为什么`阵列（0,1,2）==阵列（0,1,2）`不会返回预期的结果？ [英] Why does `Array(0,1,2) == Array(0,1,2)` not return the expected result?

问题描述

据我了解，Scala的==定义了两个对象的自然平等的。

As far as I understand, Scala's == defines the natural equality of two objects.

我预计，阵列（0,1,2）==阵列（0,1,2）比较自然的平等。例如，检查是否当与其它阵列的对应元件相比，该数组中的所有元素返回true。

I expected that Array(0,1,2) == Array(0,1,2) compares the natural equality. For example, checks if all elements of the array return true when compared with the corresponding elements of the other array.

人告诉我，Scala的阵列只是一个Java [] 只比较认同。那岂不是更有意义的覆盖的等于方法比较自然的平等呢？

People told me that Scala's Array is just a Java [] which only compares identity. Wouldn't it be more meaningful to override Array'sequals method to compare natural equality instead?

推荐答案

斯卡拉2.7试图将功能添加到Java [] 阵列，跑到角落案件是有问题。斯卡拉2.8已经宣布，数组[T] 是 T [] ，但它提供的包装和等价物。

Scala 2.7 tried to add functionality to Java [] arrays, and ran into corner cases that were problematic. Scala 2.8 has declared that Array[T] is T[], but it provides wrappers and equivalents.

请尝试以下2.8（编辑/注：为RC3的， GenericArray 是 ArraySeq - 感谢返璞词指出这一点）：

Try the following in 2.8 (edit/note: as of RC3, GenericArray is ArraySeq--thanks to retronym for pointing this out):

import scala.collection.mutable.{GenericArray=>GArray, WrappedArray=>WArray}
scala> GArray(0,1,2) == GArray(0,1,2)
res0: Boolean = true

scala> (Array(0,1,2):WArray[Int]) == (Array(0,1,2):WArray[Int])
res1: Boolean = true

GenericArray 行为就像阵列，但在添加了所有的Scala集合东西。 WrappedArray 包装的Java [] 阵列;以上，我投一个普通数组，然后比较了包裹阵列（不是调用隐式转换功能更容易）。这些包装，虽然背靠一个 [] 阵列，也给你所有的收集东西。

GenericArray acts just like Array, except with all the Scala collections goodies added in. WrappedArray wraps Java [] array; above, I've cast a plain array to it (easier than calling the implicit conversion function) and then compared the wrapped arrays. These wrappers, though backed by a [] array, also give you all the collection goodies.

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