Variables in Scala in Scala

Variable declaration:

To create / declare a variable, we must tell Scala the variable's data type followed by the variable's name, like so:

val name: String = "AlgoCademy"

creates a String variable named name.

Variable initialization:

We can initialize a variable to an initial value in the same line as it is created using the assignment operator (=). This code:

val name = "AlgoCademy"

creates a new String variable named name and assigns it an initial value of "AlgoCademy".

When executing this code, Scala will allocate some memory, then it will store the string "AlgoCademy" in that memory and finally will attach this name label to that memory location.

You can think of this memory location as a box. In that box, we put string "AlgoCademy". Then, we put the label name on this box.

Accessing values in variables:

Now we can use this label anywhere in our program to access the value in that box. We can print it for example:

// We create and initialize two variables:
val name = "AlgoCademy"
val age = 10

// We access the variables:
println(name)
println(age)

The output of this code is:

AlgoCademy
10

Important notice:

We almost never want to create a variable without initializing it! It's a bad coding practice and can create a lot of problems.

val vs var:

Scala has two ways to declare a variable. val declares an immutable value — once set, it can't be reassigned. var declares a mutable variable you can reassign later. Prefer val; Scala favors immutability.

val pi = 3.14   // immutable — reassigning pi is an error
var score = 0   // mutable
score = 10      // OK: var can change

You'll see both throughout the coding tutorials — reach for val unless a value genuinely needs to change.

Assignment
Follow the Coding Tutorial and let's create some variables.

Hint
Look at the examples above if you get stuck.