UNIVERSITY OF WEST ATTICA
SCHOOL OF ENGINEERING
DEPARTMENT OF COMPUTER ENGINEERING AND INFORMATICS

University of West Attica · Department of Computer Engineering and Informatics

Software Development Methodologies

Vasileios Evangelos Athanasiou
Student ID: 19390005

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Supervision

Supervisor: Georgios Prezerakos, Professor

UNIWA Profile · LinkedIn

Co-supervisor: Angelos Georgoulas, Assistant Professor

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Athens, March 2023

This project implements Exercise 1: Classes and Objects, based on the specifications from the Department of Computer Engineering and Information Technology at the University of West Attica.

The goal is to design a Java class hierarchy that models different types of vehicles while practicing key Object-Oriented Programming (OOP) concepts.

The exercise demonstrates how to build a structured class hierarchy using:

• Inheritance
• Encapsulation
• Method overriding
• State management through class attributes

The system includes a base Vehicle class and two specialized classes:

• Car
• Plane

• Implement inheritance using a base Vehicle class and derived classes (Car, Plane)
• Manage class attributes and constructors
• Apply method overriding, especially the toString() method
• Handle state transitions, such as maintenance tracking based on usage

The Vehicle class contains attributes common to all vehicles.

• make
• model
• year
• weight
• needsMaintenance (boolean, default = false)
• tripsSinceMaintenance (int, default = 0)

repair()

public void repair() {
    tripsSinceMaintenance = 0;
    needsMaintenance = false;
}

Resets the maintenance state of the vehicle.

The Car class extends Vehicle.

• isDriving (boolean)
• horsepower (int)

• drive()
  • Sets isDriving = true
• stop()
  • Sets isDriving = false
  • Increments tripsSinceMaintenance

Maintenance rule:

If tripsSinceMaintenance > 100
→ needsMaintenance = true

The Plane class also extends Vehicle.

• isFlying (boolean)
• wingspan (float)

• fly()
  • Allowed only when needsMaintenance == false
  • Otherwise prints a warning message and prevents takeoff
• land()
  • Sets isFlying = false
  • Increments tripsSinceMaintenance

Maintenance rule:

If tripsSinceMaintenance > 80
→ needsMaintenance = true