CSIS 110 – Lecture 9
Reading: finish chapter 3
Quiz Results
Mean: 21.5 Median: 22 Max: 25
Distribution: <17.5: 1 17.5 – 19.5: 1 20 – 22: 7 22.5 - 24.5: 5 25: 3
Last Time
- Constructor overloading
- Internal and External method calls
oInternal: Method in same class. Call it implicitly on the current object.
oExternal: Method in a different class. Call it using an object (not the class)
Discuss indenting w/ if statements.
Mail-System
Show how the mail-system project works.
Now, go ahead and open this project and try it yourselves.
There are three classes in this project: MailItem, MailClient, and MailServer
- MailItem is fairly simple
- We’ll look at MailClient in more detail
- MailServer is more complex – I won’t be talking about it in detail. We can see
that it works to send messages (as MailItems) from one MailClient to another. We
don’t HAVE to know how it works – another benefit of abstraction.
The this keyword
Let’s look at the MailItem class. Look at the constructor – is there something new?
this.from = from;
What kind of statement is this?
It’s an assignment – it assigns the value of the LHS (from) to the RHS (this.from).
What’s going on? What is the name of the formal parameter in the constructor? What is
the name of the instance variable? Oops! They have the same name! This is called name
overloading.
So, while constructor is executing, there are 6 variables [Draw pix].
