Address book

Design a simple address book application using HashMap or TreeMap. Implement features such as adding contacts, searching by name, and deleting contacts.

Approach 1

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class Main {
    private Map<String, String> contacts;

    public Main() {
        contacts = new HashMap<>();
    }

    public void addContact(String name, String phoneNumber) {
        contacts.put(name, phoneNumber);
        System.out.println("Contact added: " + name + ", " + phoneNumber);
    }

    public void searchByName(String name) {
        String phoneNumber = contacts.get(name);
        if (phoneNumber != null) {
            System.out.println("Phone number for " + name + ": " + phoneNumber);
        } else {
            System.out.println("Contact not found: " + name);
        }
    }

    public void deleteContact(String name) {
        String phoneNumber = contacts.remove(name);
        if (phoneNumber != null) {
            System.out.println("Contact deleted: " + name);
        } else {
            System.out.println("Contact not found: " + name);
        }
    }

    public static void main(String[] args) {
        Main Main = new Main();
        Scanner scanner = new Scanner(System.in);
        while (true) {
            System.out.println("\nAddress Book Menu:");
            System.out.println("1. Add Contact");
            System.out.println("2. Search by Name");
            System.out.println("3. Delete Contact");
            System.out.println("4. Exit");
            System.out.print("Enter your choice: ");
            int choice = scanner.nextInt();
            scanner.nextLine(); // Consume newline
            switch (choice) {
                case 1:
                    System.out.print("Enter name: ");
                    String name = scanner.nextLine();
                    System.out.print("Enter phone number: ");
                    String phoneNumber = scanner.nextLine();
                    Main.addContact(name, phoneNumber);
                    break;
                case 2:
                    System.out.print("Enter name to search: ");
                    String searchName = scanner.nextLine();
                    Main.searchByName(searchName);
                    break;
                case 3:
                    System.out.print("Enter name to delete: ");
                    String deleteName = scanner.nextLine();
                    Main.deleteContact(deleteName);
                    break;
                case 4:
                    System.out.println("Exiting...");
                    System.exit(0);
                    break;
                default:
                    System.out.println("Invalid choice!");
            }
        }
    }
}

This program allows users to add contacts, search for contacts by name, and delete contacts. It uses a HashMap to store contacts, where the name is the key and the phone number is the value. The main method provides a simple text-based menu for users to interact with the address book.

Approach 2

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

class ContactDTO {
    private String name;
    private String phoneNumber;

    public ContactDTO(String name, String phoneNumber) {
        this.name = name;
        this.phoneNumber = phoneNumber;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPhoneNumber() {
        return phoneNumber;
    }

    public void setPhoneNumber(String phoneNumber) {
        this.phoneNumber = phoneNumber;
    }
}

public class AddressBook {
    private List<ContactDTO> contacts;

    public AddressBook() {
        contacts = new ArrayList<>();
    }

    public void addContact(String name, String phoneNumber) {
        ContactDTO contact = new ContactDTO(name, phoneNumber);
        contacts.add(contact);
        System.out.println("Contact added: " + name + ", " + phoneNumber);
    }

    public void searchByName(String name) {
        for (ContactDTO contact : contacts) {
            if (contact.getName().equalsIgnoreCase(name)) {
                System.out.println("Phone number for " + name + ": " + contact.getPhoneNumber());
                return;
            }
        }
        System.out.println("Contact not found: " + name);
    }

    public void deleteContact(String name) {
        ContactDTO foundContact = null;
        for (ContactDTO contact : contacts) {
            if (contact.getName().equalsIgnoreCase(name)) {
                foundContact = contact;
                break;
            }
        }
        if (foundContact != null) {
            contacts.remove(foundContact);
            System.out.println("Contact deleted: " + name);
        } else {
            System.out.println("Contact not found: " + name);
        }
    }

    public static void main(String[] args) {
        AddressBook addressBook = new AddressBook();
        Scanner scanner = new Scanner(System.in);
        while (true) {
            System.out.println("\nAddress Book Menu:");
            System.out.println("1. Add Contact");
            System.out.println("2. Search by Name");
            System.out.println("3. Delete Contact");
            System.out.println("4. Exit");
            System.out.print("Enter your choice: ");
            int choice = scanner.nextInt();
            scanner.nextLine(); // Consume newline
            switch (choice) {
                case 1:
                    System.out.print("Enter name: ");
                    String name = scanner.nextLine();
                    System.out.print("Enter phone number: ");
                    String phoneNumber = scanner.nextLine();
                    addressBook.addContact(name, phoneNumber);
                    break;
                case 2:
                    System.out.print("Enter name to search: ");
                    String searchName = scanner.nextLine();
                    addressBook.searchByName(searchName);
                    break;
                case 3:
                    System.out.print("Enter name to delete: ");
                    String deleteName = scanner.nextLine();
                    addressBook.deleteContact(deleteName);
                    break;
                case 4:
                    System.out.println("Exiting...");
                    System.exit(0);
                    break;
                default:
                    System.out.println("Invalid choice!");
            }
        }
    }
}

In this implementation:

• ContactDTO class represents the data transfer object for a contact, encapsulating the contact's name and phone number.

• AddressBook class manages the list of contacts and provides methods to add, search, and delete contacts.

• The main method provides a simple text-based menu for users to interact with the address book. Users can add contacts, search for contacts by name, and delete contacts.