ITEC 120: Week 4

• Lab 7

• Lab 6

• Comments on quizzes
1. Constant needed
2. Constant style
3. Meaningful names
4. Indentation
5. Comment style
6. Stay ahead of the wave!
• Selected Topics from Chapter 3:
• Classes are (user defined) types
• Good style: class names are capitalized
• object.method() invokes a method
• Good style: method names not capitalized
• Methods do one of the following:
1. perform services (eg System.out.println();
2. return values to use in expressions and assignments (scan.nextInt();
• Aliases
• Assignment of reference variables copies pointer
• Can have two references to same object
• An alias
of a reference is another reference with a different name (eg two variables with same pointer value)
• Be careful with references: changes made via one alias are reflected for all aliases
• Garbage:
  • an object with no references to it
  • garbage is no longer accessible)
• Garbage collection
• Return garbage to runtime system for reuse
• automatic in java
• not automatic in C, C++, Ada, FORTRAN, COBOL
• automatic in some OO languages: Eiffel, smalltalk
• automatic in scripting languages like perl, php, vb(?)
• automatic in AI languages like LISP, PROLOG
• String class
• Special notation for creating Strings
• Strings are immutable
• Strings methods
• String characters indexed (starting at 0)
• Packages
• Libraries: tools for programmer
• Packages: organization tool for libraries
• organization tool for libraries
• package hierarchy: use dot notation (eg java.util.Scanner)
• Style: not capitalized
• Import: saves programmer typing
• packages random and class


• Method Declarations: parameters and return types


• Formatting Output


• Random Numbers




• Chapter 3 Powerpoint Slides


• Examples from Chapter 3