Generics Part I

• Generics allow us to create and use strongly type collections that are type-safe because we do not need to do casting of the elements nor do boxing and unboxing of  value types. 
• Generic classes is defined including the parameter type T in the declaration of the class or interface. 

How to create a generic class

• Add the type parameter T between symbol minor  and  major ( < >) after the class's name.
• Use the type parameter T instead the  data  type names in the  member classes. 

• Each instance of T inside the class is replace with parameter type  that we have provided.
• Specify the type that we want to pass as parameter type.

For example

In this example our list only allow object of type person if we want of other type we can create other list.

• One of the more commons and important use of the generics are in collection classes..

advantages of generics

The generic collections provide :

• Type safety: assure that we have a homogeneous  collection,
• No casting: Casting is very expensive while generics improve the performance the application because add or read items do not need to do casting.
• No boxing and unboxing: they are long expensive and can make slow an application, specially in long collections

Generic list Collections .

Generic  class  list store collections in objects of type T

• List<T> : It is a list of generic use
• LinkedList<T>:it is list in which each item is linked  to previous  item  and the next in the collection.
• Stack<T>: it is a collection last in, first out
• Queue<T>: it is a collection first in, first out

Generic Dictionary collections  

It is dictionary classes that store pair key and value.

the key and the value are strongly types

• Dictionary<Tkey, TValue>:it is a generic dictionary to use general.
• SortedList<Tkey,TvalueZ>:
• SortedDictionary<TKey,Tvalue>: They are sort collections by  key