NullPointerException error in POM code

Question

Setup Class

public class Setup {
 private static AndroidDriver driver = initializeAppiumServer();
 public static AndroidDriver initializeAppiumServer() {
 if (driver == null || driver.toString().contains("(null)")) {
 DesiredCapabilities desiredCapabilities = new DesiredCapabilities();
 desiredCapabilities.setCapability(MobileCapabilityType.DEVICE_NAME, "HXT7Nwewewe9");
 desiredCapabilities.setCapability(MobileCapabilityType.PLATFORM_NAME, "android");
 desiredCapabilities.setCapability("appPackage", "com.abc.abc");
 desiredCapabilities.setCapability("appActivity",
 "com.abc.abc.ui.activity.SplashActivity");
 desiredCapabilities.setCapability("noReset", true);
 try {
 driver = new AndroidDriver(new URL("http://0.2.0.3:7725/wd/hub"), desiredCapabilities);
 } catch (MalformedURLException e) {
 e.printStackTrace();
 }
 System.out.println("Initializing Appium Server");
 return driver;
 } else {
 return driver;
 }
 }
}

Test class

public class LoginTest {
 private LoginPage loginpage;
 private DashboardPage dashboardPage;
 public LoginTest() {
 loginpage = new LoginPage();
 dashboardPage = new DashboardPage();
 }
 @Given("^Launch app$")
 public void Launchapp() {
 loginpage.launchapp();
 }
@Then("^Get logged in$")
public void Getloggedin() {
 loginpage.Login();
 dashboardPage.navigate(); //calling from Dashboard page
}

LoginPage Class

public class LoginPage{
 private AndroidDriver driver;
 public void launchapp() {
 driver = new Setup().initializeAppiumServer();
 }
 public void Login() {
 driver.findElement(Usernametxt).sendKeys("ABC");
 driver.findElement(Passwordtxt).sendKeys("ABC")
 driver.findElement(Loginbtn).click();
}

DashboardPage Class

 public class DashboardPage {
 private AndroidDriver driver;
 // Where fails
 public void navigate() {
 By settingsbtn = By.id("Button");
 driver.findElement(settingsbtn).click();
 }
 }

When I run I'm getting java.lang.NullPointerException for DashboardPage navigate()function, But all works fine if i add the function to the login page. Is this something to do with the driver? How to solve this?

• João Farias: Can you paste the stacktrace of the NPE?

Answer 1

1. you are not passing any driver instance to the Dashboard DashboardPage

2. You are trying to access local variable 'driver' which is not initialized yet

Solution:

Add :

 public void launchapp() {
 driver = new Setup().initializeAppiumServer();
 }

Or pass the already initialized driver to the dashboard:

in your dashboard class also or pass the driver object to dashboard class before trying to find element.

Correct approach

Test Class::

public class LoginTest {
 private LoginPage loginpage;
 private DashboardPage dashboardPage;
 private AndroidDriver driver;
 public LoginTest() {
 driver= Setup().initializeAppiumServer()
 loginpage = new LoginPage(driver);
 dashboardPage = new DashboardPage(driver);
 }
 @Given("^Launch app$")
 public void Launchapp() {
 loginpage.launchapp();
 }
@Then("^Get logged in$")
public void Getloggedin() {
 loginpage.Login();
 dashboardPage.navigate(); //calling from Dashboard page
}

Login Class

public class LoginPage{
 private AndroidDriver driver;
 public LoginPage(driverInst) {
 driver = driverInst;
 }
public void launchapp() {
 driver.launchApp();
}
 public void Login() {
 driver.findElement(Usernametxt).sendKeys("ABC");
 driver.findElement(Passwordtxt).sendKeys("ABC")
 driver.findElement(Loginbtn).click();
}

Dashboard class:

 public class DashboardPage {
 private AndroidDriver driver;
 public DashboardPage(driverInst) {
 driver = driverInst;
 }
 // Where fails
 public void navigate() {
 By settingsbtn = By.id("Button");
 driver.findElement(settingsbtn).click();
 }
 }