PRACTICE QUESTIONS ON ABSTRACT CLASS – CLASS BANK

Create an abstract class “BankAccount” with abstract methods “deposit()” and “withdraw()”. Implement two subclasses “SavingsAccount” and “CheckingAccount” which extend “BankAccount” and implement the abstract methods. Create a “Customer” class which contains a customer of “BankAccount” objects. Add methods to the “Customer” class to display account balances, deposit/withdraw money, etc. Create objects of all classes and test their behavior. 

Solution :

abstract class BankAccount {
    protected double balance;

    public BankAccount(double balance) {
        this.balance = balance;
    }

    public abstract void deposit(double amount);
    public abstract void withdraw(double amount);
}

class SavingsAccount extends BankAccount {
    public SavingsAccount(double balance) {
        super(balance);
    }

    public void deposit(double amount) {
        balance += amount;
    }

    public void withdraw(double amount) {
        if (balance >= amount) {
            balance -= amount;
        } else {
            System.out.println("Insufficient funds");
        }
    }
}

class CheckingAccount extends BankAccount {
    public CheckingAccount(double balance) {
        super(balance);
    }

    public void deposit(double amount) {
        balance += amount;
    }

    public void withdraw(double amount) {
        double fee = 0.1 * amount;
        if (balance >= amount + fee) {
            balance -= amount + fee;
        } else {
            System.out.println("Insufficient funds");
        }
    }
}

class Customer {
    private BankAccount account;

    public Customer(BankAccount account) {
        this.account = account;
    }

    public void displayBalance() {
        System.out.println("Current balance: " + account.balance);
    }

    public void deposit(double amount) {
        account.deposit(amount);
    }

    public void withdraw(double amount) {
        account.withdraw(amount);
    }
}

public class AbstractExample {
    public static void main(String[] args) {
        BankAccount account = new CheckingAccount(1000.0);
        Customer customer = new Customer(account);

        customer.displayBalance();
        customer.deposit(500.0);
        customer.displayBalance();
        customer.withdraw(200.0);
        customer.displayBalance();
        customer.withdraw(1500.0); // Should print "Insufficient funds"
    }
}

Save the above Program with “AbstractExample .Java” then compile it with the following command :

javac AbstractExample.java //to compile the code 

java AbstractExample //to run the code

Output is :

Current balance: 1000.0
Current balance: 1500.0
Current balance: 1300.0
Insufficient funds