There is no static
keyword in Kotlin.
What is the best way to represent a static
Java method in Kotlin?
30 s
You place the function in the “companion object”.
So the java code like this:
class Foo {
public static int a() { return 1; }
}
will become
class Foo {
companion object {
fun a() : Int = 1
}
}
You can then use it from inside Kotlin code as
Foo.a();
But from within Java code, you would need to call it as
Foo.Companion.a();
(Which also works from within Kotlin.)
If you don’t like having to specify the Companion
bit you can either add a @JvmStatic
annotation or name your companion class.
From the docs:
Companion Objects
An object declaration inside a class can be marked with the
companion
keyword:class MyClass { companion object Factory { fun create(): MyClass = MyClass() } }
Members of the companion object can be called by using simply the class
name as the qualifier:val instance = MyClass.create()
…
However, on the JVM you can have members of companion objects generated
as real static methods and fields, if you use the@JvmStatic
annotation. See the Java interoperability section for more details.
Adding the @JvmStatic
annotation looks like this
class Foo {
companion object {
@JvmStatic
fun a() : Int = 1;
}
}
and then it will exist as a real Java static function, accessible from
both Java and Kotlin as Foo.a()
.
If it is just disliked for the Companion
name, then you can also
provide an explicit name for the companion object looks like this:
class Foo {
companion object Blah {
fun a() : Int = 1;
}
}
which will let you call it from Kotlin in the same way, but
from java like Foo.Blah.a()
(which will also work in Kotlin).