NullPointerException while accessing WebDriverWait instance

Question

In my test framework, I have a DriverInitializer class that initializes the WebDriver and WebDriverWait instances (instead of initializing it on every class). The page object classes extend this class to access the WebDriver.

I'm getting a nullpointer exception thrown while trying to access the WebDriverWait instance. See void method init_webdriver_wait below:

public class DriverInitializer {

    protected WebDriver driver;
    protected WebDriverWait wdw;
    protected final long timeInSeconds = 30;

    public DriverInitializer(WebDriver driver) {
        this.driver = driver;
    }

    public WebDriver getDriver() {
        return driver;
    }

    public PropertyConfig goToHome() {
        PropertyConfig pc = new PropertyConfig(driver);
        pc.getAppUrl();

        return pc;
    }

    public void init_webdriver_wait() {
        try {
            wdw =  new WebDriverWait(driver, timeInSeconds);    
        }
        catch(Exception e) {
           // This error message is being triggered
           // and always says that the WebDriverWait instance is null.
           System.out.println("Error in DriverInitializer " + e.getMessage());
        }       
    }
}

In my second class, the LandingPage page factory class, I extended the DriverInitializer class:

 public class LandingPage extends DriverInitializer {       

    @FindBy(how=How.LINK_TEXT, using="REGISTER")
    WebElement register_link;

    @FindBy(how=How.LINK_TEXT, using="LOGIN")
    WebElement login_link;

    public LandingPage(WebDriver driver) {
        super(driver);
        PageFactory.initElements(driver, this);
    }

    public void locate_register_link() throws InterruptedException {

        try {
            init_webdriver_wait();      
            if(wdw != null) {
                // Sample check if the WebDriverWait instance is null.
                wdw.until(ExpectedConditions.elementToBeClickable(register_link));
                Thread.sleep(3000); 
            }
            else {
                // This error message is triggered.
                // It says that the WebDriverWait instance is null.
                System.out.println("WDW is null -> LandingPage.java");
            }
        }
        catch(Exception e) {
            System.out.println("Error in LandingPage => " + e.getMessage());
        }
    }
}

Why does it always return a null pointer exception on my WebDriverWait instance?

Answer 1

`try{
         init_webdriver_wait();
         if(wdw != null){ // sample check if the webdriverwait instance is null
            wdw.until(ExpectedConditions.elementToBeClickable(register_link));
            Thread.sleep(3000);`

My guess would be that wdw is null because you never set a value to that variable. Could you try: WebdriverWait wdw = init_webdriver_wait();