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In this video, we'll review the solution to the first challenge and introduce our second challenge—instantiating instances of the classes that we created in the first challenge.
Instructions
2nd Challenge
- In the Program.cs file
Main()method, use thenewkeyword to create at least one instance of each of your media type classes. - For each of the objects that you create, set each field to an appropriate value.
Help
If you get stuck on any of the following topics or simply need a refresher, click on a topic in list below to view the associated video in the C# Objects course.
Welcome back, how did it go?
0:00
It's okay if you weren't unable to
complete every part of the challenge.
0:02
It's not unusual to struggle when
you're learning something new.
0:05
Let's walk through my solution.
0:09
I started by adding a .cs file for
each of my media types.
0:10
Remember that it's a convention for
the file name to match the class name.
0:15
So File > New File then Album.cs.
0:20
Then File > New File, Book.cs.
0:27
And then File > New File,
again, and Movie.cs.
0:34
In the Album.cs file, I then added
the Treehouse.MediaLibrary namespace.
0:41
Then, within the namespace code block,
I added the class definition.
0:53
The class keyword, followed by
the name of the class, Album, and
0:58
a set of curly braces.
1:02
To save a bit of typing, I copied and
pasted this code into the other files,
1:07
And changed the class name to
the correct name for that file.
1:15
Then I added the fields to each class.
1:24
For the Album class, I added Title and
Artist fields, both of type string.
1:29
So public string Title,
then public string Artist.
1:34
Each of my media types has a Title field,
so
1:41
I'm going to copy this line
of code to the clipboard.
1:45
Then in Book,
I'll paste that line of code, And
1:49
add one more field, public string Author.
1:53
Then in the Movie class,
I'll paste from the clipboard again and
1:59
add the second field,
public string Director.
2:03
Once I finished writing the code for
the classes, I open the console and
2:09
use the mcs command to compile my program,
2:13
just to make sure that I didn't
make any mistakes in my code.
2:16
mcs, and then I'll use *.cs to include all
of the .cs files in my project's folder.
2:20
And I'll include -out:Program.exe,
2:27
which is the name of the exe file
that I want the compiler to create.
2:31
All right,
I didn't receive any compiler errors, so
2:43
it looks like I didn't make any mistakes,
at least so far.
2:46
I did receive some warnings, but that's
because we're not using the media type
2:49
classes and
setting any of the field values.
2:54
Let's fix that now.
2:57
Remember that a class is a template for
2:59
making individual objects
of a particular type.
3:01
For example, using the Album class,
I can create three objects, or
3:04
instances, of the Album class.
3:09
For the second challenge, use the new
keyword in the Program.cs file Main
3:11
method to create at least one instance
of each of your media type classes.
3:15
Then, for
3:21
each of the objects that you create,
set each field to an appropriate value.
3:22
I created three media types,
so I'll create or
3:27
instantiate an instance of the Album,
Book, and Movie classes.
3:30
Then for the Album class instance, I'll
set values on the Title and Artist fields.
3:36
And for the Book class instance, I'll set
values on the Title and Author fields.
3:42
And for the Movie class instance, I'll set
values on the Title and Director fields.
3:48
And that's it for the second challenge.
3:53
After the break,
I'll show you my solution.
3:55
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