ITEC 120: Week 4
- Lab 7
- Lab 6
- Comments on quizzes
- Constant needed
- Constant style
- Meaningful names
- Indentation
- Comment style
- 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:
- perform services (eg System.out.println();
- 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