How to close a dialog box using Selenium WebDriver

There might be places, when you click on an object a dialog will pop up asking your conformation. How to close those kind of alert messages?

The below code help you to close any such alert boxes.

import org.openqa.selenium.Alert;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
public class PopupDialog
{
 public static void main(String[] args)
 {
  WebDriver driver=new FirefoxDriver();
  driver.get("http://www.agoda.com/?ymsg=1&tick=634955861691");
 
  Alert alt=driver.switchTo().alert();
  alt.accept();
 }
}