POO Project 2025 - Tourism Application

Project Description

This application manages the database of museums and the organization of tourist groups. It is responsible for adding, searching, and managing guides, visitors, and museums efficiently.

Classes and exceptions:

Database, Museum, Person (Student and Professor extends Person), Location and Event are classes that were required. Aditionally, GroupNotExistsException, GroupThresholdException, GuideExistsException, GuideTypeException, PersonNotExistsException are exceptions that extend Exception class.

Design Patterns Used

For implementing this project, we have used the following design patterns:

1️⃣ Singleton - Database.java

Motivation:

• Prevents multiple instances of the database, ensuring a single source of truth for museums and tourist groups.
• Implementation:

  public class Database {
      private static Database instance;
      private Set<Museum> museums;
      private Set<Group> groups;
      
      private Database() {
          museums = new HashSet<>();
          groups = new HashSet<>();
      }
      
      public static Database getInstance() {
          if (instance == null) {
              instance = new Database();
          }
          return instance;
      }
  }

2️⃣ Builder - Location.java & Museum.java

Motivation:

• Enables the flexible and fluent construction of Location and Museum objects, ensuring readability and maintainability.
• Implementation:

  public class Location {
      private String county;
      private Integer sirutaCode;
      private String locality;
      private String adminUnit;
      private String address;
      private Integer latitude;
      private Integer longitude;
      
      private Location(Builder builder) {
          this.county = builder.county;
          this.sirutaCode = builder.sirutaCode;
          this.locality = builder.locality;
          this.adminUnit = builder.adminUnit;
          this.address = builder.address;
          this.latitude = builder.latitude;
          this.longitude = builder.longitude;
      }
      
      public static class Builder {
          private String county;
          private Integer sirutaCode;
          private String locality;
          private String adminUnit;
          private String address;
          private Integer latitude;
          private Integer longitude;
      
          public Builder(String county, Integer sirutaCode) {
              this.county = county;
              this.sirutaCode = sirutaCode;
          }
          
          public Builder setLocality(String locality) {
              this.locality = locality;
              return this;
          }
          
          public Builder setAdminUnit(String adminUnit) {
              this.adminUnit = adminUnit;
              return this;
          }
          
          public Location build() {
              return new Location(this);
          }
      }
  }

3️⃣ Factory Method - PersonFactory.java

Motivation:

• Centralizes the creation of Student and Professor objects, simplifying object instantiation and reducing code duplication.
• Implementation:

  public class PersonFactory {
      public static Person createPerson(String surname, String name, String role, int age, String email, String school, int studyYear, int experience) {
          if (role.equalsIgnoreCase("student")) {
              return new Student(surname, name, role, school, studyYear);
          } else if (role.equalsIgnoreCase("professor")) {
              return new Professor(surname, name, role, school, experience);
          }
          throw new IllegalArgumentException("Invalid role type");
      }
  }

4️⃣ Observer - Group.java

Motivation:

• Define a one-to-many dependency between objects so that all dependents are notified & updated when one object changes state.
• Ensures that guides are notified about events organized by museums.
• Implementation:

  public class Group implements Observer {
      private Professor guide;
      
      @Override
      public void update(String eventMessage) {
          if (guide != null) {
              System.out.println("To: " + guide.getEmail() + " ## Message: " + eventMessage);
          }
      }
  }

5️⃣ Command - CommandProcessor.java

Motivation:

• Encapsulate the request for a service.
• Allows the execution of commands without affecting the main structure of the program.
• Implementation:

  public interface Command {
      String execute(String[] parts, Database database);
  }

  public class AddMuseumCommand implements Command {
      @Override
      public String execute(String[] parts, Database database) {
          Museum museum = new Museum.Builder(parts[1], Long.parseLong(parts[2]), Long.parseLong(parts[3]), new Location.Builder(parts[4], Integer.parseInt(parts[5])).build()).build();
          database.addMuseum(museum);
          return "Museum added: " + parts[1];
      }
  }

Implemented Functionalities

• Add museums (ADD MUSEUM)
• Add tourist groups (ADD GROUP)
• Add guides and members (ADD GUIDE, ADD MEMBER)
• Search guides and members (FIND GUIDE, FIND MEMBER)
• Remove guides and members (REMOVE GUIDE, REMOVE MEMBER)
• Manage museum events (ADD EVENT)

Conclusion

This project follows OOP principles and implements 5 design patterns for a clear and extensible architecture.

Using Singleton, Builder, Factory Method, Observer, and Command ensures scalability and ease of maintenance.