CS141: Topics for Oct 28, 30, & Nov 1, 2013

Homework and Reading

The reading and homework for this week can be found here: Lab 10

new programming assignment??

Chp 8 Vocabulary

Object-oriented programming Encapsulation Public interface Private implementation Class Object (instance of class) Member (instance) variable Instance method Constructor The keyword: new Object reference Null reference

Mutator method (setter) Accessor method (getter) toString method Sending a message Overloading Class (static) method Class (static) variables Modifier (public, private) this reference Unit testing

Topics: Chp 8 - Objects and Classes

• Motivation of Classes and Objects: Organizing and structuring code to promote reusability, readability, and correctness
• Encapsulation: Separating the public interface from the private (hidden) implementation
• Class vs Object Analogies: script vs actor, cookie recipe vs the cookie itself
• Examples: Die class, Card class
• Components of a Class (also see categories):
  • Data:
    • Member (instance) variables (one for each object)
    • Class (static) variables (one for all objects)
  • Actions:
    • Public interface (public methods)
      • Common for most classes:
        • Access to data: Mutators and Accessors (also called getters and setters)
        • Handy Utilities: toString
        • Creation: Constructor
      • Public methods for a specific class (e.g. In the Die class, one might have a roll() method)
    • Private Implementation:
      • Data hiding: data is usually private. Use accessors & mutators instead.
      • private methods - not accesible from outside of the class.
• Working with Objects
  • Creating an object using the keyword new and a constructor
  • Object references
  • Objects as method parameters and return types: Pass by Reference (not Pass by Value)
    *** Recall discussion with arrays
  • The null keyword and Null Pointer Exceptions
  • Testing your code.
  • Sending an object a message using the public interface. (calling a method)
  • Self referencing using the keyword this
• Overloading: Methods with he same name but different signatures (headers)
• Class (static) methods and variables - class methods can only access class variables

In Class Practice Activities

• Basic Class & Object Problems (pdf) (creating a Die class and objects)
• The execution of program. Create the Object diagrams given the rough Class Diagram

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