CS180 Final Exam Review

1
CS180 Final Exam Review

• December 8th, 2006

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Final Exam Information At A Glance

• Date
• Tuesday, December 12th, 2006
• Place
• EE129
• Time
• 1020am 1220pm
• Cumulative
• Worth 20 of your final grade

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Important Topics

• Object-Oriented Design (Chapter 1)
• Primitives
• Objects, Classes, and Strings (Chapters 4 and 7)
• Selection Statements (Chapter 5)
• Repetition Statements (Chapter 6)
• Exception and Assertions (Chapter 8)
• Arrays (Chapter 10)
• File I/O (Chapter 12)
• Inheritance and Polymorphism (Chapter 13)
• Generics (Supplemental Chapter)
• Recursion (Chapter 15)
• GUI and Event-Driven Programming (Chapter 14)

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Object-Oriented Design

• Methods
• Extract small parts of a program and calculations
  which will be performed multiple times
• Encapsulation
• Classes, Objects, and Polymorphism
• Covered in more detail later

5
Primitives

• int, double, boolean, float, char, etc.
• These are NOT Objects
• Can be compared with , !, lt, gt, etc.
• Cannot call methods
• There is an Integer class, Character class, etc.
  which is different from a primitive
• Explicit type-casting may need to be done
• byte?short?int?long?float?double

6
Objects and Classes and Strings (oh my!)

• Objects are handled with a reference address
• Two objects can be compared with the .equals()
  method
• Do NOT use to compare objects
• Assignment operators assign references they do
  not make separate copies
• Beware of NullPointerExceptions
• Constructors should be used to initialize class
  variables
• Methods in a class can only be called on an
  object of that class (or an object of a
  descendent of that class)
• Keyword this

7
Objects and Classes and Strings (oh my!)

• Strings are a type of object
• Also cannot be compared with
• Can be concatenated with the operator
• Important String functions
• charAt
• indexOf
• substring
• length

8
Selection Statements

• Modifies the flow of control of the program
• if/else construct
• Must have a boolean condition to check against
• are important, but not necessary for one line
  statements
• else branch is optional
• switch construct
• Multi-way branch which makes a decision based on
  a char, byte, short, or int
• default case
• break statement

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Repetition Statements

• for
• while
• do-while
• Pitfalls
• Off-by-one errors
• Infinite looping
• Overflow

10
Exceptions and Assertions

• Use a try/catch/finally block to handle
  exceptions thrown by a program
• Use throw statement to notify program of an error
• Do not need to catch RunTimeExceptions
• These should be checked for instead
• User defined exceptions must extend Exception
• Assert
• Used for correctness

11
Arrays

• Linear collection of data
• Can hold primitives or Objects, but must all be
  of the same type
• length tells the number of elements in the array
• Member, not a method
• Indexed from 0 to length 1
• Protect against ArrayIndexOutOfBoundsException
• Can create multiple dimension arrays
• Usually use for-loops to iterate through members
  of the array

12
File I/O

• Many classes
• FileInputStream, DataInputStream, FileReader,
  BufferedReader, Scanner, PrintWriter,
  DataOutputStream, etc.
• ObjectInputStream, ObjectOutputStream
• Used to write objects to a file
• Any object serialized by a stream must implement
  Serializable
• Which classes are used to write text and which
  are used to write binary?
• Always close files you open

13
Inheritance and Polymorphism

• Differences between abstract classes and
  interfaces
• Polymorphism can simplify code
• Extend specific classes from general classes
• Use protected keyword to protect information and
  methods
• No need to rewrite methods which are the same as
  in a parent class
• Superconstructor is always called as the first
  line of constructor

14
Generics

• Commonly used for collections of objects
• Can use bounded type to further restrict the type
  of object allowed
• All Collections in Java use generics
• Type safety can no longer put two completely
  different types of objects in the same collection

15
Recursion

• Think about what the sub-problem is
• Only be concerned with the current level of
  recursion
• Two necessary cases
• Base case
• Recursive case

16
GUI and Event-driven Programming

• Common classes
• JFrame
• JPanel
• JLabel
• JMenu, JMenuItem
• JButton
• You will not be asked to code a substantial GUI

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Disclaimer

• These slides are simply a review of the course
  material and are not meant to cover everything
  you may be responsible for knowing for the final
  exam
• Complete sets of slides for both lectures and
  recitations can be found on the course webpage