Is it possible to make void delegate extend Runnable for Java

As below code shown, currently I have to use a wrapper to pass my Action delegate to an Java API:

public delegate void Action();

public class ARunnable : Runnable {
    private readonly Action mAction;
    public ARunnable(Action action) {
        mAction = action;
    public void run() => mAction();

public class TestClass {
    private Handler mHandler = new Handler();
    public void test(Action action) { ARunnable(action));

And I’ve known that Elements will compile “Action” to an Java interface:

public interface Action {
void Invoke();

Since java.lang.Runnable is a very basic and standard Java interface, I think it’s better to make the generated Action interface to extend it, like what Elements have done to a void lambda expression.

Or be more advanced, Elements can auto replace all void delegate types with java.lang.Runnable directly only for Java, then there’s no cross-platform overhead to communicate with standard Java API.

Something to consider yes. However you can always (for now) use: () => action());

Nope…Lambda exp currently is very expensive for Java on Elements.

If you write ()=>action() ); in different classes, you will find there’re multiple anonymous class definitions are generated which are exactly the same except for their names.

That’s why I use a self-defined ARunnable instead.

True. because lambdas are always distinct (can’t really compare vastly different code)

And you know Android has 64k methods limit…So it’s worth to do more optmizations to reduce unnecessary class definitions.

Agreed. For what it’s worth you can easily change it locally:

we’re going to discuss this and consider it.