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[MUSIC]

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Hi There.
This is James.

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In this C# practice session, you'll
practice class inheritance using C#.

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It reinforces what you learned in
stage three of the C# objects course.

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If you find this practice session
too challenging to complete,

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you might need to review that course.

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See the teacher's notes for a link.

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This practice session is
the third in a series of sessions

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where you'll build out a media
library console application.

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Step-by-step you'll add
features to the program.

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Eventually, you'll be able
to use C# to add, list, and

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search for items like albums, books, and

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movies, whatever you want to have
catalogued in your media library.

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In previous practice sessions, we
defined the attributes and behaviors for

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our program's media type objects by
adding class fields and methods.

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In this practice session, we'll see how
we can use class inheritance to extend

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to all of our immediate
type classes the behaviors

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that we currently have defined in
just a single media type class.

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Go ahead and open your workspace
from the previous practice session.

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Or you can open the workspace
that I've attached to this video.

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If you want, you can download the project
files in order to use an external editor

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or an IDE like Visual Studio.

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In the last practice session, we added
behaviors to our album media type class.

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But really, these behaviors or

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methods should be available
on all of our media types.

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We could copy and paste these methods to
each of our other media type classes.

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This wouldn't be too much
work given that we currently

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only have two other media type classes.

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But what if we had five or
ten media type classes?

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Not only would this be a lot
of extra work, in general,

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we should strive to
avoid code duplication.

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Unnecessarily duplicating
this code could make

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future maintenance on these
classes more difficult to manage.

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So let's practice using
object oriented programming

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in order to keep our code clean,
concise, and easier to maintain.

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Remember from the C# objects course
that classes define what it means to be

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in a particular classification.

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The album, book, and

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movie classes are all representations
of their real life counterparts.

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They're also subclasses of a more
generalized classification.

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Specifically, they're all media types.

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We need to create a media type base class.

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Then we can update our media type
subclasses to inherit from the media

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type base class, allowing them
to inherit the attributes and

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behaviors from the more
generalized base class.

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For your first challenge, you'll add
a MediaType base class to your program.

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Within that class, you'll define a public
filed named Title of type string,

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and you'll add a constructor that
defines a parameter named title,

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again of type string, that you'll
use to initialize the Title field.

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After adding the base class, you'll update
your existing media type classes to

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inherit from the MediaType base class.

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Then, from each of these
media type subclasses,

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you'll call the base class's constructor.

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Lastly, you'll review your
media type subclasses, and

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remove any title field
definitions from those classes.

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You'll also remove from
the constructors in those classes,

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any related field initialization code.

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And that's your first challenge.

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Don't worry if you aren't able to
complete every part of this challenge.

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Complete as much of it as you can, and in
the next video, I'll show you my solution.

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Good luck, and
we'll see you in just a bit.