AP Computer Science A

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AP Computer Science A

• Jacobson
• Week 1
• Second Semester

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Agenda

• First Semester- Reflections
• Book Check (For Real)
• Marine Biology Case Study
• Chapter 1
• Homework
• First Semester Grades

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Objectives for Today

• Today we will reflect upon the strengths and
  weaknesses of this class last semester, in both a
  verbal and written form.
• You will also observe, report and analyze the
  running marine biology case study.

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Reflection of First Semester

• Fold a piece of paper (that you will turn in) in
  half like a hot dog
• On the left, brainstorm all of the positive
  aspects of last semester.
• On the right, brainstorm all of the roadblocks to
  your learning or things that could be better.

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Share with Class
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Mr. Jacobsons Reflections

• Positives
• Hard work- Diligence
• Problem solving skills are starting to show
• Semester Project

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Mr. Jacobsons Reflections

• Negatives

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Mr. Jacobsons Reflections

• Semester Project
• Great Job following directions
• Needs more work on Object Oriented Programming
  concepts
• Needs more work on algorithms
• Battleship tutorial only helped 1 or 2 groups

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Mr. Jacobsons Reflections

• Places for Change
• More responsive assessments
• More student participation
• Less distractions

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Book Check

• Collect all Simply Java
• Check the number of the other textbook

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Marine Biology Case Study

• What is the purpose?
• Background
• Chapters 1-4 in the Acrobat File for our class
• Getting it running
• Making Observations
• Class discussion

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Marine Biology Case Study

• Getting it running

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Warm up

• Assume that x is an initialized int variable.
  The code segment
• if (x5) x2
• if (x10) x 0
• Is equivalent to which of the following code
  segments?
• x 0
• if (x 5) x 0
• if (x 5) x 2
• if (x 5) x 0 else x 2
• if ( x 5) x 2 else if (x 10) x 0

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Agenda

• Finish Chapter 1 Case Study
• Work together
• Class discussion
• Truth Tables

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Case Study
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(No Transcript)
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Objective-Truth tables

• Today you will make a truth table for a complex
  logical expression and apply that to java
  programming.

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Truth Tables

• What data type is either TRUE or FALSE?
• boolean
• What types of statement evaluate an expression
  that is either TRUE or FALSE?
• if statements
• while loops
• For loops

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Simple Comparisons

• ( total sum )
• (x
• ( str.charAt(0) ! str.charAt(9) )

NOTE Here total, sum and x could be integers or
doubles. str is a String and the method
charAt() returns a character for
comparison. When there is only one comparison in
the whole expression, it is easier to understand
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More Complex- Truth tables can help

• ( (X 20) (X
• statements are true only if both parts are
  true

A B A B T T T T F F F T F
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More Complex- Truth tables can help

• ( (X 20) (X
• statements are true if one or the other is
  true

A B A B T T T T F T F T
T F F F
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More Complex- Truth tables can help

• ( (X 20) ! (X

A B !B A !B T T F F T F T
T F T F F F F T F
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Make a truth table

• Make a truth table for the following expression
• !A !B
• A B !A !B !A !B
• T T F F F
• T F F T F
• F T T F F
• F F T T T

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Equivalent Expressions

• Two expressions are logically equivalent if their
  truth tables reveal that the same input results
  in the same output
• ! ( A B) is equivalent to !A !B
• Where A and B are logical expressions

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HW

• From Book- p. 177 3.2, 3.3, 3.9, 3.10
• Explain your answers in detail. (Hint- Make some
  type of truth table)
• Due at beginning of next class

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Warm up

• 1. Consider writing a program to be used by a
  restaurant to keep track of the items on the
  menu, which include appetizers, main dishes and
  desserts. The restaurant wants to keep track,
  for every menu item, of the ingredients needed to
  prepare that item. Some operations will be
  implemented that apply to all menu itemsm and
  there will be some specialized

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Warm Up

• Consider the following two methods
• public static void printStuff(int x)
• int y1
• while (y
• System.out.print(y )
• y 2
• if (y x/2) return
• public static void mystery( )
• int x 8
• while (x 0)
• printStuff(x)
• x / 2
• System.out.println(x x)

• What will be the output when method mystery is
  called ?
• 1 2 1 1 1 x0
• 1 2 1 1 x0
• 1 2 2 x0
• 1 2 4 x8
• 1 2 x8

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Warm up picture
printStuff (int x) x y
Mystery x
OUTPUT
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Agenda

• Warm Up
• Collect HW
• Chapter 4 Review- Group Presentations
• Sections 4.0-4.5, 2.6, 2.0
• 30 minutes to prepare
• 5 minutes or less to present

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HW- you may start in class as needed

• P.240 true-false questions
• Provide justification for your answers
• Give counterexample if false
• Give explanation if true
• Read-Notes 248-255 (Start Chapter 5)

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Agenda

• Study Session
• Tracing the Code- Continued
• static modifier
• static variables
• static methods
• HW- p.293 5.1-5.9 T-F Give Explanations
• Notes- up to section 5.4

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Study Sessions
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Tracing the Code

• Where were we last time?
• Parameter Passing Example
• Pages 253-255

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Agenda 2-17-06

• Collect HW
• Programming Projects p.294 5.1
• Finish the Chapter
• interface
• Making one
• Using one

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Agenda 2-22-06

• Collect Missing Assignments
• Finishing the Chapter- Interfaces
• Programming Projects (Due by end of next class)
• P.294 5.2, 5.6, 5.7
• Test Chapter 4-5 (up to 5.4) Tuesday Feb 28th

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Time to Imagine

• Imagine a bunch of 4 year olds in the middle of
  a basketball court

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Time to Imagine

• And the adult in charge says OK, RUN!!!
• What will happen?

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Time to Imagine

• Now imagine the same set up with the following
  exception

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Time to Imagine

• A series of walls are put up. What will the kids
  do in this case?

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In Programming Chaos Should be avoided

• There needs to be some way for programmers to be
  organized and consistent
• One way this can be accomplished is through a
  well designed interface.

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interface - what is it?

• An interface looks like an empty class
• All methods are abstract and public
• Headers for methods are listed but not
  implemented
• An interface has no data members
• An interface may have constants
• public static final data

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More on interfaces

• To use an interface for a class you are creating,
  you use the keyword implements
• When a class implements a specific interface, it
  must create the details for each method that was
  listed in that interface.

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Example

• Suppose you wanted to write a Geometry program
  about shapes. Ultimately, your program will be
  able to create and measure properties of many
  shapes, such as circles, squares, trapezoids, and
  possible a shape you do not know about yet.
• Thinking abstractly what is something you would
  want to know about any shape in the program?

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Shapes interface

• You can design a Shape interface that would
  force anyone who introduces a new shape to write
  code in an organized way.
• public interface Shape
• public double getArea()
• public void printCenter()
• public void makeVisible()

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Shapes interface

• You can design a Shape interface that would
  force anyone who introduces a new shape to write
  code in an organized way.
• public interface Shape
• public double getArea()
• public void printCenter()
• public void makeVisible()

If I implement this interface, I will have to
make at least 3 methods
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AP Java Subset

• For the AP-A course, you need to be able to
  implement the Comparable interface
• It only has one method
• Int compareTo( Object obj)

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Agenda 2-24-06

• Finish 5.2 - 5.6 - 5.7 Be ready to show me by
  845
• Test Next Tuesday
• Similar format to the quizzes
• Multiple Choice
• Trace the code
• Write a method
• Notes- Power Point posted online

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Test Topics

• Chapter 4
• Chapter 5 up to 5.4
• Example of Parameter Passing
• Objects vs. Primitive types
• Example of implementing the Comparable interface