I have two variables and I want to assign the same value to both of them at the same time, something like below:
var allGood: Boolean = false
val deviceId: String = "3550200583"
var isValidId: Boolean = false
allGood = isValidId = deviceId.length > 0 && deviceId.length <= 16
Is there any way to achieve this?
Because assignment is not an expression in Kotlin, you can't do multiple assignments that way. But there are other ways. The most obvious is simply:
isValidId = deviceId.length > 0 && deviceId.length <= 16
allGood = isValidId
A more idiomatic (if longer) way is:
(deviceId.length > 0 && deviceId.length <= 16).let {
allGood = it
isValidId = it
}
(By the way, you can simplify the condition to deviceId.length in 1..16.)
There are a couple of reasons why Kotlin doesn't allow this. The main one is that it's incompatible with the syntax for calling a function with named parameters: fn(paramName = value). But it also avoids any confusion between = and == (which could otherwise cause hard-to-spot bugs). See also here.
What about:
var allGood: Boolean = false
val deviceId: String = ...
val isValidId: Boolean = (deviceId.length in 1..16).also { allGood = it }
.also allows you to perform additional operations with the value that it receives and then returns the original value.
Another way is to do it like this:
val deviceId: String = "3550200583";
val condition = deviceId.length > 0 && deviceId.length <= 16
var (allGood, isValidId) = arrayOf(condition, condition);
