Issue
What is the difference between var
and val
in Kotlin?
I have gone through this link:
KotlinLang: Properties and Fields
As stated on this link:
The full syntax of a read-only property declaration differs from a mutable one in two ways: it starts with val instead of var and does not allow a setter.
But just before there is an example which uses a setter.
fun copyAddress(address: Address): Address {
val result = Address() // there's no 'new' keyword in Kotlin
result.name = address.name // accessors are called
result.street = address.street
// ...
return result
}
What is the exact difference between var
and val
?
Why do we need both?
This is not a duplicate of Variables in Kotlin, differences with Java: 'var' vs. 'val'? as I am asking about the doubt related to the particular example in the documentation and not just in general.
Solution
In your code result
is not changing, its var
properties are changing. Refer comments below:
fun copyAddress(address: Address): Address {
val result = Address() // result is read only
result.name = address.name // but not their properties.
result.street = address.street
// ...
return result
}
val
is same as the final
modifier in java. As you should probably know that we can not assign to a final
variable again but can change its properties.
Answered By - Sachin Chandil
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