Kotlin：未解决的参考

Question

Kotlin：未解决的参考：totalFee

我只是在做这个小虚拟程序来练习，但它说totalFee 在尝试将值打印到屏幕时无法解析。我已经看了一段时间了，不知道为什么。 daysRented 是先前在程序中声明的 int。

if (daysRented <= 10){
    if(insPolicy == true){
       val totalFee = (shortTermRate * daysRented) + (insRate * daysRented)
    }
    else{
        val totalFee = shortTermRate * daysRented
    }
}
else{
    if(insPolicy == true){
        val totalFee = (longTermRate * daysRented) + (insRate * daysRented)
    }
    else{
        val totalFee = longTermRate * daysRented
    }
}
println("Rental fee: $totalFee")

Answer 1

if 是一个表达式，所以我会把它写成

val totalFee = if (daysRented <= 10){
    if(insPolicy == true){ // can just be if (insPolicy)
        (shortTermRate * daysRented) + (insRate * daysRented)
    }
    else{
        shortTermRate * daysRented
    }
}
else{
    if(insPolicy == true){
        (longTermRate * daysRented) + (insRate * daysRented)
    }
    else{
        longTermRate * daysRented
    }
}

确实应该改进到

val termRate = if (daysRented <= 10) shortTermRate else longTermRate 
val totalFee = 
    if (insPolicy) {
        (termRate * daysRented) + (insRate * daysRented)
    } 
    else {
        termRate * daysRented
    }

甚至

val totalFee = termRate * daysRented + 
    (if (insPolicy) insRate * daysRented else 0)

Answer 2

使用此代码。

val totalFee: Int
if (daysRented <= 10){
    if(insPolicy){
       totalFee = (shortTermRate * daysRented) + (insRate * daysRented)
    }
    else{
        totalFee = shortTermRate * daysRented
    }
}
else{
    if(insPolicy){
        totalFee = (longTermRate * daysRented) + (insRate * daysRented)
    }
    else{
        totalFee = longTermRate * daysRented
    }
}
println("Rental fee: $totalFee")