Like classes, interfaces can be generic. Below is an example of a generic interface with a single type parameter.
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| public interface IRememberMostRecent<T>{ void Remember(T thingToRemember); T TellMeMostRecent(); List<T> PastThings { get; }} |
When a class implements this interface, it can choose to fully construct the interface (provide a type).
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| public class Farmer : IRememberMostRecent<Joke>{ public string Name { get; protected set; } public Farmer(string name) { Name = name; lastJoke = null; allJokes = new List<Joke>(); } // IRememberMostRecent implementation private Joke lastJoke; private List<Joke> allJokes; public void Remember(Joke jokeToRemember) { if (lastJoke != null) allJokes.Add(lastJoke); lastJoke = jokeToRemember; } public Joke TellMeMostRecent() { return lastJoke; } public List<Joke> PastThings { get { return allJokes; } }} |
Using the Farmer class:
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| Farmer burton = new Farmer("Burton");burton.Remember(new Joke("A man walks into a bar.", "Ouch"));burton.TellMeMostRecent().Output();burton.Remember(new Joke("What's red and invisible?", "No tomatoes"));burton.TellMeMostRecent().Output(); |