如何在kotlin中创建重复对象的数组？

Question

我知道如何通过创建循环来实现它,但我想知道是否有更简单的方法？

例如,我想创建一个数组,Point它们将全部具有(0,0)或增加x,y其索引.

Answer 1

Array 有一个特殊的构造函数用于这样的事情:

/**
 * Creates a new array with 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) -> T)

它可以用于两个用例:

val points = Array(5) {
    Point(0, 0)
}
//[Point(x=0, y=0), Point(x=0, y=0), Point(x=0, y=0), Point(x=0, y=0), Point(x=0, y=0)]


val points2 = Array(5) { index->
    Point(index, index)
}
//[Point(x=0, y=0), Point(x=1, y=1), Point(x=2, y=2), Point(x=3, y=3), Point(x=4, y=4)]

Answer 2

在重复功能是另一种方法：

data class Point(val x: Int, val y: Int)

@Test fun makePoints() {
    val size = 100

    val points = arrayOfNulls<Point>(size)

    repeat(size) { index -> points[index] = Point(index,index) }
}