scala，从 Some(value) 获取值 [英] scala, get values from Some(value)

问题描述

我目前正在尝试将自己读入 Scala.但我陷入了以下困境:

i am currently trying to read myself into scala. But i got stuck on the following:

val value: String = properties(j).attribute("value").toString
print(value)

xml 属性被读取并转换为字符串，但被视为Some(value)".我已经尝试了几件事，但似乎没有一个工作，当我自己用选项:字符串"(这是常见的解决方案)创建值时.有人知道摆脱Some("的简单方法吗?

The xml property is read and converted to a string, but gets viewed as "Some(value)". I have tried several things but none seems to work when not i myself created the value with "Option: String"(which was the common solution). Does somebody know an easy way to get rid of the "Some("?

您好马

推荐答案

您调用 toString 方法的值是 Option[String] 类型，而不是普通的 字符串.当有值时，你会得到Some(value)，而如果没有值，你会得到None.

The value you're calling the toString method on is an Option[String] type, as opposed to a plain String. When there is a value, you'll get Some(value), while if there's not a value, you'll get None.

因此，您需要处理可能返回的两种情况.通常这是通过匹配完成的:

Because of that, you need to handle the two possible cases you may get back. Usually that's done with a match:

val value: String = properties(j).attribute("value") match {
  case None => ""//Or handle the lack of a value another way: throw an error, etc.
  case Some(s: String) => s //return the string to set your value
}

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