Kotlin 三元条件运算符到典型的 if-else

Question

有人可以将其转换为 Kotlin 中的 if-else 语句，以便我可以理解代码吗？

return email != null
        ? email.isEmpty
        ? "Please enter your email!"
        : RegExp("^[a-zA-Z0-9+_.-]+@[a-zA-Z0-9.-]+.[a-z]")
        .hasMatch(email)
        ? ""
        : "Please enter a valid email!"
        : "Please enter your email!";

Answer 1

return if (email != null) {
         if (email.isEmpty) "Please enter your email!"
         else if (RegExp("^[a-zA-Z0-9+_.-]+@[a-zA-Z0-9.-]+.[a-z]").hasMatch(email)) ""
         else "Please enter a valid email!"
       } else "Please enter your email!"

Answer 2

return if (email != null){
            when {
                email.isEmpty() -> "Please enter your email!"
                RegExp("^[a-zA-Z0-9+_.-]+@[a-zA-Z0-9.-]+.[a-z]"). hasMatch(email) -> ""
                else -> "Please enter a valid email!"
            }
        } else "Please enter a valid email!"

Answer 3

@ArtyomSkrobov 的回答是对该代码的字面解释。

我只是想补充一下，因为原来的逻辑很混乱：可以在 when 语句中重新排列并使用 Kotlin 标准库 functions/classes 更容易理解：

return when {
    email.isNullOrEmpty() -> "Please enter your email!"
    !email.matches(Regex("^[a-zA-Z0-9+_.-]+@[a-zA-Z0-9.-]+.[a-z]")) -> "Please enter a valid email!"
    else -> ""
}

Kotlin 三元条件运算符到典型的 if-else

Kotlin Ternary conditional operator to typical if-else

kotlin

if-statement

ternary