Error while executing Selenium script - java.lang.NullPointerException - TestNG - selenium

Question

I'm trying to run a script via testNG. But getting java.lang.NullPointerException. I have put in the driver initialisation code in BeforeMethod and rest of the code under Test. Please let me know what's wrong in my script due which Im getting the error.Thanks in Advance.
My Script:
public class NewTest {
WebDriver driver = null;
#BeforeMethod
public void beforeMethod() {
System.setProperty("webdriver.chrome.driver", Constants.Chrome_Driver);
WebDriver driver = new ChromeDriver();
driver.manage().window().maximize();
driver.manage().timeouts().implicitlyWait(30, TimeUnit.SECONDS);
driver.get("http://" + Constants.auth_Username + ":" + Constants.auth_Password + "#" + Constants.URL);
}
#Test
public void f() throws InterruptedException {
actions.Admin_Login.txbx_aUsername(driver).sendKeys(Constants.aUsername);
actions.Admin_Login.txbx_aPassword(driver).sendKeys(Constants.aPassword);
actions.Admin_Login.btn_login(driver).click();
actions.create(driver).click();
Actions action = new Actions(driver);
action.moveToElement(actions.create.list(driver)).build().perform();
actions.create_list.list_category(driver).click();
actions.create_list.list_ceate_category(driver).click();
actions.create_list.txtbx_Cat_tile(driver).sendKeys(Constants.list_title);
actions.create_list.btn_Cat_Save(driver).click();
System.out.println("List Created Successfully");
}
}
I am using PageObjects to get the data. This script is running fine without testNG. But when I convert the test into testNG and execute, it throws error.
Error I am facing:
java.lang.NullPointerException
at actions.Admin_Login.txbx_aUsername(Admin_Login.java:13)
at testScripts.NewTest.f(NewTest.java:43)
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:498)
at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:124)
at org.testng.internal.Invoker.invokeMethod(Invoker.java:580)
at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:716)
at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:988)
at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:125)
at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:109)
at org.testng.TestRunner.privateRun(TestRunner.java:648)
at org.testng.TestRunner.run(TestRunner.java:505)
at org.testng.SuiteRunner.runTest(SuiteRunner.java:455)
at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:450)
at org.testng.SuiteRunner.privateRun(SuiteRunner.java:415)
at org.testng.SuiteRunner.run(SuiteRunner.java:364)
at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:84)
at org.testng.TestNG.runSuitesSequentially(TestNG.java:1208)
at org.testng.TestNG.runSuitesLocally(TestNG.java:1137)
at org.testng.TestNG.runSuites(TestNG.java:1049)
at org.testng.TestNG.run(TestNG.java:1017)
at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:114)
at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:251)
at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:77)
Constants Class :
public class Constants {
public static final String URL_Shika = "url";
public static final String list_Title = "Test";
public static final String aUsername = "Test";
public static final String aPassword = "abcd123";
public static final String uUsername = "Test01";
public static final String uPassword = "abcd123";
public static final String vUsername = "test321";
public static final String vPassword = "abcd123";
public static final String auth_Username = "admin";
public static final String auth_Password = "admin#123";
public static final String FF_Driver = "/path/geckodriver";
public static final String Chrome_Driver = "/path/chromedriver";
}
Action Class:
public class Admin_Login {
private static WebElement element = null;
public static WebElement txbx_aUsername (WebDriver driver) {
element = driver.findElement(By.id("username"));
return element;
}
public static WebElement txbx_aPassword (WebDriver driver) {
element = driver.findElement(By.id("password"));
return element;
}
}

Answer 1

The driver object you are initialising in #BeforeMethod is not visible in your test method. Try following:
public class NewTest {
WebDriver driver = null;
#BeforeMethod
public void beforeMethod() {
System.setProperty("webdriver.chrome.driver", Constants.Chrome_Driver);
//Pay close attention this below line. Notice how we are not creating a new WebDriver variable
//but we are just initialising the class level data member here
driver = new ChromeDriver();
driver.manage().window().maximize();
driver.manage().timeouts().implicitlyWait(30, TimeUnit.SECONDS);
driver.get("http://" + Constants.auth_Username + ":" + Constants.auth_Password + "#" + Constants.URL);
}
#Test
public void f() throws InterruptedException {
Admin_Login.txbx_aUsername(driver).sendKeys(Constants.aUsername);
Admin_Login.txbx_aPassword(driver).sendKeys(Constants.aPassword);
Admin_Login.btn_login(driver).click();
actions.create(driver).click();
Actions action = new Actions(driver);
action.moveToElement(actions.create.list(driver)).build().perform();
//Create a Course Category
actions.create_list.list_category(driver).click();
actions.create_list.list_ceate_category(driver).click();
actions.create_list.txtbx_Cat_tile(driver).sendKeys(Constants.list_title);
actions.create_list.btn_Cat_Save(driver).click();
System.out.println("List Created Successfully");
}
}
Please try to wait for the text box to appear, before entering any data using following code:
public static WebElement txbx_aUsername (WebDriver driver) {
WebDriverWait w = new WebDriverWait(driver, 30);
w.until(ExpectedConditions.visibilityOfElementLocated(By.id("username")));
return driver.findElement(By.id("username"));
}
Let me know, if you still face any issue.