CS141: Topics for Week 9: Oct 19, 21, 23, 2015

Computer Science Headlines

ACM Tech News

Lab

Due Monday: Lab 6: Introduction to Graphical User Interfaces
Begin: Lab 7: More on Classes

Vocabulary: Chapter 6 A Second Look at Classes and Objects

• Object references
• Objects as method parameters and return types: Pass by Reference (not Pass by Value)
• The null keyword and Null Pointer Exceptions
• Self referencing using the keyword this
• Overloading: Methods with the same name but a different list of parameter types
• Class (static) methods and variables - class methods can only access class variables
  • Instance Variables
  • Class vs Instance Variables
  • Class vs Instance Methods
  • Only one copy exists of a static field regardless of how many objects that that type exist.
  • Don't need to create an object in order to access static fields, e.g. see Math class.
• Writing your own .equals method. Need to do this if you want to compare objects which contains instances of other objects (aggregation). Also consider the compareTo() method and the Comparable interface.
• Deep copying - don't create a copy using references of the member variables.
  Also, when returning a member variable, it can be safer to return a copy and not the reference.
• Enumeration Type Example
• See list of common errors on p. 435 of your text.

In Class Practice Activities

• Practice creating copy constructors using the Game Program. Also generate the Javadoc for it!
• Working with Object References: See Exam 2, problem 3 from 2013.
• Pass by Value vs Pass by Reference (pdf)
• Create the Dog class above.

---