How to resolve NullPointerException error while implementing POM with cucumber framework

Question

I am getting java.lang.NullPointerException while executing my test case, I am using Page Object Modle with cucumber framework in my maven project, following are the code snippets BoxJunitScript.java

package com.stepDefinition;

public class BoxJunitScipt {
     WebDriver driver;
     WebDriverWait wait;
     LoginPage lp;
     AllFilesPage afp;


 static DriverInstance instance;

    {
        instance = DriverInstance.getinstance();
        driver = instance.getDiver();
        wait = instance.getWait();

    }

 @Before    
 public void setUp() {

        driver.manage().timeouts().pageLoadTimeout(15, TimeUnit.SECONDS);
        lp = new LoginPage(driver);
        afp = new AllFilesPage(driver);
 }




 @Given("user navigates to App box page")
 public void user_navigates_to_App_box_page() {

     driver.manage().window().maximize();
     driver.get("https://app.box.com"); 
     lp.pageVerify();

 }

 @When("user enters username and password given below")
 public void user_enters_username_and_password_given_below(DataTable loginData) {

     List<List<String>> loginData1 = loginData.asLists();  //convert data in list
       for(List<String> row: loginData1) {
           String email = row.get(0);
           String password = row.get(1);
           lp.loginIntoApp(email,password);
       }
 }

 @Then("page with title {string} should open")
 public void page_with_title_should_open(String title) throws InterruptedException {
    Thread.sleep(3000);
     afp.pageVerify(title);

 }

 @When("user clicks on LogOut")
 public void user_clicks_on_LogOut() {
     afp.logoutFromApp();
     driver.quit();
 }
}

LoginPage.java

package com.stepDefinition;

import org.openqa.selenium.NoSuchElementException;
import org.openqa.selenium.StaleElementReferenceException;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.support.FindBy;
import org.openqa.selenium.support.How;
import org.openqa.selenium.support.PageFactory;
import org.openqa.selenium.support.pagefactory.AjaxElementLocatorFactory;
import org.openqa.selenium.support.ui.ExpectedConditions;
import org.openqa.selenium.support.ui.WebDriverWait;

public class LoginPage  {

private WebDriver driver;
WebDriverWait wait;


@FindBy(how=How.NAME, using="login")
WebElement emailTextField;
@FindBy(how=How.CSS, using="button[id='login-submit']")
 WebElement nextButton;
@FindBy(how=How.NAME, using="password")
WebElement passwordTextField;
@FindBy(css="button[id='login-submit-password']")
WebElement logInButton;

public LoginPage(WebDriver driver) {
    this.driver = driver;
    AjaxElementLocatorFactory ajaxDriver = new AjaxElementLocatorFactory(driver, 45);
    PageFactory.initElements(ajaxDriver, LoginPage.class);
}

public void loginIntoApp(String username, String password) {
    emailTextField.sendKeys(username);
    nextButton.click();
    passwordTextField.sendKeys(password);
    logInButton.click();

}

public void pageVerify() {

    System.out.println("Before getting title");
    String title = driver.getTitle();
    System.out.println("After getting title");

    if(title.equals("Box | Login")) 
        System.out.println("Page title is correct");
}

public static void waitUntil(WebElement element, WebDriver driver) {
    new WebDriverWait(driver, 60)
            .ignoring(NoSuchElementException.class)
            .ignoring(StaleElementReferenceException.class)
            .until(ExpectedConditions.visibilityOf(element));
}
}

AllFilePage.java

package com.stepDefinition;

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.pagefactory.AjaxElementLocatorFactory;
import org.openqa.selenium.support.ui.WebDriverWait;


public class AllFilesPage {

WebDriver driver;
 WebDriverWait wait;


@FindBy(css="button[data-resin-target='accountmenu']")
WebElement toggleAccountMenu;
@FindBy(css="a[data-resin-target='logout']")
WebElement logOutlink;

public AllFilesPage(WebDriver driver) {
        this.driver = driver;
        AjaxElementLocatorFactory ajaxDriver = new AjaxElementLocatorFactory(driver, 45);
        PageFactory.initElements(ajaxDriver, AllFilesPage.class);
}

public void logoutFromApp() {
    toggleAccountMenu.click();
    logOutlink.click();
}

public void pageVerify(String title) {
    String Actualtitle = driver.getTitle();
    if(Actualtitle.equals(title)) {
        System.out.println("Page title is correct123");

    } else {
        System.err.println("Page title is not correct");
        }
}

}

CreateInstance.java

package com.stepDefinition;

import com.driver.DriverInstance;

import io.cucumber.core.api.Scenario;
import io.cucumber.java.After;
import io.cucumber.java.Before;
import io.cucumber.java.en.Given;


public class CreateInstance {

    public static String browserName = null;

@Given("Browser is {string}")
public void browsere_is(String browser) {
    // Write code here that turns the phrase above into concrete actions
    if(browserName == null) {
        DriverInstance.setInstance(browser);
        browserName = browser;
    }
    if(browserName!= null && !browserName.equals(browser)) {
        DriverInstance.setInstance(browser);
        browserName = browser;
    }
}

@Before
public void beforeScenario(Scenario sc) {
    System.out.println(sc.getName());
    System.out.println("Runs before all");
}

@After
public void afterScenario(Scenario sc) {
    System.out.println(sc.getStatus());
}
}

DriverInstance.java

package com.driver;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.support.ui.WebDriverWait;

public class DriverInstance {

public static DriverInstance instance;
WebDriver driver;
WebDriverWait wait;

public DriverInstance(String browser) {
    if(browser.equals("firefox")) {
        driver = new FirefoxDriver();
    }
    else if(browser.equals("chrome")) {
        System.setProperty("webdriver.chrome.driver", "D:\\selenium-server\\Driver\\chromedriver.exe");
        driver = new ChromeDriver();
    }
    wait = new WebDriverWait(driver, 60);
}

public static void setInstance(String browser) {
    DriverInstance.instance = new DriverInstance(browser);
}

public static DriverInstance getinstance() {
    return instance;
}

public WebDriver getDiver() {
    return driver;
}

public WebDriverWait getWait() {
    return wait;
}
}

I am getting this error on line lp.pageVerify() in BoxJunitScript.java and when i debug my code i observed that i am getting null value for lp object after this line lp = new LoginPage(driver) in BoxJunitScript.java

Answer 1

I am not sure that you have provided a proper code or you have right understanding of where your exception appears.

As per your code:

{
    instance = DriverInstance.getinstance();
    driver = instance.getDiver();
    wait = instance.getWait();
}

you get a reference to a static field instance = DriverInstance.getinstance(); that is basically you can read as static DriverInstance instance = DriverInstance.getinstance();

So after this line you do not have an object. Thus calling driver = instance.getDiver(); should cause NPE.

You never create an instance of your DriverInstance because the instance can be created in two ways.

1. Calling constructor public DriverInstance(String browser)
2. Calling static method public static void setInstance(String browser)

So I believe you need to reconsider your architecture and use static things only where they are really improve your experience.