Kotlin集合List Set Map使用介绍详解

    val arrayList = ArrayList<String>()
    val linkedList = LinkedList<String>()
    val hashSet = HashSet<String>()
    val hashMap = HashMap<String,Int>()

 val list = listOf<Int>(1, 2, 3)
 val set = setOf<Int>(1, 2, 3)
 val map = mapOf(1 to "Jack", 2 to "Rose")

 val mutableList = mutableListOf<Int>(1, 2, 3)
 val mutableSet = mutableSetOf<Int>(1, 2, 3)
 val mutableMap = mutableMapOf(1 to "Jack", 2 to "Rose")

    val list = listOf<Int>(1, 2, 3)
    //通常get的方式
    println(list.get(1))
    //之所以能使用[]类似数组的方式获取，是因为做了[]运算符重载，后面会讲到。
    println(list[1])
    //角标越界不会抛出异常，而是返回一个null
    println(list.getOrNull(3))
    //通过？：空合并操作符，？：左边的值为空，则返回右边的值
    println(list.getOrNull(3) ?: -1)
    //如果角标越界，不会抛出异常。而是返回{}lambda表达式中的值
    println(list.getOrElse(3) { -1 })

list.get(1)

list[1]

list.getOrNull(3)

list.getOrNull(3) ?: -1

  list.getOrElse(3) { -1 }

 val mutableList = mutableListOf<Int>(1, 2, 3)

   mutableList.set(1,2)
   mutableList[1] = 2

 mutableList.add(4)
 mutableList += 5

    mutableList -= 5
    mutableList.remove(5)

 mutableList.removeIf { it == 4 }

mutableList.removeIf { it.contains("H")}

    for (item in list) {
        println(item)
    }
    list.forEach {
        println(it)
    }
    list.forEachIndexed { index, value ->
        println("$index , $value")
    }

 val (first:Int,second:Int,third:Int) = listOf<Int>(1, 2, 3)

 val (first: Int, _, third: Int) = listOf<Int>(1, 2, 3)
 println("$first  $third")

    val set = setOf<Int>(1, 2, 3)
    set.elementAt(1)
    set.elementAtOrElse(1) { -1 }
    set.elementAtOrNull(1)

    val mutableSet = mutableSetOf<Int>(1, 2, 3)
    mutableSet += 4
    mutableSet -= 2
    mutableSet.remove(3)
    mutableSet.removeIf { it==4 }

   val list =  mutableSet.toList();
   val set =  mutableList.toSet();

    //ByteArray
    val byteArray = byteArrayOf(1,2,3)
    //IntArray
    val array = intArrayOf(1, 2, 3)
    //CharArray
    val charArray = charArrayOf('a','b','c')

val map = mapOf(Pair(1, "HanMei"), Pair(2, "LiLei"))

val map = mapOf(1 to "HanMei", 2 to "LiLei")

val mutableMap = mutableMapOf(1 to "HanMei", 2 to "LiLei")

    println(map[1])
    println(map.getValue(1))
    println(map.getOrDefault(1, "Default"))
    println(map.getOrElse(1) { "default" })

  map.forEach {
        println("%$it.key , ${it.value}")
    }
  map.forEach { (key, value) -> println("$key ,$value") }

   val mutableMap = mutableMapOf(1 to "HanMei", 2 to "LiLei")
    mutableMap += 3 to "XiaoHua"
    mutableMap.put(4, "XiaoHua")
    mutableMap.getOrPut(5) { "XiaoHua" }
    val getValue:()->String = {
        "value"
    }
    mutableMap.getOrPut(5) {getValue()}