How to use InvalidElementStateException class of org.openqa.selenium package

Recently Selenium has launched Selenium 3 and if you are trying to use Firefox latest version then you have to use GeckoDriver:

System.setProperty("webdriver.gecko.driver","G:\\Selenium\\Firefox driver\\geckodriver.exe");
WebDriver driver = new FirefoxDriver();

You can check full documentation from here

In a word, no. It's not possible using the Selenium WebDriver API. This has been discussed ad nauseam in the issue tracker for the project, and the feature will not be added to the API.

For sure you can. We use Selenium a lot as an assistant in getting some datas from websites.

When you have a process involving multiple steps, including opening website, login, choosing 54 parameters and need only 1 human interaction (resolving a captcha, for example), Selenium can automate those boring tasks and let the user concentrate on the one which is important.

What we do here, is to make a Swing dialog with an input field to get what the user want to enter, then the actual form submission is performed by Selenium. You can do the same thing with links, and you can ask the user to select a link to click on, and perform the actual click with webdriver.

The ExplicitWait method of Amith is also a good one. You can focus on what you expect after the user has clicked, and wait until this condition is realized

    Locatable hoverItem = (Locatable) driver.findElement(By.xpath("//li[text()='Reklama w Google']"));
    int y = hoverItem.getCoordinates().getLocationOnScreen().getY();
    ((JavascriptExecutor)driver).executeScript("window.scrollBy(0,"+y+");");

You want to wait until the alert is present before switching to it, similar to your 3rd row. Reference.

EDIT: try:

new WebDriverWait(driver, 60)
        .ignoring(NoAlertPresentException.class)
        .until(ExpectedConditions.alertIsPresent());

Alert al = driver.switchTo().alert();
al.accept();

Please read this Martin Follower's article - Page Object.

A quotation:

Despite the term "page" object, these objects shouldn't usually be built for each page, but rather for the significant elements on a page

Imagine a page which has over of dozen tabs, panels etc, and each one have a few fields, buttons etc. It would be impractical to create a huge class for such a page, it would certainly have 300-500 or more lines of code. Such a class would be very hard to maintain.

It's better (in my opinion) to create several small classes (page objects), each for a specific section of the page, each one containing only a few elements, each no more than 50-100 lines of code. We call these classes page fragments instead of page objects, but the concept is the same.

But it will vary from person to person and everyone may have a different opinion on this topic.

Before you try searching for the elements within the iframe you will have to switch Selenium focus to the iframe.

Try this before searching for the elements within the iframe:

driver.switchTo().frame(driver.findElement(By.name("iFrameTitle")));

It seems you catch an incorrect exception. Try code below:

try {
    WebElement submitbuttonPresence=driver.findElement(By.id("btnOk"));
    submitbuttonPresence.click();
}
catch (org.openqa.selenium.NoSuchElementException e) {
    System.out.println(driver.getTitle());
}

elementToBeClickable is used for checking an element is visible and enabled such that you can click it.

ExpectedConditions.elementToBeClickable returns WebElement if expected condition is true otherwise it will throw TimeoutException, It never returns null.

So if your using ExpectedConditions.elementToBeClickable to find an element which will always gives you the clickable element, so no need to check for null condition, you should try as below :-

WebDriverWait wait = new WebDriverWait(Scenario1Test.driver, 10); 
WebElement element = wait.until(ExpectedConditions.elementToBeClickable(By.xpath("(//div[@id='brandSlider']/div[1]/div/div/div/img)[50]")));
element.click();

As you are saying element.click() passes both on link and label that's doesn't mean element is not clickable, it means returned element clicked but may be there is no event performs on element by click action.

Note:- I'm suggesting you always try first to find elements by id, name, className and other locator. if you faced some difficulty to find then use cssSelector and always give last priority to xpath locator because it is slower than other locator to locate an element.

Hope it helps you..:)