null pointer exception_using java selenium webdriver with TestNG - selenium

Question

when execute the code below , null pointer exception is occures, as driver of class Pom_MainHerokuapp is always null
testcases:-
package testcases;
import java.util.concurrent.TimeUnit;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.testng.annotations.Test;
import poms.Pom_MainHerokuapp;
import testbase.TestBase;
public class MainHerokuapp extends TestBase {
Pom_MainHerokuapp mainHerokuappObject;
public MainHerokuapp() {
mainHerokuappObject = new Pom_MainHerokuapp(driver);
}
#Test(priority = 0)
public void TestMainpagetitle() {
mainHerokuappObject.VerifyTitles();
}
#Test(priority = 1)
public void TestABTestingText() {
mainHerokuappObject.VerifyTextOfABTesting();
}
}
TestBase class:-
package testbase;
import java.util.concurrent.TimeUnit;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.testng.annotations.BeforeTest;
public class TestBase {
public WebDriver driver;
#BeforeTest
public void setup() {
driver = new FirefoxDriver();
driver.get("https://the-internet.herokuapp.com/");
driver.manage().window().maximize();
driver.manage().timeouts().implicitlyWait(30, TimeUnit.SECONDS);
}
}
Also:
package poms;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.support.FindBy;
import org.openqa.selenium.support.PageFactory;
import org.testng.Assert;
public class Pom_MainHerokuapp {
public WebDriver driver;
String text;
String StringMaintext;
String Stringsubtitle;
#FindBy(xpath = "//html//body//div[2]//div//h1")
WebElement Maintitle;
#FindBy(xpath = "//html//body//div[2]//div//h2")
WebElement Subtitle;
#FindBy(linkText = "A/B Testing")
WebElement ABTesting;
#FindBy(xpath = "//html//body//div[2]//div//div//h3")
WebElement ABTestingText;
create constructor of this class
public Pom_MainHerokuapp(WebDriver driver) {
this.driver = driver;
PageFactory.initElements(driver, this); // Initialization all webelements
}
public void VerifyTitles() {
StringMaintext = Maintitle.getText();
Stringsubtitle = Subtitle.getText();
System.out.println(StringMaintext);
System.out.println(Stringsubtitle);
Assert.assertEquals(StringMaintext, "Welcome to the Internet");
Assert.assertEquals(Stringsubtitle, "Available Examples");
}
public void VerifyTextOfABTesting() {
ABTesting.click();
text = ABTestingText.getText();
System.out.println(text);
Assert.assertEquals(text, "A/B Test Variation 1");
}
}
the error is :-
FAILED: TestMainpagetitle 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.$Proxy7.getText(Unknown Source) at
poms.Pom_MainHerokuapp.VerifyTitles(Pom_MainHerokuapp.java:36) at
testcases.MainHerokuapp.TestMainpagetitle(MainHerokuapp.java:28) at
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at
sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at
java.lang.reflect.Method.invoke(Unknown Source) at
org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:85)
at org.testng.internal.Invoker.invokeMethod(Invoker.java:639) at
org.testng.internal.Invoker.invokeTestMethod(Invoker.java:816) at
org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1124) at
org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:125)
at
org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:108)
at org.testng.TestRunner.privateRun(TestRunner.java:774) at
org.testng.TestRunner.run(TestRunner.java:624) at
org.testng.SuiteRunner.runTest(SuiteRunner.java:359) at
org.testng.SuiteRunner.runSequentially(SuiteRunner.java:354) at
org.testng.SuiteRunner.privateRun(SuiteRunner.java:312) at
org.testng.SuiteRunner.run(SuiteRunner.java:261) at
org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52) at
org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:86) at
org.testng.TestNG.runSuitesSequentially(TestNG.java:1215) at
org.testng.TestNG.runSuitesLocally(TestNG.java:1140) at
org.testng.TestNG.run(TestNG.java:1048) at
org.testng.remote.RemoteTestNG.run(RemoteTestNG.java:112) at
org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:205) at
org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:176)
FAILED: TestABTestingText java.lang.NullPointerException at
org.openqa.selenium.support.pagefactory.DefaultElementLocator.findElement(DefaultElementLocator.java:69)
at
org.openqa.selenium.support.pagefactory.internal.LocatingElementHandler.invoke(LocatingElementHandler.java:38)
at com.sun.proxy.$Proxy7.click(Unknown Source) at
poms.Pom_MainHerokuapp.VerifyTextOfABTesting(Pom_MainHerokuapp.java:46)
at testcases.MainHerokuapp.TestABTestingText(MainHerokuapp.java:33)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at
sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at
java.lang.reflect.Method.invoke(Unknown Source) 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.remote.RemoteTestNG.run(RemoteTestNG.java:112) at
org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:205) at
org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:176)

Answer 1

This isn't hard to explain. The default constructor of your test class MainHerokuapp will be called as soon as it is run, i.e. when driver is still null - before your #BeforeTest method, where driver gets set.
MainHerokuapp and TestBase seem to be mixed-up rather than having a clear separation, so you'd be better off merging them back into one.
Another way is to restore control to the child class by dropping the constructor, moving the #BeforeTest there, and calling up to the parent. This definitely works:
public class MainHerokuapp extends TestBase {
Pom_MainHerokuapp mainHerokuappObject;
#BeforeTest
public void setup() {
super.setup();
mainHerokuappObject = new Pom_MainHerokuapp(driver);
}
#Test(priority = 0)
public void TestMainpagetitle() {
mainHerokuappObject.VerifyTitles();
}
#Test(priority = 1)
public void TestABTestingText() {
mainHerokuappObject.VerifyTextOfABTesting();
}
}
public class TestBase {
public WebDriver driver;
// #BeforeTest
public void setup() {
driver = new FirefoxDriver();
driver.get("https://the-internet.herokuapp.com/");
driver.manage().window().maximize();
driver.manage().timeouts().implicitlyWait(30, TimeUnit.SECONDS);
}
}

Answer 2

I also get the same error while I didnt mention the static but when I wrote
public static WebDriver driver = null;
in TestBase class it was working fine.