Getting selenium support pagefactory for nullpointerexception

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Java

testing

automation

selenium

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I am creating page object model plus data driver framework.
I am writing Testcase for logIn but getting pagefactory nullpointerexception.
1. How I can initialise  driver in order to avoid this error in testbase and call initialize method in AppTest.java?
2. Again How I can write code to call Sccreenshotpage class in my test script i have given code below for Sccreenshotpage class.

FAILED: Log("s@gmail.com", "sw45") java.lang.NullPointerException at org.openqa.selenium.support.pagefactory.DefaultElementLocator.findElement(DefaultElementLocator.java:69)

TestBase.java class

import java.io.IOException;
import java.util.concurrent.TimeUnit;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;

public class TestBase {
	public WebDriver driver;

	public void initialize() throws InterruptedException, IOException {
		System.out.println("Launching browser");
		System.setProperty("webdriver.chrome.driver",
				"C:\\Users\\data\\chromedriver.exe");
		driver = new ChromeDriver();
		driver.manage().window().maximize();
		driver.manage().timeouts().implicitlyWait(20, TimeUnit.SECONDS);
		driver.navigate().to("http://automationpractice.com/index.php?controller=authentication&back=my-account");
		Thread.sleep(6000);
	}
}

Excelreader.java to read data from excel file

import java.io.IOException;
import org.testng.annotations.DataProvider;
import jxl.Cell;
import jxl.Sheet;
import jxl.Workbook;
import jxl.read.biff.BiffException;
import selenium.org.sample.SampleProject.TestBase.TestBase;

public class ExcelReader extends TestBase {
	@DataProvider(name = "testdata")
	public Object[][] readexcel() throws IOException, BiffException {
		File f = new File(
				"C:\\Users\\Data_driven5.xls");
		Workbook w = Workbook.getWorkbook(f);
		Sheet s = w.getSheet("Sheet1");
		int row = s.getRows();
		int colums = s.getColumns();
		String inputdata[][] = new String[row][colums];
		for (int i = 0; i < row; i++) {
			for (int j = 0; j < colums; j++) {
				Cell c = s.getCell(j, i);
				inputdata[i][j] = c.getContents();
				System.out.println(inputdata[i][j]);
			}
		}
		return inputdata;
	}
}

Signin.java This this when I am finding element

public class SignIn extends TestBase {
	@FindBy(xpath = "//*[@id=\"email\"]")
	WebElement email_;

	@FindBy(xpath = "//*[@id=\"passwd\"]")
	WebElement pwd_;

	@FindBy(xpath = "//*[@id=\"SubmitLogin\"]/span")
	WebElement Sign_In;

	// Set user name in textbox
	public void setUserName(String email_1) {
		email_.sendKeys(email_1);
	}

	public void setPwd(String pwd_1) {
		pwd_.sendKeys(pwd_1);
	}

	public void Sign_In_btn() {
		Sign_In.click();
	}
}

AppTest.java Testcase for log in

public class AppTest extends ExcelReader {
	TestBase TB = new TestBase();

	@BeforeTest
	void browserlaunch() throws InterruptedException, IOException

	{
		TB.initialize();
	}

	@Test(dataProvider = "testdata")
	public void LogIn(String email, String pwd) throws IOException, InterruptedException {
		System.out.println("Sign in page1");
		SignIn loginpage = PageFactory.initElements(driver, SignIn.class);
		loginpage.setUserName(email);// email entered
		loginpage.setPwd(pwd);// password entered
		loginpage.Sign_In_btn();
		driver.manage().window().maximize();
// i want to call ScreenshotPage1 here
		try {
			Assert.assertEquals(driver.getTitle(), "My account - My Store");
			System.out.println("Log  IN successfull1");

		} catch (AssertionError E) {
			System.out.println("Log  IN un-successfull" + E);
		}
		Thread.sleep(8000);
		System.out.println("after click");
// I want to call ScreenshotPage1 method here
	}

}

ScreenshotPage.java

import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import ru.yandex.qatools.ashot.AShot;
import ru.yandex.qatools.ashot.Screenshot;
import ru.yandex.qatools.ashot.shooting.ShootingStrategies;
import selenium.org.sample.SampleProject.TestBase.TestBase;

public class ScreenshotPage extends TestBase {
	private WebDriver driver = new ChromeDriver();

	public void ScreenshotPage1() throws InterruptedException, IOException {
		Screenshot fpScreenshot = new AShot().shootingStrategy(ShootingStrategies.viewportPasting(1000))
				.takeScreenshot(driver);
		ImageIO.write(fpScreenshot.getImage(), "PNG", new File("D:/selenium/" + System.currentTimeMillis() + ".png"));
	}
}

What I have tried:

I have tried to execute code above... just I want to know how I can call methods from other class to avoid nullpoinerexception because of driver. and create tastbase class