Question

Given a class called Product,

Product
- id : String - price : double
+ Product() + Product(id : String, price : double) + getID() : String + getPrice() : double + toString() : String

Assume its toString method will return a string like this:

ID: id of this obj
Price: $xxx.xx

Write a FreshProduce class which extends Product. All instance data members should be private and all constructors and methods should be public unless specified otherwise. This FreshProduce class should:

• Have an instance data member expirationDate of String, which records the expiration date of such a product in a string;
• a default constructor (0 parameters);
• A constructor with three parameters to initialize all data members;
• Override the toString method to return a string including id, price, and expiration date. You must take advantage of the toString from the parent class.

Answer 1

class Product // base class
{
   private String id;
   private double price;
  
   //constructors
   public Product()
   {
       id = "";
       price = 0.0;
   }
   public Product(String id, double price)
   {
       this.id = id;
       this.price = price;
   }
   //get methods
   public String getID()
   {
       return id;
   }
   public double getPrice()
   {
       return price;
   }
   public String toString()
   {
       return "ID : "+getID() + String.format("\nprice :%.2f",getPrice());
   }
  
}

class FreshProduce extends Product // derived class
{
   private String expirationDate;
  
   public FreshProduce()
   {
       super();// call to base class constructor
       expirationDate = "";
   }
   public FreshProduce(String id, double price, String expirationDate)
   {
       super(id,price); // call to base class constructor
       this.expirationDate = expirationDate;
   }
   public String toString()
   {
       return super.toString() +"\nExpiration Date : "+expirationDate;
   }
}
class Test
{
   public static void main (String[] args)
   {
       FreshProduce tomato = new FreshProduce("A-123",10.55,"February 20, 2020");
      
       System.out.println(tomato);
   }
}

Output:

ID : A-123
price :10.55
Expiration Date : February 20, 2020

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