Side Topic: Iterator in Java

Interface Iterator

Java 中常见的数据结构和它内置的iterator: create an instance o f iterator

Iterator 的subInterface

API 1: E next()

Returns the next element in the iteration

用法：iterator.next()

Example: ArrayList

Example: set

Example treeSet

API2: boolean hasNext()

Return true if the iteration has more elements

Example: ArrayList

Example: set

Example treeSet

思考：

• 判断还有没有下一个

• 真的拿出下一个

• 内部的use case：我需要给下一次遍历做好准备

API 3: void forEachRemaining (Consumer<? super E> action)

Performs the given action for each remaining element until all elements has been processed or the action throws an exception

API 4 void remove()

Removes from the underlying colleciton the last element returneed by this iterator(optional operation)