如何在Kotlin中比较两个数组? [英] How to compare two arrays in Kotlin?

问题描述

给出Kotlin中的一些数组

Given some arrays in Kotlin

let a = arrayOf("first", "second")
val b = arrayOf("first", "second")
val c = arrayOf("1st", "2nd")

Kotlin std-lib是否有内置函数可以测试两个数组的每个元素的(值)相等性?

Are there built-in functions to the Kotlin std-lib that tests two arrays for (value) equality for each element?

因此导致:

a.equals(b) // true
a.equals(c) // false

equals()实际上在两种情况下都返回false，但是也许Kotlin内置了一个可以使用的函数?

equals() is actually returning false in both cases, but maybe there are built-in functions to Kotlin that one could use?

有一个静态函数java.utils.Arrays.deepEquals(a.toTypedArray(), b.toTypedArray())，但是我宁愿选择一个实例方法，因为它可以与可选方法一起使用.

There is the static function java.utils.Arrays.deepEquals(a.toTypedArray(), b.toTypedArray()) but I would rather prefer an instance method as it would work better with optionals.

推荐答案

在Kotlin 1.1中，您可以使用

In Kotlin 1.1 you can use contentEquals and contentDeepEquals to compare two arrays for structural equality. e.g.:

a contentEquals b // true
b contentEquals c // false

在Kotlin 1.0中，没有"Kotlin std-lib的内置函数来测试两个数组的每个元素的(值)相等性."

In Kotlin 1.0 there are no "built-in functions to the Kotlin std-lib that tests two arrays for (value) equality for each element."

与其他所有对象一样，总是使用equals()比较数组"(

"Arrays are always compared using equals(), as all other objects" (Feedback Request: Limitations on Data Classes | Kotlin Blog).

因此a.equals(b)仅在a和b引用同一数组时才会返回true.

So a.equals(b) will only return true if a and b reference the same array.

但是，您可以使用扩展名，创建自己的可选"友好方法功能.例如:

You can, however, create your own "optionals"-friendly methods using extension functions. e.g.:

fun Array<*>.equalsArray(other: Array<*>) = Arrays.equals(this, other)
fun Array<*>.deepEqualsArray(other: Array<*>) = Arrays.deepEquals(this, other)

P.S.对反馈请求:数据类的限制的评论| Kotlin博客也值得一读，特别是

P.S. The comments on Feedback Request: Limitations on Data Classes | Kotlin Blog are worth a read as well, specifically comment 39364.

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