Handle javascript alert in iframe using Selenium 2 - selenium

Question

I trying to practice handling Javascript alert. I want to accept alert ,which comes out of iframe in w3school website.
WebDriver driver = new ChromeDriver();
driver.get("http://www.w3schools.com/js/tryit.asp?filename=tryjs_alert");
driver.switchTo().frame("iframeResult");
driver.findElement(By.xpath("/html/body/button")).click();
WebElement editable = driver.switchTo().activeElement();
editable.sendKeys("enter");
//handle pop alert
String mainPage = driver.getWindowHandle();
Alert alt = driver.switchTo().alert();
alt.accept();
driver.switchTo().window(mainPage);
I am just getting alert box and then below error. I am not able to accept it.
Exception in thread "main" org.openqa.selenium.UnhandledAlertException: unexpected alert open: {Alert text : I am an alert box!}

Answer 1

You have all the right code. The error comes when you try to do something other than handle the alert once the alert is up. You have some extraneous code that isn't needed to handle the alert. I've removed it in the code below. You can add things back but you will need to add them before or after launching the alert and handling it.
WebDriver driver = new ChromeDriver();
driver.get("http://www.w3schools.com/js/tryit.asp?filename=tryjs_alert");
driver.switchTo().frame("iframeResult");
driver.findElement(By.xpath("/html/body/button")).click(); // this launches the alert
driver.switchTo().alert().accept(); // this one line accepts the alert
driver.switchTo().defaultContent(); // you will probably need to switch back out of the IFRAME at some point to access the main page again so I added this line
One thing that I would strongly suggest for you is to read some guides on debugging in the IDE of your choice. If you learned how to debug your code, you could walk through it and more likely see where the issue was and fix it.