CS 141 Topics

CS141: Topics for Week 4: Sept 14, 16 & 18, 2015

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Lab

Lab 3: Classes and Objects (cont)
Remember to review questions starting on p. 183.

Chapter 3 Vocabulary - Continued from Week 3

Object-oriented programming & Class Structure
  ... Class (user defined type)
  ... Object (instance of class)
  ... primitive type vs class type
  ... Attributes, Fields, or Member variables (data)
  ... Methods (actions)

Method Structure:
  ... access specifier or modifier (e.g. public, private)
  ... method name
  ... method parameters
  ... return type, return value
  ... variable scope: local vs global, shadowing

Class Structure (more detail):
  ... Constructors, default constructor
  ... Public interface
  ... Private implementation, data hiding
  ... Mutator methods (setter)
  ... Accessor methods (getter)
  ... toString method
Object Creation and Use
  ... The keyword: new
  ... Sending a message, calling a method
  ... dot notation
  ... (formal) parameter vs argument (actual parameter)
  ... parameter passing
  ... Null pointer and the Null Pointer Exceptions

Code Design and Development
  ... UML Diagram
  ... API (Application Programmer Interface)
  ... Encapsulation, modularization
  ... stepwise refinement
  ... reusability

Testing and Debugging
  ... debugging & testing
  ... tracing code

Topics (cont):

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

Example: Die class (note this is done in chap 4! p. 264 using the Random class, not Math.random

Components of a Class (also see class template):
- Data (Attributes, Fields):
  - Member (instance) variables (one for each object)
  - Class (static) variables (one for all objects)
- Actions:
  - Public interface (public methods)
    - Common for most classes:
      - Creation: Constructor
      - Access to data: Mutators and Accessors (also called getters and setters)
      - Handy Utility: toString
    - 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
- 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
See list of common errors on p. 183 of your text.

CS141: Topics for Week 4: Sept 14, 16 & 18, 2015

Computer Science Headlines

Lab

Chapter 3 Vocabulary - Continued from Week 3

Topics (cont):

In Class Practice Activities