什么是迭代器模式
一句话总结 : 数据集合按照顺序遍历.....
类图显示
现成的书图
直接上代码
public interface Iterator<out T> {
public operator fun hasNext(): Boolean
public fun next(): T
}
public interface Aggregate<out T> {
fun iterator(): Iterator<T>
}
class BookshelfIterator(val shelf: Bookshelf) : Iterator<Book> {
private var index: Int = 0
override fun hasNext(): Boolean {
return if (index < shelf.length() - 1) {
index++
true
} else {
false
}
}
override fun next(): Book {
return shelf.get(index)
}
}
public class Bookshelf : Aggregate<Book> {
private val books = mutableListOf<Book>()
fun append(book: Book) {
books.add(book)
}
fun remove(index: Int) {
books.removeAt(index)
}
fun get(index: Int): Book = books[index]
fun length(): Int = books.size
override fun iterator(): Iterator<Book> {
return BookshelfIterator(this)
}
}
data class Book(var title: String = "标题", val price: Int = 10)
测试运行
fun main(args: Array<String>) {
Bookshelf().run {
for (i in 0..10) {
this.append(Book("title$i", i))
}
println(this)
this.iterator().run {
while (this.hasNext()) {
this.next().run {
println("${this.title}======${this.price}")
}
}
}
}
}
运行结果
iterator.Bookshelf@266474c2
title1======1
title2======2
title3======3
title4======4
title5======5
title6======6
title7======7
title8======8
title9======9
title10======10
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