CS141: Topics for Week 10: Mar 19/21/23, 2018

Computer Science Headlines: ACM Tech News

Reading:

• Chp 8: Designing Classes

Lab and Other Activities

• Lab 8: Class/Static Variables

Lecture Discussion Topics:

• Review File I/O from last week. Also, for reading mulitple items on a single line in a data file, use the split() method in the String class:

  Scanner reader = new Scanner(file);
  while (reader.hasNext()) {
  	String line = reader.nextLine();
  	String[] tokens = line.split(" ");  // delimiter is a space 
  	String name = tokens[0].trim();
  	int val = Integer.parseInt(tokens[1].trim());
  	...
  }

• 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.
• Write a .equals method for the Card class. Need to do this if you want to compare objects. Also write a compareTo() method and using 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.
• More on GUI interfaces - scroll bar and text area.
• Enumeration Type Example

Concepts and Vocabulary

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