Kotlin Generics
Introduction
A List can hold numbers, words or really anything. That's why we call the List generic.
Generics are basically used to define which types a class can hold and which type an object currently holds.
Syntax
- class ClassName<TypeName>
- class ClassName<*>
- ClassName<in UpperBound>
- ClassName<out LowerBound>
- class Name<TypeName:UpperBound>
Parameters
| Parameter | Details |
|---|---|
| TypeName | Type Name of generic parameter |
| UpperBound | Covariant Type |
| LowerBound | Contravariant Type |
| ClassName | Name of the class |
Remarks
Implied Upper Bound is Nullable
In Kotlin Generics, the upper bound of type parameter T would be Any?. Therefore for this class:
class Consumer<T>
The type parameter T is really T: Any?. To make a non-nullable upper bound, explicitly specific T: Any. For example:
class Consumer<T: Any>
