If you want to make a class use generics, add <T> after the class name and before the constructor (if there is one). You can then use T as a placeholder for the generic type, such as in constructor parameters.

Here, we have a Transport that can only transport objects of type T. Since critterCarrier is passed a Frog, it will be a Transport<Frog> and can only transport frogs.

• the documentation
• Elements of Kotlin