设计模式--行为模式--迭代模式--Java
Intent 目的

Providea way to access the elements of an aggregate object sequentially withoutexposing its underlying representation.提供一种方法顺序访问一个聚合对象中各个元素, 而又不需暴露该对象的内部表示。

applicability 适应性

to access an aggregate object's contents without exposing its internal representation.获取集合元素而不暴漏内部结构组织与逻辑。to support multiple traversals of aggregate objects.支持多种遍历方式。to provide a uniform interface for traversing different aggregate structures (that is, to support polymorphiciteration).为不同的集合提供一个统一的接口遍历集合。