CODEWITHSUNDEEP
intellij-ideakotlinrefactoring
alilosoft
alilosoft

Reputation: 331

How to move a function from one Kotlin class to another using IntelliJ?

I'm using IntelliJ IDEA to refactor some Kotlin code. I have two classes in the same file and I want to move a function from one class to another using Refactor -> Move (F6), but that doesn't work, and I get tooltip message that says: "Cannot perform refactoring. Move declaration is only supported for top-level declarations and nested classes". Am I doing something wrong? Or that refactoring is simply not supported?

[edit1] I tried to do the same operation with Java classes and everything works perfectly; so why this is not allowed for Kotlin?

[edit2] I thought that the problem is only when to two classes are in the same file, but it turns out that is not possible to move a function between classes in separate files!

Upvotes: 14

Views: 3223

Answers (2)

Tor Brick
Tor Brick

Reputation: 81

There is an easy, but slightly janky, work around.

You just need to wrap the function you want to move in a class:

class TopLevelClass {
    fun functionToMove() {
        //...
    }
}

wrap it in a new class

class TopLevelClass {
    class TemporaryMoveClass{ /** you can now move this entire new class */
        fun functionToMove() {
            //...
        }
    }
}

and after you do the refactor, delete the temporary wrapper class you created.

The janky part is that you need to replace all instances of functionToMove() with NewTopLevelClass.functionToMove() yourself.

One of the major benefits of doing it this way, rather than just cut and pasting it yourself, is that as soon as you wrap it in the TemporaryMoveClass it will tell you any parameters you need to introduce(Refactor>Extract>Parameter). And then you can do that inside the original TopLevelClass before you move it. (this preserves the types of any TopLevelClass properties you were using, and automatically introduces the new parameter(s) into the existing function calls)

Upvotes: 0

Andy K
Andy K

Reputation: 7282

It's a well-known Kotlin-only problem.

  • in IDEA (both free and paid editions);
  • in Android Studio.

Official ticket

Upvotes: 5

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