通过比较scala中的键获取值

val map = Map("key1" -> "value1", "key2" -> "value2", "key3" -> "value3")
val value = map("key2")
println(value) // 输出：value2

val map = Map("key1" -> "value1", "key2" -> "value2", "key3" -> "value3")
val value = map.get("key2").getOrElse("default")
println(value) // 输出：value2

val map = Map("key1" -> "value1", "key2" -> "value2", "key3" -> "value3")
val key = "key2"
val value = map match {
  case m if m.contains(key) => m(key)
  case _ => "default"
}
println(value) // 输出：value2