Is converting a sealed class to an interface a bin...

# library-development

[Drew Hamilton]

Is converting a sealed class to an interface a binary compatible change? I’m leaning toward “effectively yes other than some reflection problems” but not confident at all.

[altavir]

No it is not. It should not break compatibility for descendants, but it surely will for the class itself.

[Drew Hamilton]

In what sense? Can you give an example of a call that would work for the sealed class and not work for the interface (when the consumer is not recompiled)?

[altavir]

Their byte-code representation is different. There is surely difference on the reflection level. The general usage should be the same

[Zach Klippenstein (he/him) [MOD]]

I think if you're sealed class has any concrete methods, the bytecode to call them would be incompatible, especially if you don't use @JvmDefaults on your interface (but maybe even then).

[Drew Hamilton]

Good point on the concrete functions, the case I was thinking of happens to have none.

[elizarov]

It is invokevirtual vs invokeinterface at the bytecode level

[Drew Hamilton]

Ahhh never knew those were different! Thanks!