1.TestPage1UI;

public class suiteBase {
    public WebDriver driver;

    protected static TestPage1UI tpui = new TestPage1UI();
    protected static testPage1Actions tpa = new testPage1Actions();
}

testPage1Actions.java

package actions.testPage1;

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebDriver.Timeouts;
import org.openqa.selenium.WebElement;

import utilities.suiteBase.suiteBase;

public class testPage1Actions extends suiteBase {

    public WebDriver driver;
    public void test(WebDriver driver){
        WebElement loc1 = driver.findElement(By.xpath("id('email')"));
        loc1.sendKeys("testing");
        System.out.println("done...");  
    }    
}

TestPage1.java

package testPage1;

import org.openqa.selenium.WebDriver;
import org.testng.annotations.Parameters;
import org.testng.annotations.Test;

import utilities.suiteBase.BrowserOpen;

import utilities.suiteBase.suiteBase;

public class TestPage1 extends suiteBase{
    public WebDriver driver;
    BrowserOpen browse = new BrowserOpen();

    @Parameters({ "browserType", "appURL" })
    @Test(priority = 1)
    public void openBrowser(String browserType,  String appURL){
        browse.setUp(browserType, appURL);  
        System.out.println("Done....");
    }

    @Test(priority = 2)
    public void testCase1() throws InterruptedException{
        driver.wait(1000);
        tpa.test(driver);           
    }
}

I run the TestPage1.java file using XML, where I encounter following error:

java.lang.NullPointerException at testPage1.TestPage1.testCase1(TestPage1.java:28) 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:497) at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:80) at org.testng.internal.Invoker.invokeMethod(Invoker.java:714) at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:901) at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1231) at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:127) at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:111) at org.testng.TestRunner.privateRun(TestRunner.java:767) at org.testng.TestRunner.run(TestRunner.java:617) at org.testng.SuiteRunner.runTest(SuiteRunner.java:334) at org.testng.SuiteRunner. runSequentially(SuiteRunner.java:329) at org.testng.SuiteRunner.privateRun(SuiteRunner.java:291) at org.testng.SuiteRunner.run(SuiteRunner.java:240) at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52) at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:86) at org.testng.TestNG.runSuitesSequentially(TestNG.java:1198) at org.testng.TestNG.runSuitesLocally(TestNG.java:1123) at org.testng.TestNG.run(TestNG.java:1031) at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:126) at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:137) at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:58)

Also I have browserOpen class which I run before TestPage1, in which I declare the WebDriver

package utilities.suiteBase;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.testng.annotations.AfterClass;
import org.testng.annotations.BeforeClass;
import org.testng.annotations.Parameters;
import org.testng.annotations.Test;

import utilities.suiteBase.BrowserOpen;

public class BrowserOpen {

    public WebDriver driver;
    static String driverPath = "E:\\Selenium\\";

    public void setUp(String browserType, String appURL) {
        try {
            setDriver(browserType, appURL);

        } catch (Exception e) {
            System.out.println("Error....." + e.getStackTrace());
        }
    }

    @AfterClass
    public void tearDown() {
        driver.quit();
    }

private void setDriver(String browserType, String appURL) {
    switch (browserType) {
    case "chrome":
        driver = initChromeDriver(appURL);
        break;
    case "firefox":
        driver = initFirefoxDriver(appURL);
        break;
    default:
        System.out.println("browser : " + browserType
                + " is invalid, Launching Firefox as browser of choice..");
        driver = initFirefoxDriver(appURL);
    }
}

private static WebDriver initChromeDriver(String appURL) {
    System.out.println("Launching google chrome with new profile..");
    System.setProperty("webdriver.chrome.driver", driverPath + "chromedriver.exe");
    WebDriver driver = new ChromeDriver();
    driver.manage().window().maximize();
    driver.navigate().to(appURL);
    System.out.println("URL inserted");
//  driver.get(appURL);
    return driver;
}

private static WebDriver initFirefoxDriver(String appURL) {
    System.out.println("Launching Firefox browser..");
    WebDriver driver = new FirefoxDriver();
    driver.manage().window().maximize();
    driver.navigate().to(appURL);
    return driver;
}
}

Answer 1

I never used this technology before, but I see not inited elements.

public WebDriver driver;

WebDriver was not initialized.
You need to initialize them before using. Like:

WebDriver driver = new FirefoxDriver();

Or something else. Check this out: http://www.seleniumhq.org/docs/03_webdriver.jsp

-- UPD: Exception is probably throwing at testCase1() tpa.test(WebDriver). tpa is probably null.

Answer 2

you are using @Parameters({ "browserType", "appURL" }) in your TestPage1 class that will come from testng.xml file . Hope your using this xml file to run your test.

Answer 3

When I declared - public static WebDriver driver; before @BeforeSuite

and then inside the method if we again declared as

WebDriver driver = new FirefoxDriver();

and run the script then it shows me java.lang.NullPointerException error.

Please try below code to resolve :-

driver = new Firefoxdriver();

Example -

public class LearnCheckBox {
    
    public static WebDriver driver;
    
    @BeforeSuite
    
    public static void verify_SetupBrowser() throws InterruptedException
    {
        driver = new FirefoxDriver(); // 
        driver.get("https://learn.letskodeit.com/p/practice");
        driver.manage().window().maximize();
        Thread.sleep(2000);
    }

---

Ashish Bind