Selenium Chrome WebDriver - fail to get cells list - selenium

Question

I have the following code:
WebElement table = a_chromeWebDriver.findElement(By.className("stats-table"));
List<WebElement> allRows = table.findElements(By.tagName("tr"));
system.out.println(allRows.size());
for (WebElement row : allRows) {
ArrayList<WebElement> cells = (ArrayList<WebElement>) row.findElements(By.tagName("td"));
...
I am executing this code on a similar html like this one:
<table id="table-type-1" class="stats-table stats-main table-1">
<thead>
<tr class="main">
<th class="aaaa" data-type="rank" title="Rank">
</th>
A number of headers here...
</tr>
</thead>
<tbody title="">
<tr bla bla bla>
<td class="bla bla bla" title="bla bla bla>1.</td>
<td class="bla bla bla"></td>
<td class="bla bla bla">36</td>
<td class="bla bla bla">28</td>
<td class="bla bla bla">3</td>
</tr>
<td class="bla bla bla" title="bla bla bla>1.</td>
<td class="bla bla bla"></td>
<td class="bla bla bla">45</td>
<td class="bla bla bla">fnf</td>
<td class="bla bla bla">kfkfk</td>
</tr>
.
.
.
allRows size gives me a correct number of rows.
For some reason, I get cells = null.
I have also tried By.xpath("td") but with no use.

Answer 1

when you loop using this code :
for (WebElement row : allRows) {
ArrayList<WebElement> cells = (ArrayList<WebElement>) row.findElements(By.tagName("td"));
System.out.println("CellCount " + cells.size());
}
You will see that you get output as :
CellCount 0
CellCount 4
CellCount 4
That is because the first row that is picked up by your code is from <thead> section where there are no <td> elements rest it works fine; so you have to make exception for first <tr>
you can do that by changing your allRows element to following:
List<WebElement> allRows = table.findElements(By.xpath("tbody//tr"));

Answer 2

First, find all the rows and then iterate over them:
List<WebElement> allRows = driver.findElements(By.cssSelector("#table-type-1 > tbody > tr"));
for(WebElement row : allRows){
List<WebElement> cells = row.findElements(By.tagName("td"));
System.out.println("Cell count: " + cells.size());//cell count for a row
}

Answer 3

A HTML <table> consists of 3 sections: <thead>, <tbody> and <tfoot>.
Usually you will see only <thead> and <tbody>.
The correct way is to first identify each of these sections and then work your way through their child elements.
// Get the table
WebElement table = a_chromeWebDriver.findElement(By.id("table-type-1"));
// Get the thead in table
WebElement thead = table.findElement(By.tagName("thead"));
// Get the tbody in table
WebElement tbody = table.findElement(By.tagName("tbody"));
// Get all headers in thead
List<WebElement> allHeaders = thead.findElements(By.tagName("th"));
// Get all rows in tbody
List<WebElement> allRows = tbody.findElements(By.tagName("tr"));
// Get all cells for each row in allRows
for(WebElement row : allRows) {
List<WebElement> allCells = row.findElements(By.tagName("td"));
int rowNum = allRows.indexOf(row) + 1;
System.out.println("Row no. " + rowNum + " has " + allCells.size() +" cells.");
}