Question

If I have a variable

LinkedList list

and repeatedly do the following to extract the tail of ‘list’

// Some operation that adds elements to 'list'
// max_size = some constant
list = (LinkedList) list.subList(list.size()-max_size, list.size());

do I end up with a lot of references to the ‘previous’ list?

So basically what I’m trying to do here is to remove an initial segment of the list.

Is there a better way to remove an initial segment of a LinkedList? I think the data structure of LinkedList should allow linear time (linear in the size of the initial segment to be removed) operation.

Answer 1

That code will simply fail – the returned sublist is not a LinkedList<T>. Sample program:

import java.util.LinkedList;

public class Test {
    public static void main(String[] args) {
        LinkedList<String> list = new LinkedList<String>();
        list.add("x");
        list.add("y");
        list = (LinkedList<String>) list.subList(1, 2);
    }
}

Output:

Exception in thread "main" java.lang.ClassCastException: java.util.SubList
    cannot be cast to java.util.LinkedList
    at Test.main(Test.java:8)

It sounds like you should just be calling removeFirst as many times as you need to:

while (list.size() > maxSize) {
    list.removeFirst();
}