Below method will return true if the alert got displayed:
public boolean isAlertPresent() { boolean presentFlag = false; try { // Check the presence of alert Alert alert = driver.switchTo().alert(); // Alert present; set the flag presentFlag = true; // if present consume the alert alert.accept(); } catch (NoAlertPresentException ex) { // Alert not present ex.printStackTrace(); } return presentFlag; }Note - Thank you Ganesh S for asking this query.