Object-Oriented Design and
Programming II
CS262
Finite State Machines
Getting Oriented
•
Visit the class web page to access the syllabus, slides, handouts, and
grades.
–
http://www.uwosh.edu/faculty_staff/huen/262/s10262.htm
- Pick up code handouts from the shared drive on the Novell network (Soft
Q drive): For example:
–
•
Submit your work to the shared drive: For example:
Q:\Shared\Huen\262\Submit\Lab01\
Read the UWO Student Discipline Code (UWS 14) at
•
–
•
•
Q:\Shared\Huen\262\Labs\S10_Labs
http://www.uwosh.edu/dean/conduct.htm
Textbook companion site: http://cs.armstrong.edu/liang/intro6e/index.html
(The contents of chapters 1 through 6 were covered in CS221)
BlueJ software documentation:
http://www.bluej.org/doc/documentation.html
Object-oriented analysis and
design
For Thursday: Review chapter 7 of our textbook
• Objects
• Each object has a unique identity that
distinguishes it from every other object
Examples: ceiling fan, subway turnstile, gumball
machine, cruise control unit
• Objects have state and behaviors
• What is the state of an object?
• What do we mean by behavior?
Classes
• Similar objects are grouped in a single class
– A class is a template or blueprint for all the objects
that share state and behavior.
– More precisely, instances (or objects) of a class share
the same behaviors and the same set of states they
could be in, but they have a different identity and
(possibly) a different current state.
– UML diagrams are used to specify state, behaviors,
classes, and more.
Finite-state machines
• A UML class diagram is static.
• The UML also has several dynamic
models.
– One of them is the FSM.
FSM = states + transitions (event/action)
• Ceiling fan example:
Pull/change speed
Pull/change speed
Off
Pull/change speed
Pull/changed speed
Low
Med
High
Observation
• A state-transition diagram is a visual
representation of the logic of the FSM
One Java implementation of the
ceiling fan example (Furcy)
Q:\Shared\Huen\262\LectureNotes\F09 Slides\week01
Output in pulling the cord 10 times
Turning slowly
Turning at medium speed
Turning fast
Stopped turning
Turning slowly
Turning at medium speed
Turning fast
Stopped turning
Turning slowly
Turning at medium speed
Discussion
Question: What will happen if you omit one of the
break statements in CeilingFan.java?
Subway turnstile example
• (From Robert C. Martin, Engineering
Notebook Column, June 98)
Coin/unlock
Locked
Unlocked
turn/lock
Exercise: Implement this FSM for next time
Vending Machine Example
A control system has to control the amount of money
dropped into a vending machine. To keep the example
simple, let’s restrict the inputs: only 5 and 10 cent coins
are accepted. The correct, recognized sum is 25 cents.
10
Five
Fifteen
10
5
5
Start
5
5
Stop
10
5
10
Ten
Twen
-ty
A State Machine Diagram for the vending machine counter
Table 1. Transition matrix for the vending machine counter.
Inputs are in the cells
To
Start
Five
Ten
Fifteen
Twenty
Stop
From
Start
-
5
10
-
-
-
Five
-
-
5
10
-
-
Ten
-
-
-
5
10
-
Fifteen
-
-
-
-
5
10
Twenty
-
-
-
-
-
5, 10/change
Stop
-
-
-
-
-
-
Alternative Form of the Transition Matrix
Top row contains input
Other rows are states
Input 5
10
State
Start
Five
Ten
Five
Ten
Fifteen
Ten
Fifteen
Twenty
Fifteen
Twenty
Stop
Twenty
Stop
Stop + change
Stop
Stop
Stop
A Gumball Machine
• States
–
–
–
–
No_quarter
Has_quarter
Sold
Sold-out
• Actions
–
–
–
–
–
Insert_quarter
Eject_quarter
Turn_crank
Dispense
Refill
Finite System Machine for Syllable Recognizer
Not in
VG
Not vowel
Not vowel
VG: Vowel Group
Initial
state
Vowel / count++
In VG
Vowel
Cruise Control as a Finite State Machine
Controls:
ON, OFF buttons.
SET, (DEC, ACC) buttons.
SET / set
current
speed
ON
Ready
Q0
Cruise
ON
Brake
OFF
OFF, SET,DEC,
ACC/ null
How about “decelerate” and “accelerate”?
OFF