Why use "IList" instead of "List"?

Asked Sep 28 '16 at 19:03

Active Sep 28 '16 at 19:09

Viewed 1,353 times

Suppose I have this Student class:

public class Student
{
    public int StudentID { set; get; }
    public string StudentName { set; get; }
    public int Age { set; get; }
}

I like to create collections of Students using List:

List<Student> studentList2 = new List<Student>() { 
   new Student() { StudentID = 1, StudentName = "John", Age = 18 } ,
   new Student() { StudentID = 2, StudentName = "Steve",  Age = 15 } 
};

But I've heard that it's usually better to use IList:

IList<Student> studentList1 = new List<Student>() { 
    new Student() { StudentID = 1, StudentName = "John", Age = 18 } ,
    new Student() { StudentID = 2, StudentName = "Steve",  Age = 15 }
};

I don't understand why people recommend using IList<Student> instead of List<Student>!

Is it some kind of performance concern? Is it optional and down to personal preference? Or is there another reason?

edited Sep 28 '16 at 19:09

Kevin

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asked Sep 28 '16 at 19:03

amin sedaghaty

http://stackoverflow.com/questions/17170/when-to-use-ilist-and-when-to-use-list – Sajeetharan Sep 28 '16 at 19:04
See also https://stackoverflow.com/questions/8717582/why-use-ilist-or-list – Peter Duniho Sep 28 '16 at 19:04
Specifying the interface instead of the implementation allows you to change the type of list later, and you won't need to go around changing everything down the road. – Carcigenicate Sep 28 '16 at 19:08
can u show me with a example? – amin sedaghaty Sep 28 '16 at 19:12

Why use "IList" instead of "List"?

0 Answers0