How to create static variables and functions in Kotlin

In Kotlin, you have the const keyword that’s equal to the static keyword in Java.

The const keyword is used to create a variable that’s known to Kotlin before the compilation, so you don’t need to create an instance of a class to use it.

The val keyword is used to create an immutable variable, just like the final keyword in java.

Combined together, the const val keyword allows you to create static variables in Kotlin object as follows:

object MyObject {
    const val OBJ_DESCRIPTION = "An object with a static variable"
}

print(MyObject.OBJ_DESCRIPTION)
// An object with a static variable

The const val OBJ_DESCRIPTION above would be equal to final static String OBJ_DESCRIPTION in Java.

A static method can also be created in a Kotlin object just like creating a regular method:

object MyObject {
    const val description = "An object with a static variable"
    fun staticFun() = print("A static function")
}

print(MyObject.description)
MyObject.staticFun()

When you need to add static members to a class, however, you need to create a companion object inside the class and put the static members inside the object.

Here’s an example of a Kotlin class with static members:

class MyClass {
    companion object {
        const val staticVar = "A static variable"
        fun staticFun() = print("This is a static function")
    }
}

print(MyClass.staticVar)
// A static variable
MyClass.staticFun()

And that’s how you can create static variables and functions inside a Kotlin object or class types 😉