完成所有指令后跳过Selenium webdriver测试，并给出java.lang.NullPointerException错误，我该如何解决？

Question

package defaultTest;

import java.io.FileInputStream;

import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.testng.Assert;
import org.testng.annotations.BeforeClass;
import org.testng.annotations.Test;
import org.testng.annotations.AfterMethod;
import org.testng.annotations.DataProvider;

public class NewTest{
    static WebDriver driver;
    XSSFWorkbook wb;
    XSSFSheet sheet1;
    int numrow;

    @BeforeClass
    public void setUp() {
        driver = new FirefoxDriver();
        //gmail URL
        driver.get("https://accounts.google.com/ServiceLogin?service=mail&continue=https://mail.google.com/mail/");
    }

    @DataProvider(name = "testdata")
    public Object[][] dp() throws Exception {
        Object[][] tabArray = null;
        try {
            FileInputStream fis = new FileInputStream(
                "C:\\Users\\gaurav\\workspace\\Test\\src\\Resources\\LoginDataExcelFile.xlsx");
            wb = new XSSFWorkbook(fis);
            sheet1 = wb.getSheet("TestSheet");

            for (int count = 0; count <= sheet1.getLastRowNum(); count++) {
                XSSFRow row = sheet1.getRow(count);
                //System.out.println("ID: "+row.getCell(0).toString()+"\t password : "+row.getCell(1).toString());
                testLogin(row.getCell(0).toString(), row.getCell(1).toString());
            }
            fis.close();
        } catch (Exception e) {
            System.out.println(e);
        }
        return tabArray;
    }

    @Test(dataProvider = "testdata")
    public void testLogin(String UserName, String Password)throws Exception {

        driver.findElement(By.id("Email")).clear();
        Thread.sleep(2000);
        driver.findElement(By.id("Email")).sendKeys(UserName);
        Thread.sleep(2000);
        driver.findElement(By.id("Passwd")).clear();
        Thread.sleep(2000);
        driver.findElement(By.id("Passwd")).sendKeys(Password);
        Thread.sleep(2000);
        driver.findElement(By.name("signIn")).click();
        Thread.sleep(20000);

        WebElement name = driver
    .findElement(By
            .xpath(".//*[@id=':hw']/div/div"));
        try {
            Assert.assertEquals("COMPOSE", name.getText());//Used some assertion
            System.out.println(name.getText());
        } catch(Exception e) {
            System.out.println(e);
        }
    }

    @AfterMethod
    public void afterMethod() {
        driver.close();
        driver.quit();
    }
}

It's a test application. Before running the test, make sure that the excel file have a loginID and password only without any header.
Issue is, I have just one record in excel file, my above script runs once successfully, but when the for loop runs again, it finds no record in excel, and my test gets skipped, and hence the other test get failed.

> [TestNG] Running:  
> C:\Users\gaurav\AppData\Local\Temp\testng-eclipse-1831957551\testng-customsuite.xml
> 
> COMPOSE
> 
> SKIPPED: testLogin java.lang.NullPointerException     at
> org.testng.internal.MethodInvocationHelper.invokeDataProvider(MethodInvocationHelper.java:149)
>   at
> org.testng.internal.Parameters.handleParameters(Parameters.java:429)
>   at org.testng.internal.Invoker.handleParameters(Invoker.java:1383)
>   at org.testng.internal.Invoker.createParameters(Invoker.java:1075)
>   at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1180)
>   at
> org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:127)
>   at
> org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:111)
>   at org.testng.TestRunner.privateRun(TestRunner.java:767)    at
> org.testng.TestRunner.run(TestRunner.java:617)    at
> org.testng.SuiteRunner.runTest(SuiteRunner.java:334)  at
> org.testng.SuiteRunner.runSequentially(SuiteRunner.java:329)  at
> org.testng.SuiteRunner.privateRun(SuiteRunner.java:291)   at
> org.testng.SuiteRunner.run(SuiteRunner.java:240)  at
> org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)  at
> org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:86)   at
> org.testng.TestNG.runSuitesSequentially(TestNG.java:1224)     at
> org.testng.TestNG.runSuitesLocally(TestNG.java:1149)  at
> org.testng.TestNG.run(TestNG.java:1057)   at
> org.testng.remote.RemoteTestNG.run(RemoteTestNG.java:111)     at
> org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:204)  at
> org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:175)
> 
> 
> ===============================================
>     Default test
>     Tests run: 1, Failures: 0, Skips: 1
> ===============================================

Answer 1

Change @AfterMethod to @AterClass or change @BeforeClass to @BeforeMethod

And on a side note, I would change --> static WebDriver driver; to private WebDriver driver;

Answer 2

You data provider returns null value. You need to write code to pass values through tabArray.

Answer 3

You need to put data in your tabArray after reading the excel. There is no need for you to call the testLogin method in the dataprovider method, which would defeat the entire purpose of using the DataProvider.

Read a bit about dataprovider @ http://testng.org/doc/documentation-main.html#parameters-dataproviders

In your for loop, replace the call to your testLogin method with putting data in your tabArray. eg.

tabArray[count] =  new Object[]{row.getCell(0).toString(), row.getCell(1).toString()};