Understanding WebElement.findElement() and XPATH

I want to use the WebElement.findElement() API to locate a node inside the parent node using XPATH //span[@class='child-class']. I thought this would return the <div> that is inside the parent. However, it is returning the first one it found in the entire DOM tree. Did I use the wrong XPATH?

I have also tried using .//span[@class='child-class'] as the XPATH, but that does return anything.

Thank you.

UPDATE:

given the HTML below, I want to define a locator for the child-title <span> and child-date <span> and locate them using WebElement.findElement() API regardless of the parent being "//a/li[1]" or "//a/li[2]"

<a>
    <li> parent 1
        <div>
            <span class="child-title child-style">title 1</span>
            <span class="child-date child-style"> date 1</span>
            <span class="child-author">author 1</span>
        </div>
    </li>
</a>
<a>
    <li> parent 2
        <div>
            <span class="child-title child-style">title 2</span>
            <span class="child-date child-style"> date 2</span>
            <span class="child-author">author 2</span>
        </div>
    </li>
</a>
<a>
    <li> parent 3
        <div>
            <span class="child-title child-style">title 3</span>
            <span class="child-date child-style"> date 3</span>
            <span class="child-author">author 3</span>
        </div>
    </li>
</a>

I have a WebElement parent2 initialized and located using "//a/li[2]",

WebElement child = parent2.findElement(By.xpath("//span[@class='child-author']")); would give me "author 1"

WebElement child = parent2.findElement(By.xpath("span[@class='child-author']")); would give me NoSuchElementException

There are my 2 comments with your sample code

1 - With your posted HTML, the xpath //a/li[2] is not found (we only have 3 elements with //a/li[1])

2 - Assume that we do have right code, you need to understand the differences between single slash and double slash in Xpath

a/b (single slash): select element that has "tag b" and "stands right after" an element that has "a tag" 

E.g.:

<a>
    <b>
          <d>
               <c>
               </c>
          </d>
    </b>
</a>

AND

a//b (double slash): select element that has "tag b" and is n-level-child an element that has "a tag"

E.g.:

<a>
    <c>
          <d>
               <b>
               </b>
          </d>
    </c>
</a>

So, with your code

<a>
<li> parent 1
    <div>
        <span class="child-title child-style">title 1</span>
        <span class="child-date child-style"> date 1</span>
        <span class="child-author">author 1</span>
    </div>
</li>
</a>

If you want to get Date Info, you should use

WebElement parent = driver.findElement(By.xpath("//a/li"));
WebElement date = parent.findElement(By.xpath("div/span[contains(@class, 'child-date')]"));
WebElement date = parent.findElement(By.xpath("//span[contains(@class, 'child-date')]"));

The code

WebElement date = parent.findElement(By.xpath("span[contains(@class, 'child-date')]"));

Will bring out NoSuchElementException because there is no [span] tag right after [li] tag

Hope help