Custom Exception

This example simulates a banking system where you need to withdraw money from an account. The method checks if the account balance is sufficient for the withdrawal, and if not, it throws a custom exception.

// Step 1: Define a custom exception for insufficient funds
class InsufficientFundsException extends Exception {
    public InsufficientFundsException(String message) {
        super(message); // Pass the message to the superclass constructor
    }
}

class BankAccount {
    private double balance;

    // Constructor to initialize the balance
    public BankAccount(double initialBalance) {
        this.balance = initialBalance;
    }

    // Step 2: Method that throws the custom exception if funds are insufficient
    public void withdraw(double amount) throws InsufficientFundsException {
        if (amount > balance) {
            // Step 3: Throw the custom exception
            throw new InsufficientFundsException("Insufficient funds. Your balance is " + balance + ", but you tried to withdraw " + amount);
        }
        balance -= amount;
        System.out.println("Withdrawal successful! New balance: " + balance);
    }

    // Method to get the current balance
    public double getBalance() {
        return balance;
    }
}

public class ThrowsExample {
    public static void main(String[] args) {
        // Step 4: Create a BankAccount object with an initial balance
        BankAccount account = new BankAccount(100.00);

        try {
            // Attempt to withdraw more money than is available in the account
            account.withdraw(90.00);
        } catch (InsufficientFundsException e) {
            // Handle the exception if it occurs
            System.out.println("Exception caught: " + e.getMessage());
        }

        // Check the balance after the withdrawal attempt
        System.out.println("Final balance: " + account.getBalance());
    }
}