Basic HTML version of Foils prepared Sept 6 1998

Foil 22 Java Language -- Types of Classes - II

From Java Tutorial 98-2: Java Language and Object Oriented Techniques CPS606 Fall Semester 1999 -- Sept 7 1999. by Geoffrey C. Fox, Nancy McCracken
threadsafe: Instance or static variables will never change asynchronously and so can use compiler optimizations such as assigning to registers. Next modifier -- final -- is also valuable to compilers
final -- Cannot have a subclass for classes
  • cannot be overridden for methods
  • final variables have a constant value e.g.
    • final int ageatdeath = 101;
  • transient -- specifies that objects are not persistent
  • Note most of these modifiers can be used either for a class or an object -- a particular instance of a class
    • abstract only makes sense for a class and transient is perhaps more useful on an object basis

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