How to create static fields, methods, and classes in…

In Kotlin, there is no direct concept of "static" as in Java. To achieve similar functionality, the following mechanisms are used:

Companion objects: Used to create static fields (properties) and methods associated with the class, not its instances.

class MyClass {
    companion object {
        const val TAG = "MyClass" // Static field
        fun create(): MyClass { // Static method
            return MyClass()
        }
    }
}

Package-level functions and properties: Functions and properties declared directly in a .kt file, outside any class. They can be accessed directly by name.

// MyFile.kt
const val GLOBAL_CONSTANT = 123 // Static field at package level

fun globalFunction() { // Static method at package level
    // ...
}

Object declarations: Declare a singleton. All its members (properties and functions) are essentially static.

object MySingleton {
    const val NAME = "Singleton" // Static field
    fun doSomething() { // Static method
        // ...
    }
}

For "static" nested classes: In Kotlin, nested classes do not have an implicit reference to the outer class by default. This is similar to static class in Java.

class OuterClass {
    class NestedClass { // Nested class, essentially static
        fun printMessage() {
            println("Hello from nested class")
        }
    }
}

How to create static fields, methods, and classes in Kotlin?