[Kotlin] Array List ArrayList

Array is mutable, but fixed length. Which means you can modify items in the Array, but you cannot add / remove item;

    // Array is fixed length, you cannot add or remove item
    val ary: Array<String> = arrayOf("Wan", "Zhen", "Tian")
    ary[1] = "gg"
    println(ary.contains("gg")) // true
    val mixedAry = arrayOf("Zhen", 23, true)
    val numAry: IntArray = intArrayOf(1,2,3) // doubleArrayOf ...
    val states = arrayOf("NIVDA", "APPLA")
    val allStates = states + ary // concat Array of string
    println(allStates.size) // 5

 

List is immutable, you cannot reassign value for list itenm ,you cannot add / remove item;

    val list: List<String> = listOf("Wan", "Zhen", "Tian")
    // list[0] = "gg" // ERROR:: List is immutable
    val list2: List<String> = listOf("Wan2", "Zhen2", "Tian2")
    val allList = list + list2
    println(allList.size) // 6
    println(allList.isEmpty()) // false
    println(allList.contains("Wan")) // true

 

ArrayList is mutable, you can add / remove itmes from ArrayList:

    // arrayList is mutatable
    val aryList = arrayListOf("Wan", "Zhen", "Tian")
    aryList.add("Josh")
    aryList.add(1, "Jack")
    println(aryList) // [Wan, Jack, Zhen, Tian, Josh]
    println(aryList.remove("Wan")) // true
    val subList = aryList.subList(1, 2)
    println(subList) // ["Jack"]