A major reason to choose to use a sealed class instead of interface would be if there is common property/function that you don’t want to be public. All members of an interface are always public. The restriction that members must be public can be worked around on an interface using extension functions/properties, but only if … Read more
Because in real-world APIs, sometimes we want to support specific extension points while restricting others. The Shape examples are not particularly evocative, though, which is why it might seem an odd thing to allow. Sealed classes are about having finer control over who can extend a given extensible type. There are several reasons you might … Read more
You can follow this link for examples. In short sealed classes gives you the control of which models, classes etc. that can implement or extend that class/interface. Example from the link: public sealed interface Service permits Car, Truck { int getMaxServiceIntervalInMonths(); default int getMaxDistanceBetweenServicesInKilometers() { return 100000; } } This interface only permits Car and … Read more
Options 3 and 4 would result in the class holding messageId twice. Once in the new class and once in its superclass. The solution is to declare but not define the variable in the superclass: sealed class Message { abstract val messageId: String } data class Track(val event: String, override val messageId: String): Message() This … Read more
Let’s discuss the difference between enums and sealed classes over various aspects with contrasting examples. This will help you choose one over the other depending on your use case. Properties Enum In enum classes, each enum value cannot have its own unique property. You are forced to have the same property for each enum value: … Read more