Hide Notes 

Slide 1: Inheritance http://ecomputernotes.com
Slide 2: Recap – Inheritance class inherits all the characteristics of the base class ►Derived inherited characteristics, derived class may have its own unique characteristics ►Besides ►Major benefit of inheritance is reuse http://ecomputernotes.com
Slide 3: Concepts Related with Inheritance ►Generalization ►Subtyping (extension) (restriction) ►Specialization http://ecomputernotes.com
Slide 4: Generalization OO models, some classes may have common characteristics ►In extract these features into a new class and inherit original classes from this new class ►We ►This concept is known as Generalization http://ecomputernotes.com
Slide 5: Example – Generalization Line color vertices length move setColor getLength color vertices radius move setColor computeArea Circle Triangle color vertices angle move setColor computeArea http://ecomputernotes.com
Slide 6: Example – Generalization Shape color vertices move setColor Circle radius computeArea Triangle Line length getLength http://ecomputernotes.com angle computeArea
Slide 7: Example – Generalization Student name age gender program studyYear study heldExam eat walk Teacher name age gender designation salary teach takeExam eat walk http://ecomputernotes.com Doctor name age gender designation salary checkUp prescribe eat walk
Slide 8: Example – Generalization name age gender eat walk Person Student program studyYear study heldExam Teacher designation salary teach takeExam Doctor designation salary checkUp prescribe
Slide 9: Sub-typing & Specialization want to add a new class to an existing model ►We an existing class that already implements some of the desired state and behaviour ►Find the new class from this class and add unique behaviour to the new class ►Inherit http://ecomputernotes.com
Slide 10: Sub-typing (Extension) ►Sub-typing means that derived class is behaviourally compatible with the base class compatible means that base class can be replaced by the derived class ►Behaviourally http://ecomputernotes.com
Slide 11: Person name age gender eats walks Example – Sub-typing (Extension) Student program studyYear study takeExam
Slide 12: Shape color vertices setColor move Example – Sub-typing (Extension) Circle radius computeCF computeArea
Slide 13: Specialization (Restriction) ►Specialization means that derived class is behaviourally incompatible with the base class incompatible means that base class can’t always be replaced by the derived class ►Behaviourally http://ecomputernotes.com
Slide 14: Example – Specialization (Restriction) Person age : [0..100] … setAge( a ) … age = a Adult age : [18..100] … setAge( a ) … If age < 18 then error else age = a
Slide 15: Example – Specialization (Restriction) IntegerSet … add( elem ) … add element to the set NaturalSet … add( elem ) … If elem < 1 then error else add element to the set
Slide 16: Overriding class may need to override the default behaviour provided by its base class ►A ►Reasons for overriding Provide behaviour specific to a derived class Extend the default behaviour Restrict the default behaviour Improve performance http://ecomputernotes.com
Slide 17: Example – Specific Behaviour Shape color vertices draw move setColor Circle radius draw computeArea Triangle Line length draw angle draw computeArea
Slide 18: Example – Extension Window width height open close draw DialogBox controls enable draw 1- Invoke Window’s draw 2- draw the dialog box
Slide 19: Example – Restriction IntegerSet … add( elem ) … Add element to the set NaturalSet … add( elem ) … If elem < 1 then give error else Add element to the set http://ecomputernotes.com
Slide 20: Example – Improve Performance Shape ► Class Circle overrides rotate operation of class Shape with a Null operation. color coord draw rotate setColor Circle radius draw rotate
Slide 21: Abstract Classes abstract class implements an abstract concept ►Main purpose is to be inherited by other classes ►Can’t be instantiated ►Promotes reuse ►An http://ecomputernotes.com
Slide 22: Example – Abstract Classes Person name age gender eat walk Student ►Here, Teacher Doctor Person is an abstract class
Slide 23: Example – Abstract Classes Vehicle color model accelerate applyBrakes Car Truck Bus ►Here, Vehicle is an abstract class
Slide 24: Concrete Classes ►A concrete class implements a concrete concept purpose is to be instantiated ►Main implementation details specific to the domain context ►Provides http://ecomputernotes.com
Slide 25: Example – Concrete Classes Person Student program studyYear study heldExam Teacher Doctor Student, Teacher and Doctor are concrete classes ►Here,
Slide 26: Example – Concrete Classes Vehicle Car Truck capacity load unload Bus • Here, Car, Bus and Truck are concrete classes