In Kotlin, the static
keyword from Java is not used. Instead, Kotlin has its own mechanism for declaring and accessing static members, called companion objects. A companion object is a special object that is tied to the class in which it is declared, and its members can be accessed directly from the class without needing an instance of that class. Here's how you can use companion objects to achieve the equivalent of static members in Kotlin:
class MyClass {
companion object {
const val myStaticVariable = 42
fun myStaticMethod() {
println("This is a static method.")
}
}
}
In the above example, myStaticVariable
is a static variable declared inside the companion object, and myStaticMethod()
is a static method. You can access them using the class name:
val value = MyClass.myStaticVariable
MyClass.myStaticMethod()
Note that you don't need to create an instance of MyClass
to access the static members because they are associated with the class itself through the companion object.
Companion objects can also implement interfaces and have extension functions, making them quite flexible. Additionally, if you don't provide a name for the companion object, it will be called Companion
by default, and you can access its members using the Companion
keyword:
class MyClass {
companion object Factory {
// ...
}
}
val instance = MyClass.Factory.create()
In this case, Factory
is the name given to the companion object, and create()
is a function inside it.
Using companion objects, you can achieve similar functionality to static members in Java within your Kotlin code.
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