Final Projects and Real-World Applications

import java.util.*;

class BankAccount {
    private String accountNumber;
    private String holderName;
    private double balance;
    private List<String> transactions = new ArrayList<>();

    public BankAccount(String accountNumber, String holderName, double initialDeposit) {
        this.accountNumber = accountNumber;
        this.holderName = holderName;
        this.balance = initialDeposit;
        transactions.add("Account created with $" + initialDeposit);
    }

    public void deposit(double amount) {
        if (amount > 0) {
            balance += amount;
            transactions.add("Deposited: $" + amount);
            System.out.println("Deposited $" + amount + ". New balance: $" + balance);
        }
    }

    public void withdraw(double amount) {
        if (amount > 0 && amount <= balance) {
            balance -= amount;
            transactions.add("Withdrew: $" + amount);
            System.out.println("Withdrew $" + amount + ". New balance: $" + balance);
        } else {
            System.out.println("Insufficient funds!");
        }
    }

    public void printStatement() {
        System.out.println("\n=== BANK STATEMENT ===");
        System.out.println("Account: " + accountNumber);
        System.out.println("Holder: " + holderName);
        transactions.forEach(t -> System.out.println("  • " + t));
        System.out.printf("Current Balance: $%.2f%n", balance);
        System.out.println("======================");
    }

    public String getAccountNumber() { return accountNumber; }
    public double getBalance() { return balance; }
}

public class BankingSystem {
    static Map<String, BankAccount> accounts = new HashMap<>();
    static Scanner sc = new Scanner(System.in);

    public static void main(String[] args) {
        boolean running = true;
        while (running) {
            System.out.println("\n=== BANKING SYSTEM ===");
            System.out.println("1. Create Account  2. Deposit  3. Withdraw  4. Statement  5. Exit");
            System.out.print("Choice: ");
            int choice = sc.nextInt(); sc.nextLine();

            switch (choice) {
                case 1: createAccount(); break;
                case 2: deposit(); break;
                case 3: withdraw(); break;
                case 4: statement(); break;
                case 5: running = false; System.out.println("Goodbye!"); break;
            }
        }
    }

    static void createAccount() {
        System.out.print("Name: "); String name = sc.nextLine();
        System.out.print("Initial deposit: $"); double deposit = sc.nextDouble();
        String accNum = "ACC" + (1000 + accounts.size());
        accounts.put(accNum, new BankAccount(accNum, name, deposit));
        System.out.println("Account created! Number: " + accNum);
    }

    static void deposit() {
        System.out.print("Account number: "); String acc = sc.nextLine();
        BankAccount account = accounts.get(acc);
        if (account != null) {
            System.out.print("Amount: $"); double amount = sc.nextDouble();
            account.deposit(amount);
        } else System.out.println("Account not found.");
    }

    static void withdraw() {
        System.out.print("Account number: "); String acc = sc.nextLine();
        BankAccount account = accounts.get(acc);
        if (account != null) {
            System.out.print("Amount: $"); double amount = sc.nextDouble();
            account.withdraw(amount);
        } else System.out.println("Account not found.");
    }

    static void statement() {
        System.out.print("Account number: "); String acc = sc.nextLine();
        BankAccount account = accounts.get(acc);
        if (account != null) account.printStatement();
        else System.out.println("Account not found.");
    }
}

import java.util.*;

class Book {
    String isbn, title, author;
    boolean isAvailable;

    Book(String isbn, String title, String author) {
        this.isbn = isbn; this.title = title; this.author = author;
        this.isAvailable = true;
    }

    @Override
    public String toString() {
        return String.format("[%s] %s by %s - %s",
            isbn, title, author, isAvailable ? "Available" : "Checked Out");
    }
}

public class LibrarySystem {
    static List<Book> library = new ArrayList<>();
    static Scanner sc = new Scanner(System.in);

    public static void main(String[] args) {
        // Seed some books
        library.add(new Book("001", "Clean Code", "Robert C. Martin"));
        library.add(new Book("002", "Effective Java", "Joshua Bloch"));
        library.add(new Book("003", "Design Patterns", "Gang of Four"));

        boolean running = true;
        while (running) {
            System.out.println("\n=== LIBRARY MANAGEMENT ===");
            System.out.println("1. List Books  2. Search  3. Checkout  4. Return  5. Add Book  6. Exit");
            System.out.print("Choice: ");
            int choice = sc.nextInt(); sc.nextLine();

            switch (choice) {
                case 1: library.forEach(System.out::println); break;
                case 2:
                    System.out.print("Search: "); String query = sc.nextLine().toLowerCase();
                    library.stream()
                        .filter(b -> b.title.toLowerCase().contains(query) ||
                                     b.author.toLowerCase().contains(query))
                        .forEach(System.out::println);
                    break;
                case 3:
                    System.out.print("ISBN: "); String isbn = sc.nextLine();
                    library.stream().filter(b -> b.isbn.equals(isbn) && b.isAvailable)
                        .findFirst().ifPresentOrElse(
                            b -> { b.isAvailable = false; System.out.println("Checked out: " + b.title); },
                            () -> System.out.println("Not available."));
                    break;
                case 4:
                    System.out.print("ISBN: "); String retIsbn = sc.nextLine();
                    library.stream().filter(b -> b.isbn.equals(retIsbn) && !b.isAvailable)
                        .findFirst().ifPresentOrElse(
                            b -> { b.isAvailable = true; System.out.println("Returned: " + b.title); },
                            () -> System.out.println("Book not found or already returned."));
                    break;
                case 5:
                    System.out.print("ISBN: "); String newIsbn = sc.nextLine();
                    System.out.print("Title: "); String title = sc.nextLine();
                    System.out.print("Author: "); String author = sc.nextLine();
                    library.add(new Book(newIsbn, title, author));
                    System.out.println("Book added!");
                    break;
                case 6: running = false; break;
            }
        }
    }
}

import java.util.*;

class Question {
    String question;
    String[] options;
    int correctAnswer;

    Question(String question, String[] options, int correctAnswer) {
        this.question = question;
        this.options = options;
        this.correctAnswer = correctAnswer;
    }
}

public class QuizApp {
    public static void main(String[] args) {
        List<Question> questions = List.of(
            new Question("What is the size of int in Java?",
                new String[]{"2 bytes", "4 bytes", "8 bytes", "1 byte"}, 2),
            new Question("Which keyword creates an object?",
                new String[]{"create", "new", "make", "object"}, 2),
            new Question("String is which type?",
                new String[]{"Primitive", "Non-Primitive", "Static", "Final"}, 2),
            new Question("JVM stands for?",
                new String[]{"Java Variable Machine", "Java Virtual Machine",
                             "Java Version Manager", "Java Visual Mode"}, 2),
            new Question("Which collection allows no duplicates?",
                new String[]{"ArrayList", "LinkedList", "HashSet", "HashMap"}, 3)
        );

        Scanner sc = new Scanner(System.in);
        int score = 0;

        System.out.println("=== JAVA QUIZ ===\n");
        for (int i = 0; i < questions.size(); i++) {
            Question q = questions.get(i);
            System.out.println("Q" + (i + 1) + ": " + q.question);
            for (int j = 0; j < q.options.length; j++) {
                System.out.println("  " + (j + 1) + ". " + q.options[j]);
            }
            System.out.print("Your answer (1-4): ");
            int answer = sc.nextInt();
            if (answer == q.correctAnswer) {
                System.out.println("✅ Correct!\n");
                score++;
            } else {
                System.out.println("❌ Wrong! Correct: " + q.options[q.correctAnswer - 1] + "\n");
            }
        }

        System.out.printf("=== RESULT: %d/%d (%.0f%%) ===%n",
            score, questions.size(), (double) score / questions.size() * 100);

        if (score == questions.size()) System.out.println("🏆 Perfect Score!");
        else if (score >= questions.size() * 0.7) System.out.println("👍 Great job!");
        else System.out.println("📚 Keep studying!");

        sc.close();
    }
}