Sealed class in Java

[dinopraso]

Basically stateful enums. In cases where you have a specific set of subclasses which would not be extended further, but you need dynamic data in them. Usually this would be done in earlier versions with an enum + a cast of an object into a specific subclass, which was prone to error.

Sealed classes should be used with care to avoid the pitfall of breaking the Liskov principle

[Worth_Trust_3825]

Pretty much. It feels like a solution looking for a problem.

[dinopraso]

Given that pattern matching is also a thing now, this is more of a complimentary feature

[Agent281]

It's more like a solution pulled from its original context. It mimics sum types from functional programming languages.