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

问题描述

给定一些 Kotlin 中的数组

Given some arrays in Kotlin

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

Kotlin std-lib 是否有内置函数来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?

从而导致:

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

equals() 实际上在两种情况下都返回 false，但也许 Kotlin 有可以使用的内置函数?

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

有静态函数 java.utils.Arrays.deepEquals(a.toTypedArray(), b.toTypedArray()) 但我更喜欢实例方法，因为它可以更好地与选项配合使用.

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 中你可以使用 contentEquals 和 contentDeepEquals 比较两个数组的结构相等性.例如:

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."

数组总是使用 equals() 进行比较，就像所有其他对象一样"(反馈请求:数据类限制 | Kotlin 博客).

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

所以 a.equals(b) 只会在 a 和 b 引用同一个数组时返回 true.

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

但是，您可以使用 extension 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)

附言Feedback Request: Limitations on Data Classes 上的评论|Kotlin 博客也值得一读，特别是评论 39364.

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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