Android Development with Kotlin

Type parameters versus type arguments

Functions have parameters (variables declared inside a function declaration) and arguments (the actual value that is passed to a function). Similar terminology applies to generics. A type parameter is a blueprint or placeholder for a type declared in a generic, and a type argument is an actual type used to parametrize a generic.

We can use a type parameter in a method signature. This way, we can make sure that we will be able to add items of a certain type to our list and retrieve items of a certain type:

    class SimpleList<T> { 
 
       fun add(item:T) { // 1 
           // code 
       }  
       fun get(intex: Int): T { // 2 
           // code 
       } 
    } 

1. The generic type parameter T is used as the type for the item.
2. The type parameter is used as the return ...