Question

A superclass Stock has been defined to store the details of the stock of a retail store. Define a subclass Purchase to store the details of the items purchased with the new rate and updates the stock. Some of the members of the classes are given below:

Class name: Stock 

Data members/instance variables: 

item: to store the name of the item 

qt: to store the quantity of an item in stock 

rate: to store the unit price of an item 

amt: to store the net value of the item in stock Member functions: 

Stock (…): parameterized constructor to assign values to the data members 

void display(): to display the stock details Class name: Purchase 

Data members/instance variables: 

pqty: to store the purchased quantity 

prate: to store the unit price of the purchased item 

Member functions/ methods:

Purchase(…): parameterized constructor to assign values to the data members of both classes 

void update (): to update stock by adding the previous quantity by the purchased quantity and replace the rate of the item if there is a difference in the purchase rate. Also, update the current stock value as (quantity * unit price) 

void display(): to display the stock details before and after updation. 

Specify the class Stock, giving details of 

the constructor() and void display(). Using the concept of inheritance, specify the class Purchase, giving details of the constructor(), void update() and void display(). 

The main function and algorithm need not be written.

Answer 1

class Stock 

{ 

String item; doubleqty,rate,amt; 

Stock(String a, double b, double c) 

{

item=a; 

qty=b; 

rate=c; 

amt=qty * rate; 

} 

void display() 

{ 

System.out.println("Name of the item: "+item); 

System.out.println("Quantity: "+qty); 

System.out.println("Rate per unit: "+rate); 

System.out.println("Net value: "+amt); 

} 

} 

class Purchase extends Stock 

{ 

int pqty; 

double prate; 

Purchase(String a, double b, double c, int d, double e) 

{ 

super(a, b, c);

 pqty=d;

 prate=e; 

} 

void update() { 

qty += pqty; 

if(prate!=rate) rate=prate; 

amt = qty * rate; 

} 

void display() 

{ 

super.display(); 

update(); 

super.display(); 

} 

}