Question

Given the following program, finish the driver class to demonstrate polymorphism. Program: PolyMath Copy and paste your driver class into the textbox for grading.

I am having trouble understanding the concept of polymorphism. I know that I only need to edit the MathDriver.java (driver) class, but I am not entirely sure how.

Here is my MathDriver.java driver class, the one that I need to finish:

Here is the parent class, Math.java:

Lastly, here are the child classes, Addition, Subtraction, and Multiplication

Answer 1

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JAVA PORGRAM

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/////MathDriver.java

import java.util.Arrays;

public class MathDriver
{
   public static void main(String[] args) {
       int[] array = {5,6,3,4};
       //print the given array of integers
       System.out.println("Te given array is : "+Arrays.toString(array));
      
       //Create a Math array named mathOperations of size 3
       //The purpose of this array is to hold 3 child class instances of Math class
       //Since Math is a parent class so it can hold its child class instances
       Math mathOperations[] = new Math[3];
      
       //All the below classes is instantitated through parameterized constructor
       //by passing the array
      
       //Create instance of Addition class(child of Math) and store it @ 0th index
       mathOperations[0] = new Addition(array);
       //Create instance of Subtraction class(child of Math) and store it @ 1st index
       mathOperations[1] = new Subtraction(array);
       //Create instance of Multiplication class(child of Math) and store it @ 2nd index
       mathOperations[2] = new Multiplication(array);
      
      
       //Traverse through each Math object of mathOperations
       for(Math operation: mathOperations){
       //Since operation (Math reference) is basically holding child class instances
       //hence through runtime polymorphism , nNumbers methods defined (overridden) in the
       //respective child class will be called and accordingly result will be fetched
       int result = operation.nNumbers();
      
       //check operation is instance of which child class through instanceof
       //and print the result accordingly
       if(operation instanceof Addition)
       System.out.println("Result of Addition = "+result);
       else if(operation instanceof Subtraction)
       System.out.println("Result of Subtraction = "+result);
       else if(operation instanceof Multiplication)
       System.out.println("Result of Multiplication = "+result);
       }
      
   }
}

//////Math.java

//Parent class
public class Math{
protected int[] array;
protected int result;
  
Math(int[] array){
this.array = array;
result = 0;
}
  
public int nNumbers(){
result = 0;
  
for(int i =0; i < array.length; i++){
result = array[i];
}
  
return result;
}
}

/////////Addition.java

//Child class Addition
public class Addition extends Math{
  
Addition(int[] array){
super(array);
}
  
//overridden nNumbers method for Addition
public int nNumbers(){
result = 0;
  
for(int i =0; i < array.length; i++){
result += array[i];
}
  
return result;
}
  
public String toString(){
return ""+result;
}
}

//////////Subtraction.java

//Child class Subtraction
public class Subtraction extends Math{
Subtraction(int[] array){
super(array);
}
//overridden nNumbers method for Subtraction
public int nNumbers(){
result = array[0];
  
for(int i =1; i < array.length; i++){
result -= array[i];
}
  
return result;
}
  
public String toString(){
return ""+result;
}
}

////////////////Multiplication.java

//Child class Multiplication
public class Multiplication extends Math{
Multiplication(int[] array){
super(array);
}
  
//overridden nNumbers method for Multiplication
public int nNumbers(){
result = 1;
  
for(int i =0; i < array.length; i++){
result *= array[i];
}
  
return result;
}
  
public String toString(){
return ""+result;
}
}

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OUTPUT

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Te given array is : [5, 6, 3, 4]
Result of Addition = 18
Result of Subtraction = -8
Result of Multiplication = 360

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EXPLANATION

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Please check the inline commentns given in the MathDriver.java. It has detailed explanation of where and how the polymorphism is being used.