Selenium:How to perform mouse over in selenium web driver

package New;

import java.util.concurrent.TimeUnit;

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.interactions.Actions;
import org.openqa.selenium.support.ui.WebDriverWait;
import org.testng.annotations.Test;
import org.testng.annotations.BeforeClass;
import org.testng.annotations.AfterClass;

public class Mouse_Over {
    WebDriver driver;
  @Test
  public void mouesover() throws InterruptedException {
      driver.get("http://www.flipkart.com/");
    // WebElement element= driver.findElement(By.xpath("//span[text()='Electronics']"));
      WebElement element= driver.findElement(By.xpath("//a[@data-tracking-id='electronics']"));
     Actions a =new Actions(driver);
     a.moveToElement(element).build().perform();
    // a.clickAndHold(element);
     Thread.sleep(5000);
     
     //WebDriverWait wd=new WebDriverWait(driver, 30);
  }
  @BeforeClass
  public void beforeClass() {
      driver=new FirefoxDriver();
      driver.manage().window().maximize();
      driver.manage().timeouts().implicitlyWait(30,TimeUnit.SECONDS);
     
  }

  @AfterClass
  public void afterClass() {
      driver.quit();
     
  }

}