Calculating Fare prices

Previously, we learned Inheritance and Polymorphism by extending airline services, enabling code reusability and flexible behavior.

Welcome back,Developers!

Before starting this experiment, students should be familiar with:

• Relational Operators and Logical Operators

• Defining conditions using relational operators

• Conditional statements - if, if-else, nesting, switch-case

Imagine you are working in an airline company.

There are many flights:

• Some go within India → Domestic

• Some go outside India → International

All flights have:

• Flight Number

• Source

• Destination

• Base Fare

But ; Fare calculation is different for each type

So we say:

“Flight is a general idea — we don’t know how fare is calculated.”

That’s why:

Flight = Abstract Class

Add abstract keyword to flight class which you have created

Earlier, we were writing calculateFare() inside the same class:

Problem

• Fare calculation is different for each flight type

• But here we are forcing same logic for all flights

 This is wrong design

Solution

“We don’t know how fare is calculated for every flight.”

So we make it abstract

“Flight knows that fare must be calculated…but it doesn’t know HOW.”

“The parent defines WHAT to do, the child defines HOW to do.”

Override in Child Classes

 Domestic Flight

• Calculates fare with domestic charges

• Explains fare clearly to user

 International Flight

• Calculates fare with international charges

• Gives detailed breakdown

“Both flights are doing the same job — calculateFare()

but each one explains it in their own way.”

“We created flights… but where will we store them?”

• In array

• In memory

Suppose Airline company hires a manager to handle all flight records.”

This manager:

• Adds flights

• Shows flights

• Searches flights

• Deletes flights

“Company defines rules for manager — what work must be done.”

addFlight()

showAllFlights()

searchFlight()

deleteFlight()

“Interface defines WHAT to do, not HOW to do”

Define Rules (Interface)

Create interface

Add abstract methods:

Airline company tells manager:

 “You MUST do these 4 tasks… but how you do it is your choice.”

Now create FlightDAOImpl  class

Inherit to FlightDAO interface by using implements keyword

Override all methods

Create array and declare index variable which is initialized to zero

Add Logic for add Flight

Add Logic for show all flights

Add logic for search all flights

Add logic for delete flight

 Manager says:

“I will store flights in an array and manage them.”

Output :