Groovy 设计模式 -- 迭代器模式

Iterator Pattern

http://groovy-lang.org/design-patterns.html#_flyweight_pattern

迭代器模式，允许顺序访问 聚集对象中的中元素， 而不用关心起内部是如何实现的。

groovy有自己的语言内置的闭包操作， 例如 each

The Iterator Pattern allows sequential access to the elements of an aggregate object without exposing its underlying representation.

Groovy has the iterator pattern built right in to many of its closure operators, e.g. each and eachWithIndex as well as the for .. in loop.

例子

def printAll(container) {
    for (item in container) { println item }
}

def numbers = [ 1,2,3,4 ]
def months = [ Mar:31, Apr:30, May:31 ]
def colors = [ java.awt.Color.BLACK, java.awt.Color.WHITE ]
printAll numbers
printAll months
printAll colors

colors.eachWithIndex { item, pos ->
    println "Position $pos contains '$item'"
}