I am new to this java Selenium.
I have 2 classes. 1 parent and 1 child.
I have some methods in the parent class.
I pass 2 of them to the child class.
The problem is only 1 method (from the parent) executes and the 2nd failed.
can you help me to understand why I am getting the error and how to resolve it please :
"java.lang.NullPointerException"
Parent class :
public class SignUp {
public WebDriver driver;
    public void go(WebDriver driver)
    {
    driver.findElement(By.id("id_sign_up")).click();
    }
        @Test
        public void signup(WebDriver driver)
        
        {
            driver.findElement(By.linkText("I’m an advertiser")).click();
        }
        
            public void FormSign (WebDriver driver)
            
            {
                driver.findElement(By.xpath("//span[@css='1']")).sendKeys("Miron");
            }
        
}
Child class :
public class OpenBrowser extends SignUp{
@Test
public void Start() throws InterruptedException
{   
    
    System.setProperty("webdriver.chrome.driver", "C:\\Program Files\\Selenium\\chromedriver.exe");
    WebDriver driver = new ChromeDriver();
    driver.get("https://account.admitad.com/en/sign_in/");
    SignUp sg = new SignUp();
    sg.go(driver);
    //sg.signup(driver);
    
}
@Test
public void miron ()
{
    SignUp mi = new SignUp();
    mi.signup(driver);
}
Can someone please help me? Thanks in advance
 
     
    