Complex stream with multiple findElements and conditions

Question

I have a List<RowObject> for which I need to convert to WebElements , then for each row find specific column, then find specific attribute and in the end - getText() How to do it in streams? It doesn't accept what I'm trying to do:

List<WebElement> list1 = getsomeRowstList().stream()
                .map(TableRow::getWebElement)
                .collect(Collectors.toList()); //it works OK

then

List<String> list2 = list1.stream()
                .filter(a -> a.findElements(By.cssSelector("locator-for-specific-column-with-parameter"))
                        .stream().filter(m -> m.findElements(By.cssSelector("row-index-locator"))).map(WebElement::getText)
                        .collect(Collectors.toList())); 

It does not accept it and underlines the second findElements saying:

Bad return type in lambda expression: List<WebElement> cannot be converted to boolean

I'm quite new to streams

Answer 1

filter() is an intermediate operation, so stream().filter(); does not work (see the formatting below).

List<WebElements> list2 = list1.stream()
        .filter(
                a -> a.findElements(By.cssSelector("locator-for-specific-column-with-parameter"))
                .stream().filter(m -> m.findElements(By.cssSelector("row-index-locator"))).map(WebElement::getText)
                .collect(Collectors.toList())
                ); 

Your return type is List<String> list2 . I recommend you to do the filtering first (gives you the specific WebElement ), then convert it with map ( WebElement::getText ).

I haven't tested but it should be something like this:

List<String> list2 = list1.stream()
        .filter(a -> a.findElements(By.cssSelector("locator-for-specific-column-with-parameter")).stream()
                .filter(m -> m.findElements(By.cssSelector("row-index-locator"))))
        .map(WebElement::getText).collect(Collectors.toList());