how to switch to popup window without window id

driver.switchTo().window(windowName), here the 'windowName' represents the window id, right? if so, then how to switch to popup window without window id? Thanks in advance!

Maybe this part of documentation could help you to solve this issue.

for
(String handle : driver.getWindowHandles())


{


driver.switchTo().window(handle);


String
title = driver.getTitle();


if
(title.equals("Popup Page"))


break;


}