Time complexity of TreeMap operations- subMap, headMap, tailMap

Question

Does anyone know the time complexity of the operations of TreeMap like - subMap, headMap. tailMap.

The time complexity of operations like get, put is O(logn). But th

Answer 1

I was able to browse the source of TreeMap to get the detailed implementation.

If you go in detail with the source code as to how they are actually getting the subMap its something like this...

If you see the size method of NavigableSubMap

  public int size() {
        return (fromStart && toEnd) ? m.size() : entrySet().size();
    }

The entrySet() implementation in multiple calls final calls up getCeilingEntry() function

final Entry getCeilingEntry(K key) {
    Entry p = root;
    while (p != null) {
        int cmp = compare(key, p.key);
        if (cmp < 0) {
            if (p.left != null)
                p = p.left;
            else
                return p;
        } else if (cmp > 0) {
            if (p.right != null) {
                p = p.right;
            } else {
                Entry parent = p.parent;
                Entry ch = p;
                while (parent != null && ch == parent.right) {
                    ch = parent;
                    parent = parent.parent;
                }
                return parent;
            }
        } else
            return p;
    }
    return null;
}

SO i guess to get the actual map from the created submap; the time complexity is more than O(1).