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?
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
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}
其他回答
这里有一个简单的例子
val id_1: Int = 1
val ids: IntArray = intArrayOf(id_1)
我想知道为什么没有人给出最简单的答案:
val array: Array<Int> = [1, 2, 3]
根据对我最初答案的一个评论,我意识到这只在注释参数中使用时才有效(这对我来说真的是出乎意料)。
看起来Kotlin不允许在注释之外创建数组文字。
例如,使用args4j库中的@Option查看以下代码:
@Option( name = "-h", aliases = ["--help", "-?"], usage = "Show this help" ) var help: Boolean = false
选项参数“aliases”的类型是Array<String>
当初始化下面的字符串检查
val strings = arrayOf("January", "February", "March")
我们可以使用原始int数组专用的arrayOf方法简单地初始化它:
val integers = intArrayOf(1, 2, 3, 4)
在我的情况下,我需要初始化我的抽屉项目。我通过以下代码填充数据。
val iconsArr : IntArray = resources.getIntArray(R.array.navigation_drawer_items_icon)
val names : Array<String> = resources.getStringArray(R.array.navigation_drawer_items_name)
// Use lambda function to add data in my custom model class i.e. DrawerItem
val drawerItems = Array<DrawerItem>(iconsArr.size, init =
{ index -> DrawerItem(iconsArr[index], names[index])})
Log.d(LOGGER_TAG, "Number of items in drawer is: "+ drawerItems.size)
自定义模型类-
class DrawerItem(var icon: Int, var name: String) {
}
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"]