scala 如何在scala中将字符串数组转换为int数组
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How to convert string array to int array in scala
提问by Mohammad Gharehyazie
I am very new to Scala, and I am not sure how this is done. I have googled it with no luck. let us assume the code is:
我对 Scala 很陌生，我不确定这是如何完成的。我没有运气就用谷歌搜索了它。让我们假设代码是：
var arr = readLine().split(" ")
Now arr is a string array. Assuming I know that the line I input is a series of numbers e.g. 1 2 3 4, I want to convert arr to an Int (or int) array.
现在 arr 是一个字符串数组。假设我知道我输入的行是一系列数字，例如 1 2 3 4，我想将 arr 转换为 Int（或 int）数组。
I know that I can convert individual elements with .toInt, but I want to convert the whole array.
我知道我可以使用 .toInt 转换单个元素，但我想转换整个数组。
Thank you and apologies if the question is dumb.
如果问题很愚蠢，谢谢并道歉。
回答by Marth
Applying a function to every element of a collection is done using .map:
将函数应用于集合的每个元素是使用.map以下方法完成的：
scala> val arr = Array("1", "12", "123")
arr: Array[String] = Array(1, 12, 123)
scala> val intArr = arr.map(_.toInt)
intArr: Array[Int] = Array(1, 12, 123)
Note that the _.toIntnotation is equivalent to x => x.toInt:
请注意，该_.toInt符号等效于x => x.toInt：
scala> val intArr = arr.map(x => x.toInt)
intArr: Array[Int] = Array(1, 12, 123)
Obviously this will raise an exception if one of the element is not an integer :
显然，如果元素之一不是整数，这将引发异常：
scala> val arr = Array("1", "12", "123", "NaN")
arr: Array[String] = Array(1, 12, 123, NaN)
scala> val intArr = arr.map(_.toInt)
java.lang.NumberFormatException: For input string: "NaN"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Integer.parseInt(Integer.java:580)
at java.lang.Integer.parseInt(Integer.java:615)
at scala.collection.immutable.StringLike$class.toInt(StringLike.scala:272)
...
... 33 elided
回答by Xavier Guihot
Starting Scala 2.13, you might want to use String::toIntOptionin order to safely cast Strings to Option[Int]s and thus also handle items that can't be cast:
从 开始Scala 2.13，您可能想要使用String::toIntOption以安全地将Strings 强制转换为Option[Int]s，从而也处理无法强制转换的项目：
Array("1", "12", "abc", "123").flatMap(_.toIntOption)
// Array[Int] = Array(1, 12, 123)
