What is complexity of size() for TreeSet portion view in Java

Question

I\'m wondering what is the time complexity of size() for portion view of TreeSet.

Let say I\'m adding random numbers to set (and I do not care about dup

Answer 1

Looks like complexity of size () is O(N), because it may call TreeMap.NavigableSubMap.EntrySetView.size () which is implemented like this (Oracle JDK 1.7.0_13):

public int size() {
    if (fromStart && toEnd)
        return m.size();
    if (size == -1 || sizeModCount != m.modCount) {
        sizeModCount = m.modCount;
        size = 0;
        Iterator i = iterator();
        while (i.hasNext()) {
            size++;
            i.next();
        }
    }
    return size;
}