What Is The Difference Between Var And Val In Kotlin

How To Articles

Hey there! Today, I want to talk to you about a topic that has often confused me when I first started learning Kotlin: the difference between var and val. These two keywords are used to declare variables in Kotlin, but they behave quite differently. Let’s dive in and explore the nuances of var and val in Kotlin.

The var Keyword

When you declare a variable using the var keyword, you are telling the compiler that the value of that variable can be changed later in the code. In other words, it is a mutable variable. Let me give you an example:

var myName = "John"

Here, I’ve declared a variable called myName and assigned it the initial value of “John”. Later in the code, I can change the value of this variable if needed. For example:

myName = "Jane"

Now, the value of myName has been changed from “John” to “Jane”.

Using var is useful when you have a variable that needs to be updated or reassigned multiple times throughout your program. However, it’s important to note that using var can make your code more prone to bugs and unintended side effects if not used carefully.

The val Keyword

On the other hand, when you declare a variable using the val keyword, you are indicating that the value of that variable is immutable. Once you assign a value to a val, you cannot change it later in the code. Let’s see an example:

val pi = 3.14

Here, I’ve declared a constant called pi and assigned it the value of 3.14. Since it’s a val, its value cannot be changed later in the code. If you try to reassign a value to a val, you’ll get a compilation error.

Using val is beneficial when you have a value that should not change throughout your program. It provides immutability, which can make your code more readable, maintainable, and less prone to bugs.

Conclusion

Understanding the difference between var and val is crucial in Kotlin. By using var, you are declaring a mutable variable that can be changed later in the code. In contrast, by using val, you are declaring an immutable variable that cannot be reassigned once a value is assigned to it.

Personally, I find val to be my default choice unless I know I need to modify the variable later. I prefer immutability because it helps me write safer and more predictable code.

I hope this article has helped clarify the difference between var and val in Kotlin. Happy coding!