Can anybody give a good example of what to use generic classes for?

Question

We recently learned about generic classes in C#, but our teacher failed to mention what they can be used for. I can't really find any good examples and would be extremly happy if somebody help me out :)

Have you made your own generic class, and what did you use it for?

Some code examples would make me, and my classmates, really happy! Pardon the bad english, I am from sweden :)

happy programming!

Sorry- I think I could have written the question a bit better. I am familar with generic collections. I just wondered what your own generic classes can be used for.

and thank you for the MSDN links, I did read them before posting the question, but maybe I missed something? I will have a second look!

Answer 1

Generic Collections

Generics for collections are very useful because they allow compile time type safety. This is useful for a few reasons:

• No casting is required when retreiving values. This is not only a performance benefit but also eliminates the risk of there being a casting exception at runtime

• When value types are added to a non generic list such as an ArrayList, the value's have to be boxed. This means that they are stored as reference types. It also means that not only does the value get stored in memory, but so does a reference to it, so more memory than necessery is used. This problem is eliminated when using generic lists.

Generic Classes

Generic classes can be useful for reusing common code for different types. Take for example a simple non generic factory class:

public class CatFactory
{
  public Cat CreateCat()
  {
    return new Cat();
  }
}

I can use a generic class to provide a factory for (almost) any type:

public class Factory<T> where T : new()
{
  public T Create()
  {
    return new T();
  }
}

In this example I have placed a generic type constraint of new() on the type paramter T. This requires the generic type to contain a parameterless contructor which enables me to create an instance without knowing the type.