How Iterator implement in TreeSet

Question

I read java source about TreeSet , but I can not find the implement of Iterator in TreeSet. Could anybody tell me how Iterator implements in TreeSet, and where is the source code in TreeSet? thanks!

Answer 1

Well, if you look at the source code of TreeSet<E>.iterator() you see:

public Iterator<E> iterator() {
    return m.navigableKeySet().iterator();
}

Next search for the definition of m:

private transient NavigableMap<E,Object> m;

So obviously TreeSet points to a NavigableMap which is not really a surprise because TreeSet's JavaDoc says:

A NavigableSet implementation based on a TreeMap.

Okay, so let us check the source code of TreeMap. There you will find the method navigableKeySet() which was referenced above, pointing to a member named navigableKeySet which is of type TreeMap.KeySet<K>, a static inner class. There in turn you will find an iterator() method and so forth. The TreeMap class contains quite a lot of inner classes, the whole structure is pretty complex, but if you are interested you can sort it out by yourself. I think I gave you a good headstart. ;-)