Selenium – Find element at other element level

I have following piece of code to read value from one field:

private final String dataRowXpath = "*//div[@ref='eCenterContainer']//div[@role='row']";
private final String nbrCellXpath = "//div[@col-id='tradeCount']//span"

List<WebElement> dataRows = driver.findElements(By.xpath(dataRowXpath));

        WebElement row = dataRows
                .stream()
                .filter(row -> row.getAttribute("row-id").equals("USD"))
                .findFirst()
                .get();

String text = row.findElement(By.xpath(nbrCellXpath)).getText()

In this case I receive an empty string.

If I do it in this way with long xpath it reads correct value:

String xpath = "*//div[@ref='eCenterContainer']//div[@role='row' and @row-id='USD']" + nbrOfCellXpath;
WebElement element = driver.findElement(By.xpath(xpath));
String text = element.getText();

So my question is why using findElement at WebElement row doesn’t work.

I’d like to do it this way because I need to read more values from specific row elements so it would be better to have possibility to separate needed row first.

Answer

In order to find element inside element with XPath locator the XPath locator should start with a dot ..
So, in order to locate a cell inside a row with

String text = row.findElement(By.xpath(nbrCellXpath)).getText()

please try defining the nbrCellXpath XPath expression as

".//div[@col-id='tradeCount']//span"