What are Generic Collections in C#? [duplicate]

Answer 1

You need to substitute T for another Type such as int, string or a class of your creation:

List<int> values = new List<int>();

values.Add(1);
values.Add(2);

int secondNumber = values[1]; // Yay! No casting or boxing required!

Answer 2

When you do a List<Object>, make sure your Object class is public. In default VS installations, classes come out of the box as 'internal' - meaning you can't make a list of them because they're less accessible than the public List you're declaring.

This got me um... yesterday. Stupid defaults.

Answer 3

Consider T as a variable name. You must specify its value, ie. make the generic class 'specific'. So, you can create List<string>, List<int>, or List of anything else you want.

Answer 4

For example if you wanted a generic list of integers (int) you would write:

List<int> list = new List<int>();

T is a type parameter, that in your code should be an actual type.

Answer 5

You declare a List of Foo objects like so:

List<Foo> fooList;

The in the type name is a placeholder for the 'real' type of object you put in to the generic list at the time you instantiate it.

Answer 6

Are you trying to use the List class or are you trying to build your own? What does your code look like at the moment?