Transcript Document

CS110
Introduction to Programming
Lecture 1
January 27, 2004
Ethan Bolker
• Philosophy
•Bank: user interface, Java, object model
• Programming environment
• Homework 1
• Start now!
Announcements
• These slides are available on course web page
• Hand in questionnaire on your way out
• Discussion sections meet regularly in Purple
Lab, upper garage level in Healey library
• Purple lab PCs have been configured for CS110
• Other lab computers will be ready soon – I will
let you know when
• Passwords for homework turnin web site
available at next class
Lecture 1
2
Learning to program
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Lots of fun
Practical
Hard, time consuming
Unusual mixture:
– sophisticated intellectual content
– picky details that must be right
• Exercise in reading, writing, thinking
• CS110 is for CS majors, future professionals
Lecture 1
3
Teaching/learning style
• To learn a language well, live in a land where
it’s spoken – anxiety producing, but efficient!
• Learn to write by to reading and writing and
writing about what you learn
• 60% of a lot is more than 100% of a little
• Ask questions (to slow me down)
Lecture 1
4
Computers and programs
• Computer: a machine that can simulate many
different machines
word processor
internet shopping site
traffic light controller
bank ATM
…
• Program: the instructions that tell a computer
how to act like some particular machine
• Example: Bank simulation
– user interface (how the program behaves)
– object model (the program’s architecture)
– Java implementation (the program itself)
Lecture 1
5
Bank simulation - user interface
a:\> java Bank [Enter, CR]
Welcome to Engulf and Devour
Account number (1 or 2), 0 to shut down: 1
Transactions: exit, help, deposit, withdraw, balance
transaction: balance
200
transaction: deposit
amount: 799
transaction: balance
999
transaction: exit
Account number (1 or 2), 0 to shut down: 0
Goodbye from Engulf and Devour
a:\>
Lecture 1
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Bank simulation - object model
program architecture
Bank
“Engulf and Devour”
BankAccount
String
int
int
balance: 200
999
bankName:
BankAccount
account1:
BankAccount
BankAccount
account2:
Terminal
int
balance: 200
200
Terminal
atm:
Lecture 1
7
Why Java?
• Fashionable, modern (for good reasons)
• Object oriented: when you have designed
the architecture a program almost writes
itself
• Portable: the same Java code turns any
computer (PC, mac, server) into a Bank
• Well designed:
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consistent user interface
easy to learn
hard to make serious mistakes
prebuilt objects plug into your programs
Lecture 1
8
Send object a message
Bank.java (lines 101ff)
while ( moreTransactions ) {
...
String command = atm.readWord( "transaction: " );
...
else if ( command.equals( "deposit" ) ) {
int amount = atm.readInt( "amount: " );
account.deposit( amount );
}
...
else if ( command.equals( "balance" ) ) {
atm.println( account.getBalance() );
}
...
}
object dot message ( information )
Lecture 1
9
Bank simulation
Objects responding to messages
Terminal object (the atm)
message from Bank:
readWord(″transaction: ″)
line 107
command customer typed
return info to Bank
String object (the command)
equals(″deposit″)
line 114
true or false
Lecture 1
return info to Bank
10
Bank simulation
Objects responding to messages
BankAccount object
message
from Bank:
before
deposit(799) bal: 200
after
return info to
Bank:
bal: 999
line 116
getBalance()
line 123
bal: 999
bal: 999
Lecture 1
999
11
Software development cycle
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imagine
design
edit
compile
run, test
imagine the
next release ...
• user interface
• object model
• Java implementation
X
E
m
a
c
s
• quality assurance
• good programs evolve!
Lecture 1
12
emacs
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The programmer’s editor (word processor)
Learning emacs is as important as learning Java
You will live inside emacs in this course
XEmacs installed on all lab PCs,
available free for home machines
• Start using it today – tutorial linked from course
home page
Lecture 1
13
Homework 1
• Handed out in class, on course web page
• Part 1 – get started
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Hard copy due at the next class
Send email
Explore course web page
Understand rules about honesty
Write about what you find – use emacs
• Part 2 - jump in to Java
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Collected electronically Tuesday Feb 3
Play with Bank simulation
Improve Bank simulation
Write about your coding and testing
Lecture 1
14
Start now!
• Turn in questionnaire as you leave class
• Sections meet in Purple lab (Library upper level)
• Today: begin hw1
– send email! (any lab)
– explore web page www.cs.umb.edu/cs110 (any lab)
– begin using XEmacs (Purple lab)
• I will be in my office (S-3-179) today until 4,
tomorrow 12-2:30
Lecture 1
15