Question

If I need to remove elements in a list, will the following be better than using LinkedList:

int j = 0;
List list = new ArrayList(1000000);
...
// fill in the list code here
...
for (Iterator i = list.listIterator(); i.hasNext(); j++) {
    if (checkCondition) {
        i.remove();
        i = list.listIterator(j);
    }
}

?

LinkedList does “remove and add elements” more effectively than ArrayList, but LinkedList as a doubly-linked list needs more memory, since each element is wrapped as an Entry object. While I need a one-direction List interface, because I’m running over in ascending order of index.

Answer 1

The answer is: it depends on the frequency and distribution of your add and removes. If you have to do only a single remove infrequently, then you might use a linked list. However, the main killer for an ArrayList over a LinkedList is constant time random access. You can’t really do this with a normal linked list (however, look at a skip list for some inspiration..). Instead, if you’re removing elements relative to other elements (where, you need to remove the next element) then you should use a linked list.