如何在Scala中为列表所有元素前置指定字符串？

Hey there! I've got you covered on this Scala task. Let's walk through how to add the prefix "test" to each element in your list and output them as a space-separated string.

最直接的实现方式 #

The core idea is to first transform each element in the list with the prefix, then join them together with spaces. Here's the straightforward code:

val lst = List("a","b","c")
// 先给每个元素添加前缀，再用空格拼接
val prefixedAndJoined = lst.map(element => "test" + element).mkString(" ")
println(prefixedAndJoined) // 输出: testa testb testc

更简洁的写法 #

Scala lets us write this more concisely if you prefer:

• Using string interpolation:

  val prefixedAndJoined = lst.map(element => s"test$element").mkString(" ")
  

• Using the underscore shortcut for single-parameter functions:

  val prefixedAndJoined = lst.map("test" + _).mkString(" ")
  

All these approaches do exactly the same thing: they iterate over each element, prepend "test" to it, then combine the resulting list into a single string with spaces between elements.

If you want to print the result directly without storing it in a variable, you can even do it in one line:

println(lst.map("test" + _).mkString(" "))

内容的提问来源于stack exchange，提问作者lak