Selenium webdriver Selenium webdriver-无法单击子菜单-amazon.in

我正试图点击亚马逊网站中的submneu 我可以展开主菜单。但不能点击子菜单。我尝试了两种方法。但它显示出错误

邮件类别html代码：

<li class="nav_pop_li nav_cat nav_divider_before" id="nav_cat_2">Books</li>

方法2

driver.get("http://amazon.in");
        driver.manage().window().maximize();
    //locate the menu to hover over using its xpath
            WebElement menu = driver.findElement(By.xpath("//li[@id='nav_cat_2']"));

            //Initiate mouse action using Actions class
            Actions builder = new Actions(driver);    

            // move the mouse to the earlier identified menu option
            builder.moveToElement(menu).build().perform();

            // wait for max of 5 seconds before proceeding. This allows sub menu appears properly before trying to click on it
            WebDriverWait wait = new WebDriverWait(driver, 5); 
            wait.until(ExpectedConditions.presenceOfElementLocated(By.xpath("//a[@class='nav_a nav_item']")));  // until this submenu is found

            //identify menu option from the resulting menu display and click
            WebElement menuOption = driver.findElement(By.xpath("//a[@class='nav_a nav_item']"));
            menuOption.click();

请告诉我为什么它不工作？

在方法1中，我想在悬停时出现了问题。我必须说，它只是点击了“主要类别”元素

在方法2“中，“主类别”的悬停正确发生。唯一的问题是选择点击“子类别”的xpath。xpath实际上与多个元素相关联。因此，代码失败了

只需更换方法2中的以下代码，即可工作：-

wait.until(ExpectedConditions.presenceOfElementLocated(By.xpath("//a[@class='nav_a nav_item' and .=\"All Books\"]")));

及

注意：-在上面，我使用了所有书籍作为要单击的文本
（此文本必须与网页中显示的内容完全匹配。）
类似地，您可以用其他文本（如“畅销书、新版本和预购书等”）替换所有书籍

driver.get("http://amazon.in");
        driver.manage().window().maximize();
    //locate the menu to hover over using its xpath
            WebElement menu = driver.findElement(By.xpath("//li[@id='nav_cat_2']"));

            //Initiate mouse action using Actions class
            Actions builder = new Actions(driver);    

            // move the mouse to the earlier identified menu option
            builder.moveToElement(menu).build().perform();

            // wait for max of 5 seconds before proceeding. This allows sub menu appears properly before trying to click on it
            WebDriverWait wait = new WebDriverWait(driver, 5); 
            wait.until(ExpectedConditions.presenceOfElementLocated(By.xpath("//a[@class='nav_a nav_item']")));  // until this submenu is found

            //identify menu option from the resulting menu display and click
            WebElement menuOption = driver.findElement(By.xpath("//a[@class='nav_a nav_item']"));
            menuOption.click();

wait.until(ExpectedConditions.presenceOfElementLocated(By.xpath("//a[@class='nav_a nav_item' and .=\"All Books\"]")));

WebElement menuOption = driver.findElement(By.xpath("//a[@class='nav_a nav_item' and .=\"All Books\"]"));