Example
For simple alert:
Alert simpleAlert = driver.switchTo().alert();
String alertText = simpleAlert.getText();
System.out.println("Alert text is " + alertText);
simpleAlert.accept();
For Prompt alert:
Alert promptAlert = driver.switchTo().alert();
String alertText = promptAlert.getText();
System.out.println("Alert text is " + alertText);
//Send some text to the alert
promptAlert.sendKeys("Accepting the alert");
Thread.sleep(4000); //This sleep is not necessary, just for demonstration
promptAlert.accept();
For Confirmation alert:
Alert confirmationAlert = driver.switchTo().alert();
String alertText = confirmationAlert.getText();
System.out.println("Alert text is " + alertText);
confirmationAlert.accept();
Another way you can do this, is wrap your code inside a try-catch:
try{
// Your logic here.
} catch(UnhandledAlertException e){
Alert alert = driver.switchTo().alert();
alert.accept();
}
// Continue.
