Detailed explanation of container instances of objects

1. Iterator (iterator) and Enumeration (enumeration class) are both used to traverse collections, and they are both interfaces. The difference is that Enumeration can only read the data of the collection, while Iterator can delete data, and Iterator can replace Enumeration.

2. The types of sets include Vector, BitSet (a Vector composed of "binary bits"), Stack ("last in first out" (LIFO) collection), Hashtable ("key-value" pair).

3.Collection is the parent interface of Set and List. A List (list) must contain elements in a specific order, while a Set (set) cannot contain any repeated elements. Map, a series of "key-value" pairs. There are no duplicate key objects in the collection, and the value objects can be repeated.

4.Collection’s iterator() method can return an Iterator object for traversal.

5. If operations such as stacks and queues are involved, you should consider using List. If you need to quickly insert and delete elements, you should use LinkedList. If you need fast random access to elements, you should use ArrayLit.

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