在Java中,数组可以这样初始化:

int numbers[] = new int[] {10, 20, 30, 40, 50}

Kotlin的数组初始化是怎样的?


当前回答

你可以简单地使用现有的标准库方法,如下所示:

val numbers = intArrayOf(10, 20, 30, 40, 50)

使用一个特殊的构造函数可能是有意义的:

val numbers2 = IntArray(5) { (it + 1) * 10 }

你传递一个大小和一个lambda来描述如何初始化这些值。以下是文档:

/**
 * Creates a new array of the specified [size], where each element is calculated by calling the specified
 * [init] function. The [init] function returns an array element given its index.
 */
public inline constructor(size: Int, init: (Int) -> Int)

其他回答

I think one thing that is worth mentioning and isn't intuitive enough from the documentation is that, when you use a factory function to create an array and you specify it's size, the array is initialized with values that are equal to their index values. For example, in an array such as this: val array = Array(5, { i -> i }), the initial values assigned are [0,1,2,3,4] and not say, [0,0,0,0,0]. That is why from the documentation, val asc = Array(5, { i -> (i * i).toString() }) produces an answer of ["0", "1", "4", "9", "16"]

这里有一个例子:

fun main(args: Array<String>) {
    val arr = arrayOf(1, 2, 3);
    for (item in arr) {
        println(item);
    }
}

您还可以使用游乐场来测试语言特性。

我的回答补充了@maroun,这些是初始化数组的一些方法:

使用数组

val numbers = arrayOf(1,2,3,4,5)

使用严格的数组

val numbers = intArrayOf(1,2,3,4,5)

混合矩阵类型

val numbers = arrayOf(1,2,3.0,4f)

嵌套数组

val numbersInitials = intArrayOf(1,2,3,4,5)
val numbers = arrayOf(numbersInitials, arrayOf(6,7,8,9,10))

能够从动态代码开始

val numbers = Array(5){ it*2}

这里有一个简单的例子

val id_1: Int = 1
val ids: IntArray = intArrayOf(id_1)

在全局声明int array

var numbers= intArrayOf()

方法用value初始化数组

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    //create your int array here
    numbers= intArrayOf(10,20,30,40,50)
}