Multi level hierarchy

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Multi level hierarchy


Objectives

On completion of this period, you would be able to know

• Multi level inheritance hierarchy

• To create multi level inheritance hierarchy


Recap

Super key word • When ever a subclass needs to refer to it’s

immediate upper class it can do so by using super keyword


Multi Level Inheritance Hierarchy

One can build hierarchies that contain as many layers of inheritances as one like

Given three classes A,B,C C can be sub class of B, which is a sub class of A

A : super class to B

B : sub class of A, super class of C

C : subclass of B and A

A

B

C

Fig. 24.1. Multi level hierarchy


• With the above description each subclass inherits all the properties found in all of its super class

• In the above diagram case

C inherits all aspects of B and A

Multi Level Inheritance Hierarchy contd..


A derived class with multilevel base classes is declared as follows class A{ -------- --------}class B extends A // first level { ------ ------} class C extends B // second level { ------- ---------}

Multi Level Inheritance Hierarchy contd..


Discussion

• Can you give any real life example for multi level inheritance hierarchy

• Employee – Manager – Clerk – WagedEmployee• Manager – AccountsDepartment• Manager – IT Department• Manger - HRD

Employee

Manger Clerk WagedEmployee

Accounts Department IT Department HRD

Fig. 24.2. Real life example fro multi level hierarchy


Discussion contd..

• Can you give any software example for multi level inheritance hierarchy

• Shape – Rectangle – Circle – Triangle• Rectangle – Square - RoundedRectangle

Shape

Rectangle Circle Traingle

Square RoundedRectangle

Fig. 24.3. Software example fro multi level hierarchy


• Consider the following example

• Add a class Shipment to the class BoxWeight which is a sub

class of Box

Program To Create Multi Level Hierarchy

Box

BoxWeight

Shipment

Fig. 24.4. Example on Multi level Hierarchy

Box : Super class

BoxWeight : Subclass to Box class

super to shipment

Shipment : Newly added sub class to BoxWeight


class Box{ private double width; private double height; private double depth;// construct clone of one objectBox(Box ob) { // pass object to constructor width = ob.width; height = ob.height; depth = ob.depth; }

Program To Create Multi Level Hierarchy contd..


//Constructor used when all dimensions specified

Box(double w, double h, double d) {

width = w;

height = h;

depth = d;

}

// constructor used when no dimensions specified

Box(){



// constructor used when no dimensions specifiedBox(){

width = -1; // use -1 to indicate an uninitialized box

height = -1;

depth = -1;

}

// constructor used when a cube is created

Box(double len){

width = height = depth = len;

}



// Compute and return volume double volume() { return width * height * depth;

}}// BoxWeight now fully implements all constructors. class BoxWeight extends Box { double weight; // weight box// construct clone of an objectBoxWeight( BoxWeight ob) { // pass object to constructor



super(ob); weight = ob.weight; }// constructor when all parameters are apecifiedBoxWeight ( double w, double h, double d, double m) {

super(w,h,d); //call super class constructor weight = m;}

// default constructor BoxWeight() {Super(); weight = -1;}



// constructor used when cube is created

BoxWeight( double len, double m) {

super(len); weight = m; }}



// Add shipping costs class Shipment extends BoxWeight { double cost;// construct clone of an object. Shipment(Shipment ob) { // pass object to constructor super(ob); cost = ob.cost;}



// constructor when all parameters are specifiedShipment(double w, double h, double d, double m, double c) {super( w,h,d,m); //call superclass constructor cost = c; }//default constructorShipment() { super(); cost = -1; }//constructor used when cube is createdShipment( double len, double m, double c) { super(len,m);} }



class DemoShipment {

public static void main( String args[]) {

double vol;

Shipment shipment1 = new Shipment(10,20,15,10,3.41);

Shipment shipment2 = new Shipment(2,3,4,0.76,1.28);

vol = shipment1.volume();

System.out.println( “Volume of shipment1 is ” + vol);

System.out.println( “weight of shipment1 is” +

shipment1.weight);

System.out.println( “shipping cost : $” +shipment1.cost);

System.out.println();



vol = shipment2.volume();System.out.println( “Volume of shipment2 is ” + vol);System.out.println( “weight of shipment2 is”

+ shipment2.weight);System.out.println( “shipping cost : $” +shipment2.cost);System.out.println();}

}



Output of program

Volume of shipment1 is 3000.0Weight of shipment1 is 10.0Shipping cost : $3.41

Volume of shipment2 is 24.0Weight of shipment2 is 0.76Shipping cost : $1.28


Summary

• In this class we have discussed• Multi level hierarchy• Creating multi level hierarchy


1.

The above figure depicts

a) Single Inheritance

b) Hierarchical inheritance

c) Multilevel inheritance

A

B

C

Quiz


Frequently Asked Questions

1. What is multi level hierarchy ?

2. Explain how to create a multilevel hierarchy with an example program

Multi level hierarchy

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