Eboard 17: Iterators
You are probably being recorded, perhaps even transcribed.
Approximate overview
- Administrivia
- Questions
- Lab
Preliminaries
- I’ve revised my target for returning the first set of LAs. (Tonight.)
- There is no reading for Friday.
- Those of you planning to declare CS majors should make sure to fill
out the form by 5pm today.
- If you don’t fill out the form, you won’t get an advisor.
- If you don’t get an advisor, you won’t be able to declare a CS major.
- If you don’t declare a CS major, you probably won’t be able to take
any more CS classes.
- Please try to use realistic examples rather than contrived ones.
- Please cite carefully. I saw code from labs, which suggests that it
was done with someone else, that was not cited.
- Make sure to include code. I will not follow links when grading.
- Don’t grab code from random places on the Interweb.
- If you can’t click the academic honesty statement, we should chat. You
can find another example to use.
- Please don’t include your name in LA answers.
Code concerns
- Do not use double values for values that should be exact.
int or long values are exact. double values are not.
- Do not print error messages from utility functions.
- Return a special value.
- Use exceptions.
- Please follow Java standards. For example, capitalize class names.
- Please don’t double-space your code. (Yes, it happens when you copy
and paste from some applications. You are prospective computer science
majors; you should be able to figure out how to deal with the issue.)
Encapsulation
- Two key concepts, which are … TPS.
- Limit access to the internal structure of the object (i.e., the
fields) so that client codes doesn’t change things unexpectedly.
- We may have expectations about the state of the fields; this can
lead to crashes.
- We can change the implementation without affecting the client
code.
- All the code and fields that go together are in one thing (class).
- Also
- This also helps us separate our code.
- As designers, we can abstract away a bit. (Abstraction means that
client coders can see what we do without knowing how.)
- Protect patent rights.
- Protect ourselves from being made fun of.
- Why doesn’t Sam like the following/why won’t he give it credit? (More TPS)
public class Monkey {
/**
* The monkey's name.
*/
private String name;
/**
* The monkey's age.
*/
private int age;
/**
* Build a new monkey.
*/
public Monkey(String name, int age) {
if (this.age < 0) {
System.err.println("Invalid age!");
}
if (null == this.name ) {
System.err.println("Invalid name!");
}
this.name = name;
this.age = age;
} // Monkey(String, int)
/**
* Get the name.
*/
public String getName() {
return this.name;
} // getName()
/**
* Set the name.
*/
public void setName(String newName) {
this.name = newName;
} // setName(String)
/**
* Get the age.
*/
public int getAge() {
return this.age;
} // setAge()
/**
* Set the age.
*/
public void setAge(int newAge) {
this.age = newAge;
} // setAge(int)
} // class Monkey
- The object doesn’t really have any purpose other than storing two
values. (Encapsulation doesn’t serve the programmer here.)
- We could get rid of the
setAge function.
- Printing error messages is awful. And we still return an object from
the constructor.
Subtype polymorphism
- Is not the same as inheritance.
New LAs
- I’ve released a bunch of new LAs as well as opportunities for
redos of the prior LAs. (I realize you may not get the originals
in time to redo. However, not all of you submitted them in the
first go-round.)
- One LA is not like the others (ADT design/PUMishment). This one asks
you to do something new. But you have from now until Friday to do it.
- If there’s ever an LO for which you want me to release an LA, let me
know.
New MP
- Borrowed from elsewhere and then updated.
- We’ll look at it together.
Upcoming work
- Wednesday, 2024-02-28, 11pm, MP4
- Friday, 2024-03-01, 1pm: Submit Today’s Lab
- Friday, 2024-03-01, 11pm, Submit the second set of LAs.
- Sorry, no Gradescope links; there are too many
- Friday, 2024-03-01, 11pm, MP4 post-reflection
- Friday, 2024-03-01, 11pm, MP5 pre-preflection
Tokens
Academic/Scholarly
- Thursday, 2024-02-29, 11:00-noon, HSSC Auditorium
Scholars’ Convocation: Peter Michael Osera Grinnell Talk
- Tuesday, 2024-03-05, noon, Some PDR.
CS Table.
- Tuesday, 2024-02-27, 8:00–9:00pm, Science 3821.
CSC-207 Mentor Session.
Cultural
- Monday, 2024-03-04, Sebring Lewis.
Des Moines Metropolitan Opera: Beauty and the Beast
- Thursday, 2024-03-07, JRC 101, 8:00-9:30 pm.
Writers@Grinnell: Carl Phillips
- Thursday–Saturday, 2024-03-07 to 2024-03-09, 7:30 p.m.
Songs of the Scarlet and Wayback (play).
- Saturday, 2024-03-09, Harris Cinema, ??:??
Met Opera: Verdi’s La Forza del Destino.
Peer
- Saturday, 2024-03-02, ???, either at the Tennis Courts are in the Field
House.
_Tennis (men’s and women’s)
- Saturday, 2024-03-02, 2pm, in Sebring Lewis.
Orchestra, Bartok. Vegetables. More!
Wellness
- Friday, 2024-03-01, 7pm in JRC 101.
Spa Night.
- Tuesday, 2024-03-05, noon-1pm, BRAC P103.
HIIT and Strength Fitness Class.
- Tuesday, 2024-03-05, 12:15–12:50, Bucksbaum 131.
Yoga in the Museum.
- Tuesday, 2024-03-05, 4pm, BRAC P103 (Multipurpose Dance Studio):
Yoga.
Misc
Other good things to do (no tokens)
Questions
MP4
The specifications said that we should return false when remove is
called with a key not in the array, but one of the unit tests tests to
see if remove throws an exception in that case. What should I do?
Ignore the failed test. Maybe Self-Gov the failed test.
The specifications said that we should not test the toString method.
However, I see some tests of the toString method, including one by my
instructor. What should I do?
Praise your instructor for writing such an amazing test.
Administrative
LAs
Iterators
In the ArrayBasedStack example, if the underlying array is private, what
do we do? Can we still have a link to the Stack or need we link to the array?
I’ll chat with you about it after class.
Other topics
Lab