How to check if a popup window is open or not using Selenium WebDriver in Java

If it's a native, browser alert (= a popup) you can do the following:

try{    driver.switchTo().alert();    // If it reaches here, it found a popup} catch(NoALertPresentException e){}

What it looks like you're actually dealing with is an iframe which you can do the following after getting the attribute value of the "iframe" attribute:

driver.switchTo.frame("ValueOfIframe");// Treat as normal webpage. Now in iframe scopedriver.switchTo.defaultContent(); // To return back to normal page scope

String mwh=driver.getWindowHandle();

Now try to open the popup window by performing some action:

driver.findElement(By.xpath("")).click();Set s=driver.getWindowHandles(); //this method will gives you the handles of all opened windowsIterator ite=s.iterator();while(ite.hasNext()){    String popupHandle=ite.next().toString();    if(!popupHandle.contains(mwh))    {        driver.switchTo().window(popupHandle);        /**/here you can perform operation in pop-up window**        //After finished your operation in pop-up just select the main window again        driver.switchTo().window(mwh);    }}