Sealed interface can be converted to sealed class

Reports sealed interfaces that have no properties and can be converted to sealed classes.

Sealed classes may be preferred over sealed interfaces when you want to ensure a single inheritance hierarchy or plan to add state (properties) in the future.

Example:

sealed interface Result<out T : Any>
class Success<T : Any>(val result: T) : Result<T>
class Error(val throwable: Throwable) : Result<Nothing>

sealed class Result<out T : Any>
class Success<T : Any>(val result: T) : Result<T>()
class Error(val throwable: Throwable) : Result<Nothing>()

Locating this inspection

By ID

Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.

ConvertSealedInterfaceToSealedClass

Via Settings dialog

Path to the inspection settings via IntelliJ Platform IDE Settings dialog, when you need to adjust inspection settings directly from your IDE.

Settings or Preferences | Editor | Inspections | Kotlin | Style issues

Inspection ID: ConvertSealedInterfaceToSealedClass

Suppressing Inspection

You can suppress this inspection by placing the following comment marker before the code fragment where you no longer want messages from this inspection to appear:

//noinspection ConvertSealedInterfaceToSealedClass

More detailed instructions as well as other ways and options that you have can be found in the product documentation:

IntelliJ IDEA 2026.2

Inspection Details
By default bundled with:	IntelliJ IDEA 2026.2, Qodana for JVM 2026.2,

Last modified: 30 June 2026