What is the cost of ContainsAll in Java?

arrays, interface, java, list

Solution

- first, it iterates each element of the supplied collection

- then it iterates all elements of the list and compares the current element with them using `.equals(..)` (Note: this is about lists, as you specified in the question. Other collections behave differently)

So it's O(n*m), where n and m are the sizes of both collections.

public boolean containsAll(Collection<?> c) {
    Iterator<?> e = c.iterator();
    while (e.hasNext())
        if (!contains(e.next()))
        return false;
    return true;
}

Problem

Original source