Basic HTML version of Foils prepared Sept 6 1998

Foil 33 Abstract Methods and Classes

From Java Tutorial 98-2: Java Language and Object Oriented Techniques CPS606 Fall Semester 1999 -- Sept 7 1999. by Geoffrey C. Fox, Nancy McCracken
An abstract method has no body - it is provided in a class to define the signature of the method for program structuring purposes. It must be defined in some subclass of the class in which it is declared.
  • Constructors, static methods, private methods cannot be abstract
  • A method that overrides a superclass method cannot be abstract
Classes that contain abstract methods and classes that inherit abstract methods without overriding them are considered abstract classes
  • It is compile-time error to instantiate an abstract class or attempt to call an abstract method directly.

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