Kotlin 基础教程之数组容器

kotlin 基础教程之数组容器

arrays

kotlin 标准库提供了arrayof()创建数组， **arrayof创建特定类型数组

val array = arrayof(1, 2, 3)
val countries = arrayof("uk", "germany", "italy")
val numbers = intarrayof(10, 20, 30)
val array1 = array(10, { k -> k * k })
val longarray = emptyarray<long>()
val studentarray = array<student>(2)
studentarray[0] = student("james")

和java不一样，kotlin 的数组是容器类， 提供了 bytearray, chararray, shortarray, intarray, longarray, booleanarray, floatarray, and doublearray。

lists

list是有序容器，kotlin 标准库通过listof()创建list

val intlist: list<int> = listof(20, 5, 10)
val emptylist: list<string> = emptylist<string>()
val nonnulls: list<string> = listofnotnull<string>(null, "a", "b", "c")

val doublelist: arraylist<double> = arraylistof(84.88, 100.25, 999.99)

其中，intlist, emptylist, nonnulls是只读的实例，要修改这些list，需要进行类型转换

(intlist as abstractlist<int>).set(0, 30)
(nonnulls as java.util.arraylist).addall(arrayof("x", "y"))

maps

map是<key, value>容器， kotlin提供mapof创建map

val map = mapof("a" to 1, "b" to 2, "c" to 3)
val value = map.get(b)

val states: mutablemap<string, string>= mutablemapof("al" to "alabama", 
    "ak" to "alaska", "az" to "arizona")

val customers: java.util.hashmap<int, customer> = hashmapof(1 to
    customer("dina", "kreps", 1), 2 to customer("andy", "smith", 2))

val linkedhashmap: java.util.linkedhashmap<string, string> =
    linkedmapof("red" to "#ff0000","azure" to "#f0ffff","white" to "#ffffff")

val sortedmap: java.util.sortedmap<int, string> = sortedmapof(4 to "d",
    1 to "a", 3 to "c", 2 to "b")

sets

set是没有重复项的容器， kotlin提供setof创建set

val intset: set<int> = setof(1, 21, 21, 2, 6, 3, 2) //1,21,2,6,3
val hashset: java.util.hashset<book> = hashsetof(
    book("jules verne", "around the world in 80 days paperback", 2014, "978-1503215153"),
    book("jules verne", "around the world in 80 days paperback", 2014, "978-1503215153"))
val sortedintegers: java.util.treeset<int> = sortedsetof(11, 0, 9, 11, 9, 8)

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