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In this video, we'll review the solution to the second challenge and introduce our third and final challenge—adding a method overload.
Instructions
3rd Challenge
- Add a method overload for the
Loan()method that doesn't accept any parameters. - Update the
GetDisplayText()method to account for when theLoaneefield doesn't have a value.
Addition Assignment Operator (+=)
For more information about the addition assignment operator (+=) see https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/addition-assignment-operator.
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.
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How did it go with the second challenge?
0:00
Let's walk through my solution.
0:02
In the album class,
I stubbed out the loan and return methods.
0:04
Public void Loan() And
public void Return()
0:08
Since the methods won't be
returning a value to the caller,
0:23
I use the special keyword void for
the method return type.
0:26
To complete the loan method,
I added a string parameter named loanee.
0:32
Defining this parameter
will allow the caller
0:39
to provide the name of the person
who's borrowing the item.
0:42
At this point, I remembered that I needed
to add two new fields to the album class.
0:45
A string field named Loanee And
a bool field namedOnLoan.
0:52
And then, back in the Loan method,
1:05
I set the loanee field to
the loanee parameter value.
1:07
And the OnLoan field to true to indicate
that the item is currently on loan.
1:15
To complete the return method,
1:24
I reset the loan-related fields
to their default values.
1:26
Null for the Loanee field And
false for the OnLoan field.
1:29
To indicate that the item was
returned to the media library.
1:37
A quick note about the default values for
the Loanee, and OnLoan fields.
1:45
The default values for
these fields work for
1:50
our needs when an item is initially
created and added to the media library.
1:52
It shouldn't have a Loanee field value.
1:57
And the OnLoan field should be
set to false, given that we
2:00
don't need to initialize these fields to
something other than their default values.
2:04
Stylistically, you could explicitly
set them to their default values.
2:09
Doing that might make
your intentions clearer
2:14
to anyone else who's reading your code.
2:17
If you like, you can set explicit default
values here where the fields are defined.
2:24
Or you can do that in the constructor.
2:29
But for now, I'm just going to let
the default values to be set implicitly.
2:32
Continuing on.
2:40
In the GetDisplayText method,
2:41
I updated it to include the loan related
fields if the item is out on loan.
2:43
I started with declaring
a string variable named text.
2:53
For the text to return instead of
immediately returning it from the method.
3:00
Then, I added an if statement in
order to check if the OnLoan field
3:05
is set to a value of true.
3:09
If OnLoan, then a set of curly braces.
3:11
And if the OnLoan field
value evaluates to true,
3:17
I appended the following
text onto the text variable,
3:23
text = text + " (Currently on loan to
3:29
Loanee, And then a close parenthesis.
3:36
You could also use the addition
assignment operator here.
3:42
This operator says add the text
variable to this string value, and
3:49
assign the result back
to the text variable.
3:54
You'll see this approach used frequently
when a string needs to be appended
3:58
to another string.
4:01
And don't forget to
return the text variable.
4:04
To test my changes, I updated
the Program.cs file to call the loan and
4:09
return methods.
4:14
Let's first write the media type
information to the console,
4:17
then loan out the first album.
4:21
Remember, we need to pass the name
of the loanee to the method call.
4:26
How about Joe Smith?
4:30
Then, let's write the media
type information for
4:34
album1 to the console again.
4:36
And then, let's return the album.
4:39
Album1 Return.
4:42
And one more time.
4:46
We'll write the media type information for
the album to the console.
4:48
And lastly, I compiled and
ran the program.
4:51
Here, we can see the display text
before the item was loaned out.
4:59
And then,
when the item was loaned to Joe Smith.
5:05
And here's the display text
after the item was returned.
5:09
Looks like everything
is working as expected.
5:14
For the third and
5:17
last challenge in this practice session,
let's make it possible to indicate that
5:18
something is on loan without having
to supply the loanee's name.
5:22
To do this, you'll add a method
overload for the loan method.
5:26
The current method accepts
a Loanee parameter, so
5:30
you'll add a method overload with a loan
method that doesn't accept any parameters.
5:33
Also, update the GetDisplayText()
method to account for
5:39
when the Loanee field
doesn't have a value.
5:42
And that's it for the third challenge.
5:45
We'll see you in a bit.
5:47
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