How to perform mouseover function in Selenium WebDriver using Java?

Its not really possible to perform a 'mouse hover' action, instead you need to chain all of the actions that you want to achieve in one go. So move to the element that reveals the others, then during the same chain, move to the now revealed element and click on it.

When using Action Chains you have to remember to 'do it like a user would'.

Actions action = new Actions(webdriver);
WebElement we = webdriver.findElement(By.xpath("html/body/div[13]/ul/li[4]/a"));
action.moveToElement(we).moveToElement(webdriver.findElement(By.xpath("/expression-here"))).click().build().perform();

None of these answers work when trying to do the following:

1. Hover over a menu item.
2. Find the hidden element that is ONLY available after the hover.
3. Click the sub-menu item.

If you insert a 'perform' command after the moveToElement, it moves to the element, and the sub-menu item shows for a brief period, but that is not a hover. The hidden element immediately disappears before it can be found resulting in a ElementNotFoundException. I tried two things:

Actions builder = new Actions(driver);
builder.moveToElement(hoverElement).perform();
builder.moveToElement(clickElement).click().perform();

This did not work for me. The following worked for me:

Actions builder = new Actions(driver);
builder.moveToElement(hoverElement).perform();
By locator = By.id("clickElementID");
driver.click(locator);

Using the Actions to hover and the standard WebDriver click, I could hover and then click.

Based on this blog post I was able to trigger hovering using the following code with Selenium 2 Webdriver:

String javaScript = "var evObj = document.createEvent('MouseEvents');" +
                    "evObj.initMouseEvent(\"mouseover\",true, false, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);" +
                    "arguments[0].dispatchEvent(evObj);";


((JavascriptExecutor)driver).executeScript(javaScript, webElement);