Kotlin笔记6-Lambda编程1-集合的创建与遍历-List,Set,Map
4.1 Lambda编程1
- 集合
Java接口
List | Set | Map |
ArrayList,LinkedList | HashSet | HashMap |
- List
List
集合逐个添加
val list = ArrayList<String>()
list.add("Apple")
list.add("Banana")
...
listOf: 不可变集合
val list = listOf("Apple", "Banana", "Orange", "Pear", "Grape")
mutableListOf: 可变集合
val list1= mutableListOf("Apple", "Banana", "Orange", "Pear", "Grape")
list1.add("watermelon")
- Set
Set
Set初始化
SetOf: 不可变集合
val set= setOf("Apple","Banana","Orange","Pear","Grape")
mutableSetOf: 可变集合
- Map
Map: 键值对形式数据结构
Map添加数据(不推荐)
val map=HashMap<String,Int>()
map.put("Apple",1)
map.put("Banana",2)
map.put("Orange",3)
map.put("Pear",4)
map.put("Grape",5)//不推荐
Map添加数据(推荐)
val map1=HashMap<String,Int>()
map1["Apple"] = 1
map1["Banana"] = 2
map1["Orange"] = 3
map1["Pear"] = 4
map1["Grape"] = 5//推荐
读取数据
val number=map1["Apple"]
Map添加数据(简化)
to: infix函数
val map2= mapOf("Apple" to 1,"Banana" to 2,"Orange" to 3,"Pear" to 4,"Grape" to 5)
Example:
fun main() {
//再简化
val map= mapOf("Apple" to 1,"Banana" to 2,"Orange" to 3,"Pear" to 4,"Grape" to 5)
for((fruit,number) in map){
println("fruit is $fruit ,number is $number.")
}
}