JavascriptExecutor exe = (JavascriptExecutor) driver;
 Integer numberOfFrames = Integer.parseInt(exe.executeScript("return window.length").toString());
 System.out.println("Number of iframes on the page are " + numberOfFrames);

 //By finding all the web elements using iframe tag
 List<WebElement> iframeElements = driver.findElements(By.tagName("iframe"));
 System.out.println("The total number of iframes are " + iframeElements.size());