无法实例化类TestNg.Drivein

Question

package TestNg;


public class Drivein  {

    WebDriver driver=new FirefoxDriver();
    WebDriverWait myWaitVar;
    HSSFWorkbook workbook;
    HSSFSheet sheet;
    HSSFRow cell;

  @BeforeTest

 public void beforeTest()  
{

System.setProperty("webdriver.gecko.driver", "geckodriver.exe");

      FirefoxOptions options = new FirefoxOptions();

     options.setCapability("marionette", false); 

        //Launch the website
      driver.get("http://qa.greenbuds.in/drivein");
      driver.manage().window().maximize();

      myWaitVar= new WebDriverWait(driver, 30);

  }

  @Test(priority=0)

  public void f() throws InterruptedException

  {

         driver.findElement(By.name("username")).sendKeys("admin");
         driver.findElement(By.name("password")).sendKeys("password");
         Thread.sleep(3000);
         driver.findElement(By.xpath("//button[text()='Submit']")).click();
         Thread.sleep(3000);

  }

}