org.testng.TestNGException: An error occurred while instantiating classAn error occurred while instantiating class, Check to make sure it can be instantiated

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Hi ,
I am new to Appium, I have app which is fully developed using web view.
After launching the app, i am switching the context to the web view of the app.
class Baseclass{
public static UiAutomator2Options options;
public static AndroidDriver driver;
driver = new AndroidDriver(new URL(url),options);
}

class Test extends Baseclass{

@FindBy(how=How.XPATH,using="")
WebElement loginscreen;

public UserLoginPage(AndroidDriver driver) {
	
	this.driver= driver;
	PageFactory.initElements(this.driver, this);

} }

when i try to instantiating page elements in extended class, page elements are not getting instantiating . and throwing error
"
org.testng.TestNGException: An error occurred while instantiating classAn error occurred while instantiating class, Check to make sure it can be instantiated

can u please, help me in resolving the page file instantiation.