How to Loop Through List of Webelements and Select One Webelement With a Condition

How can I loop through list of WebElements and select one WebElement with a condition?

Use findElement-S method as shown below.

    for (WebElement element : elements) {
        List<WebElement> mightHaveSomeDiv = element.findElements(By.cssSelector("someDiv"));

        if (mightHaveSomeDiv.size() > 0) {
            //Can iterate the list if you expect more than one div of type someDiv.
            String myText = mightHaveSomeDiv.get(0).getText();
            if (myText.contains("Ooga Booga")) {
                return element;
            }
        }
    }

how to loop through List<WebElement>

You could do something like...

List<WebElement> links = driver.find elements(By.cssSelector('#tblPriorEventsBody td a'));

Iterator<WebElement> iter = links.iterator();

while(iter.hasNext()) {
    WebElement we = iter.next();

    if (we.text.equals("whatever") {
        we.click;
    // do something in else perhaps
    }
}

Add Webelement text into list by iterating each element using for loop

Not sure what is ActualAdFormat_List in your code.

Also there's no need to have parenthesis in xpath, remove them as well.

Please define a list of string like this :

List<String> ActualAdFormat_List = new ArrayList<String>();

and use it like this :

List<WebElement> ActualAdFormats_Elements = driver.findElements(By.xpath("//h4[text()='Select Ad Format']/..//strong"));
for(WebElement AdFormat : ActualAdFormats_Elements) {
    ActualAdFormat_List.add(AdFormat.getText());
        }

Make sure that,

//h4[text()='Select Ad Format']/..//strong

represent all 5 web elements in HTMLDOM.

Steps to check:

Press F12 in Chrome -> go to element section -> do a CTRL + F -> then paste the xpath and see, if your desired element is getting highlighted with 1/1 matching node.

For loop for Checking list of items in Selenium WebDriver

@Saifur has explained nicely regarding the issue. So, I will just put the code that will see you through

List <WebElement> listofItems = wd.findElements(By.xpath("//*[starts-with(@id,'result_')]//div//div[1]//div//a//img"));
WebDriverWait wait = new WebDriverWait(wd, 20); //Wait time of 20 seconds

for (int i=1; i<=listofItems.size(); i++)
{ 
    /*Getting the list of items again so that when the page is
     navigated back to, then the list of items will be refreshed
     again */ 
    listofItems = wd.findElements(By.xpath("//*[starts-with(@id,'result_')]//div//div[1]//div//a//img"));

    //Waiting for the element to be visible
    //Used (i-1) because the list's item start with 0th index, like in an array
    wait.until(ExpectedConditions.visibilityOf(listofItems.get(i-1)));

    //Clicking on the first element 
    listofItems.get(i-1).click();
    wd.manage().timeouts().implicitlyWait(30, TimeUnit.SECONDS);
    System.out.print(i + " element clicked\t--");
    System.out.println("pass");
    wd.navigate().back(); 
}

So, above I have just tweaked your code a bit and have the relevant comments where changes are made and why. Hope this works out for you. :)

Clicking all elements found in List<WebElement>

Make sure elements you try to click is visible. If you don't care about visibility click with javascipt:

JavascriptExecutor js = (JavascriptExecutor) driver;
WebDriverWait wait = new WebDriverWait(driver, 5);

List<WebElement> elements = driver.findElements(By.className("needToClick"));
elements.forEach(e -> {
    js.executeScript("arguments[0].click();", e);
    wait.until(ExpectedConditions.attributeToBe(e,"class", "dontNeedToClick"));
    //if element have not only dontNeedToClick class use attributeContains
    //wait.until(ExpectedConditions.attributeContains(e,"class", "dontNeedToClick"));
});

Check if you can click one element and class changes:

driver.findElement(By.className("needToClick")).click();

if not try xpath:

driver.findElement(By.xpath("//a[i[@class='needToClick']]"));
//or
driver.findElement(By.xpath("//a[i[contains(@class,'needToClick')]]"));

Finding text of all WebElements that match a xpath using only one List

this should work for you:

final List<String> texts = webDriver.findElements(By.xpath("...")).stream()
                                            .map(WebElement::getText)
                                            .collect(toList());