How to create a sublist from List<Object> in apache velocity template .vm - velocity

Question

I am new to apache velocity, I want to create a subList Object from the List Objects which are coming from some service call in .vm file.
We need to render the list based on some logic in parts, for that we want to create sublist from list.
$table.getBooks() //contains all the Books objects
Below is the sample code which I tried but it did not work.
#set($segregatedList = [])
#set($size = $table.getLineItems().size())
#foreach($index in [0..$size-1])
#set($value = $index + 4)
#set($minimum = $math.min($nItems,$value))
$segregatedList.add($table.getBooks().subList($index,$minimum)))
$index += 4
#end
I executed the code, while rendering $segregatedList is coming as null.
I verified $table.getBooks() contains the Objects as when I am passing this,Objects are getting rendered successfully.
Can someone please tell what I am doing wrong or how can I create a sublist ?

Answer 1

First you are increment index with 4 and can cause an IndexOutOfBoundsException, so need to change until size-5 (and therefore remove math minimum check)
Second you are adding single Element instead of all Elements using addAll
Third your size check if on wrong parameter - should be on relevant $table.getBooks()
And last make sure your list have more than 5 elements
#set($segregatedList = [])
#set($size = $table.getBooks().size())
#foreach($index in [0..$size-5])
#set($value = $index + 4)
$segregatedList.addAll($table.getBooks().subList($index, $value)))
$index += 4
#end