java - 谁能解释一下输出？？？我刚开始学习kotlin，所以请尽可能详细，谢谢

Question

• add() 的优先级是否比 set() 低？
• mutablelist 和 arraylist 可以使用容量/大小来区分吗？？？

fun main(args: Array<String>) {

    //get() and set()
    var arrOne:MutableList<Int> = mutableListOf<Int>(3, 7, 8)   //how does '3', '7' and '8' work?
    arrOne.add(11)
    arrOne.add(43)
    arrOne.add(35)
    arrOne.add(47)
    arrOne.set(0, 23)
    arrOne.set(1, 34)
    arrOne.set(2, 56)
    arrOne.set(3, 66)
    arrOne.set(4, 76)
    print(arrOne)
    println("\n" + arrOne.get(2))

    val arrTwo:ArrayList<String> = ArrayList<String>(3) //how does '3' work?
    println(arrTwo.size)
    arrTwo.add("x")
    arrTwo.add("t")
    arrTwo.add("c")
    arrTwo.add("g")
    arrTwo.set(1, "y")
    arrTwo.set(2, "z")
    println(arrTwo.size)
    print(arrTwo)
    println("\n" + arrTwo.get(0))
}

标签： javaandroidkotlin

Answer 1

@LppEdd - 谢谢我想通了

var arrOne:MutableList<Int> = mutableListOf<Int>(3) //will result in [3]
//add() extends the list
arrOne.add(11)  //[3, 11]
arrOne.add(43)  //[3, 11, 43]
arrOne.add(35)  //[3, 11, 43, 35]
arrOne.add(47)  //[3, 11, 43, 35, 47]
//set() replace the value at the given index
arrOne.set(0, 23)   //[23, 11, 43, 35, 47]
arrOne.set(1, 34)   //[23, 34, 43, 35, 47]
arrOne.set(2, 56)   //[23, 34, 56, 35, 47]
arrOne.set(3, 66)   //[23, 34, 56, 66, 47]