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Introduction to
Programming: Java
Learning to Program Robotically
INSTRUCTOR: Craig Duckett
EMAIL: [email protected]
Computer Programming
What is Computer Programming ?
 Computers don't do anything without someone telling them what to do—much like
the average middle school student.
 To make the computer do something useful, you must give it instructions in either
of the following two ways:
 Write a program that tells a computer what to do—step by step—much as you write out
a recipe.

Buy a program that someone else has already written that tells the computer what to
do.
 Ultimately, to get a computer to do something useful, you (or somebody else) must
write a program.
 A program does nothing more than tell the computer how to accept some type of
input, manipulate that input, and spit it back out again in some form that humans
find useful.
Programming is Problem-Solving!
 Essentially, a program tells the computer how to solve a specific problem. Because the world is full
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of problems, the number and variety of programs that people can write for computers is practically
endless.
But to tell a computer how to solve one big problem, you usually must tell the computer how to
solve a bunch of little problems that make up the bigger problem. If you want to make your own
video game, for example, you need to solve some of the following problems:
Determine how far to move a figure (such as a car, a spaceship, or a man) on-screen as.
Detect whether the figure bumps into a wall, falls off a cliff, or runs into another figure on-screen.
Make sure that the figure doesn't make illegal moves, such as walking through a wall.
Draw the terrain surrounding the cartoon and make sure that if the figure walks behind an object
such as a tree, the tree realistically blocks the figure from sight.
Determine whether bullets that another figure fires are hitting the player's figure. If so, determine
the amount of damage, how it affects the movement of the damaged figure, and how the damage
appears on-screen.
The simpler the problem is that you need to solve, the more easily you can write a program that tells
the computer how to work. A program that displays a simple Ping-Pong game is much easier to
write than a program that displays World War II fighter airplanes firing machine guns and dropping
bombs on moving tanks while dodging anti-aircraft fire in a smoke-filled sky.
Programming isn’t Difficult, but Time-Consuming
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Programming really isn't that difficult or mysterious. If you can write step-by-step instructions directing
someone to your house, you can write a program.
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The hardest part about programming is identifying all the little problems that make up the big problem that
you're trying to solve. Because computers are completely mindless, you need to tell them how to do
everything and also how to continue when something unexpected happens. This means thinking through
many “what if” scenarios.
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Like Philosophers and other wooly thinkers, Programmers are constantly asking questions and
considering all the various ifs, ands, and buts of logic and decision-making.
“What if…?”
Philosophers & Programmers
What do they have in common besides pondering and logic?
Everybody else in the world
Philosophers & Programmers
Still …
Even though most of us practice philosophical thinking and the
components of logic and decision-making hundreds of times a day …
… we just don’t do it for a living or make a career out of it.
And why?
Most people are not “cut out” to be philosophers or programmers.
Most people don’t “get” whatever it is that philosophers and
programmers “get” and it is for this reason, most people are not
philosophers or programmers.
Philosophers and programmers are a rare and often solitary breed.
Now, going forward, let’s consider Logic thinking & Decision-Making …
Logical Thinking
But First, A Simple Puzzle
Can you make a necklace that
costs no more than 15 cents using
the four chains below?
It costs 2 cents to open a link and
3 cents to close it again.
If you're like most people, you'll
be blind to the correct answer
because you'll become fixated on
the
answer
that
seems
immediately logical.
But immediate logic might not
always be the best path of action.
But First, A Simple Puzzle
1
2
Immediate logic might suggest that we line up the
four chains like this and open and close a link at
each other four corners, but this won’t work
because 4 (corners) x 2 (open) x 3 (close) = 20, and
we only have 15 cents.
The trick is to come up with a way where we can do
3 x 2 x 2 = 15.
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Luckily, there is.
Instead of looking at the number of chains, we
might look at the number of links in one chain.
A Simple Solution
If we were to open all the links in a single
chain that would cost use 6 cents, leaving
9 cents remaining for closing the links, for
a total of 15.
A Simple Solution
1
2
Now we have three chains with three
corners, and three separate links to create
the necklace.
3 (corners) x 2 (open) x 3 (close) = 15
Problem solved!
3
Decision Making
Now, A Simple Scenario…
Game’s on at
my house.
Beer’s cold!
B
The Task: Directions
1. Go from Point A to Point B
Dude, I’ll be
right over!
A
…Where Things Could
Go Wrong …
B
The Task:
1. Go from Point A to Point B
2. Watch for passing cars at the
Intersections
OR
3. Treat Intersections as 4-Way
Stops
A
Decisions, Decisions …
B
The Task:
1. Go from Point A to Point B
2. Stop at all Intersections (2-way
stops going North and South)
3. Watch for cars going West and
East before going through the
Intersections.
A
Different Decisions
NOT Based on Directions…
B
The Task:
1. Go from Point A to Point B
2. Treat Intersections as 4-Way
Stops
3. Consider rules of “Right of
Way” before going through
the Intersection
a) Car to left
b) Car to right
c) Car ahead, not turning
d) Car ahead, turning
4. Unexpected things:
IF / ELSE / OR / AND
A
More Decisions …
B
The Task:
1. Go from Point A to Point B
2. Treat Intersections as 4-Way
Stops
3. Consider rules of “Right of
Way” before going through
the Intersection
a) Car to left
b) Car to right
c) Car ahead, not turning
d) Car ahead, turning
4. Unexpected things:
IF / ELSE / OR / AND
A
Alternative Decisions …
The Task:
1. Go from Point A to Point B
2. Treat Intersections as 4-Way
Stops
3. Consider rules of “Right of
Way” before going through
the Intersection
a) Car to left
b) Car to right
c) Car ahead, not turning
d) Car ahead, turning
4. Unexpected things:
IF / ELSE / OR / AND
B
Different Decisions …
B
The Task:
1. Go from Point A to Point B
2. Consider rules of “Green / Red /
Yellow ” before going through
the Intersection
a) Red - STOP
b) Green - GO
c) Yellow - CAUTION
3. Unexpected things:
IF / ELSE / OR / AND
A
Unexpected Decisions …
B
The Task:
1. Go from Point A to Point B
2. Consider rules of “Green / Red /
Yellow ” before going through
the Intersection
a) Red - STOP
b) Green - GO
c) Yellow - CAUTION
3. Unexpected things:
IF / ELSE / OR / AND
Tree Across Roadway
Power Lines Across Roadway
Gravel in Roadway
Glass/Metal in Roadway
A
Different Decisions …
The Task:
1. Go from Point A to Point B
2. Consider rules of “Green / Red /
Yellow ” before going through
the Intersection
a) Red - STOP
b) Green - GO
c) Yellow - CAUTION
4. Unexpected things:
IF / ELSE / OR / AND
A
Programming is All About Decision Making, Logic, & Memory
Do … While
If … Then
Or … Else
And … Or
True … False
… Fail Gracefully
and Meaningfully
All this DECISION MAKING
has to be STORED and
TRACKED somewhere!
…And Avoiding Errors/Crashes/Blue Screens
The dreaded “Blue Screen of Death”
But How Does It All Work?
 Central Processor Unit (CPU)
 Memory
 Storage
 Input/Output (I/O)
 Keyboard
 Mouse
 Monitor
 Speakers
 Network
Memory
 RAM (Random Access Memory)
 DRAM (Dynamic)
Memory Storage Cells
"Allocated Memory Locations"
http://static.howstuffworks.com/flash/ram-virtual.swf
Memory  Text Characters
ASCII (American Standard Code for Information Interchange)
Play Video
Java  Memory
Throughout the quarter, instead of calling these by their correct name,
Allocated Memory Locations, I will usually just called them "Buckets".
Programming Paradigms
 Procedural (Top Down “Function” Driven)
 Object Oriented (“Class” and “Object” Driven)
Procedural Programming
Programs in the past used a procedural process for development where a
program performed in series of steps , in a linear fashion and the focus was
on steps as shown below:
Object-Oriented Programming
In object-oriented programming, the focus is on real world objects which
interact with each other. Objects in turn have state, attributes and
operations. Objects are viable things that do something. Objects perform
actions.
Class , Object, and Method:
Here Comes the Hippy-Dippy Stuff!
Objected-Oriented Programming:
Three Important Terms
• Class – A template or blueprint which defines attributes and actions
(properties and behavior). It is like the ‘idea’ of a thing, but not the actual
thing itself. Example: a blueprint of a house is not something you can live
in, but you can use the blueprint to construct a house.
• Object – Something that is created (instantiated) from the Class
blueprint or template. Example: A house constructed from a blueprint
that you can actually live in would be an Object
• Method – The action or behavior that an Object can do as defined by
the Class. Example: You can fly a plane (an Objected made from the Plane
class), but you cannot fly a car (an Object made from the Car class)…at
least not yet!
Class
A “Class” is the idea of how something might look or what something
might do
Class Car
A Class “Car” will have some ideas as to how a car should look and
what it might do. We will have to come up with these ideas…
Class Car
fourWheels()
oneSteeringWheel()
oneEngine()
twoOrFourDoors(?)
twoOrFourSeats(?)
transmissionType(?)
You can create methods that will define how a “car” might look and
what it might do.
Class Car
fourWheels()
oneSteeringWheel()
oneEngine()
twoOrFourDoors(?)
twoOrFourSeats(?)
transmissionType(?)
myCar
Now you can create an Object from the Car class that can use the Car
methods to look a certain way and do certain things as defined by the Car class.
Class Car
fourWheels()
oneSteeringWheel()
oneEngine()
twoOrFourDoors(?)
twoOrFourSeats(?)
transmissionType(?)
myCar
myCar.fourWheels()
myCar.oneEngine()
myCar.twoOrFourSeats(4)
myCar.oneSteeringWheel()
myCar.twoOrFourDoors(4)
myCar.transmissionType(auto)
Now you can create an Object from the Car class that can use the methods
so it can look a certain way and do certain things as defined by the Car class.
Class: Example Using Language
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•
•
•
•
•
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Animal
Mammal
Breed
Fur
Barks
Plays fetch
Digs
Chase cats
Eats
Sleeps
Etc. …
Class: Example Using Language
The word "animal" comes from the Latin word animalis, meaning
"having breath". The biological definition of the word refers to all
members of the kingdom Animalia, encompassing creatures as
diverse as fish, reptiles, birds, mammals, and insects .
Mammals are air-breathing vertebrate animals characterized
by the possession of endothermy, hair, three middle ear bones,
and mammary glands functional in mothers with young.
•
•
•
•
•
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Animal
Mammal
Breed
Fur
Barks
Plays fetch
Digs
etc …
From Consensus  Class  Object
We think in terms of “Class” all the time …
For instance, do you understand this sentence?
The dog chased the ball into the street and nearly got hit by the car.
Okay, if you understand this sentence, then …
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•
•
•
What kind of dog was it?
What kind of ball was it?
What kind of street was it?
What kind of car was it?
“Class”  Objects
“Dog”
“Ball”
General Attributes
General Attributes
General Attributes
General Attributes
Specific Properties
and Actions
Specific Properties
and Actions
Specific Properties
and Actions
Specific Properties
and Actions
“Street”
“Car”
Class  Object
In Object-Oriented Programming, a Class is like a cookie cutter and type of
dough, and Objects are like the actual cookies made from them.
In this example, the cookie cutter and dough make up the Class which
supplies specific attributes like type of dough, shape, and size.
Any cookie made from this Class is an Object and will inherit the attributes
as defined by the Class (i.e., type of dough, shape, and size).
Class  Class  Object
PersonWithCapAndBag EXTENDS Person
In Java, the various things (actions) that Objects do are called Methods
Objects Do Something (Some Action)
In Java, the various
things (actions) that
Objects can do are
called Methods
Object & Method: Dot Notation
Mailman.fillBag();
Mailman.deliverMail();
Mailman.pickUpMail();
Mailman.putMailInBag();
Mailman.runFromBigDog();
Object
Method
Paperboy.fillBag();
Paperboy.deliverPaper();
Paperboy.runFromBigDog();
Paperboy.drinksSlurpee();
Paperboy.collectsPayment();
Object
Method
Methods are part of the Class from which the Objects are made
(or instantiated in programming terms). Methods are referenced
by a name with double paretheses ( ) at the end.
So, Putting it All Together…
In Java, we will be doing using Classes, Objects, and
Methods to code programs
•
Class A class is the blueprint (containing attributes and actions) from
which individual objects are created
•
Object An object is a named instance of a class that can now actually
do something
•
Method A method is an action from a class that the object might do
DON’T WORRY: We will “officially” be going over Classes, Objects, and Methods again in
the next Lecture, so don’t fret if this is a little confusing today. It will all start to sink in, I
promise, and we’re going to have a lot of fun with it 
What you will learn in this Introduction to Programming class is just the
"tip of the iceberg" but it will establish a firm foundation for you to
confidently go on to learn and excel in other programming languages.
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