Question

Modify the BankAccount class to throw IllegalArgumentException exceptions, create your own three exceptions types. when the account is constructed with negative balance, when a negative amount is deposited, or when an amount that is not between 0 and the current balance is withdrawn. Write a test program that cause all three exceptions occurs and catches them all.

/**
A bank account has a balance that can be changed by
deposits and withdrawals.
*/
public class BankAccount
{
private double balance;

/**
Constructs a bank account with a zero balance
*/
public BankAccount()
{   
balance = 0;
}

/**
Constructs a bank account with a given balance
@param initialBalance the initial balance
*/
public BankAccount(double initialBalance)
{   
if (initialBalance < 0)
throw new NegativeBalanceException(
"Cannot create account: " + initialBalance + " is less than zero");   
  
balance = initialBalance;
}

/**
Deposits money into the bank account.
@param amount the amount to deposit
*/
public void deposit(double amount)
{
if (amount < 0)
throw new NegativeAmountException(
"Deposit of " + amount + " is less than zero");
double newBalance = balance + amount;
balance = newBalance;
}

/**
Withdraws money from the bank account.
@param amount the amount to withdraw
*/
public void withdraw(double amount)
{   
if (amount < 0)
throw new NegativeAmountException(
"Withdrawal of " + amount + " is less than zero");
  
if (amount > balance)
throw new InsufficientFundsException(
"Withdrawal of " + amount + " exceeds balance of " + balance);
  
double newBalance = balance - amount;
balance = newBalance;
}

/**
Gets the current balance of the bank account.
@return the current balance
*/
public double getBalance()
{   
return balance;
}
}
---------------

/**
A class to test the BankAccount class.
*/
public class BankAccountTester2
{
public static void main(String[] args)
{
BankAccount harrysChecking = new BankAccount();
  
try
{
harrysChecking.deposit(300);
System.out.println("success");
}
catch (IllegalArgumentException e)
{
System.out.println("exception");
}
System.out.println("Expected: success");

try
{
harrysChecking.withdraw(100);
System.out.println("success");
}
catch (IllegalArgumentException e)
{
System.out.println("exception");
}
System.out.println("Expected: success");

try
{
harrysChecking.deposit(-100);
System.out.println("success");
}
catch (IllegalArgumentException e)
{
System.out.println("exception");
}
System.out.println("Expected: exception");

try
{
harrysChecking.withdraw(300);
System.out.println("success");
}
catch (IllegalArgumentException e)
{
System.out.println("exception");
}
System.out.println("Expected: exception");
}
}
-------------------------

Hint:

/**
This exception reports a negative initial balance on a bank account.
*/
public class NegativeBalanceException extends RuntimeException
{
public NegativeBalanceException()
{
}

public NegativeBalanceException(String message)
{
super(message);
}
}

Answer 1

Code For Above Problem:

BankAccount.java

/**
 * A bank account has a balance that can be changed by deposits and withdrawals.
 */
public class BankAccount {
        private double balance;

        /**
         * Constructs a bank account with a zero balance
         */
        public BankAccount() {
                balance = 0;
        }

        /**
         * Constructs a bank account with a given balance
         * 
         * @param initialBalance the initial balance
         */
        public BankAccount(double initialBalance) {
                if (initialBalance < 0)
                        throw new NegativeBalanceException("Cannot create account: " + initialBalance + " is less than zero");

                balance = initialBalance;
        }

        /**
         * Deposits money into the bank account.
         * 
         * @param amount the amount to deposit
         * @throws NegativeAmountException 
         */
        public void deposit(double amount) throws NegativeAmountException {
                if (amount < 0)
                        throw new NegativeAmountException("Deposit of " + amount + " is less than zero");
                double newBalance = balance + amount;
                balance = newBalance;
        }

        /**
         * Withdraws money from the bank account.
         * 
         * @param amount the amount to withdraw
         * @throws NegativeAmountException 
         * @throws InsufficientFundsException 
         */
        public void withdraw(double amount) throws NegativeAmountException, InsufficientFundsException {
                if (amount < 0)
                        throw new NegativeAmountException("Withdrawal of " + amount + " is less than zero");

                if (amount > balance)
                        throw new InsufficientFundsException("Withdrawal of " + amount + " exceeds balance of " + balance);

                double newBalance = balance - amount;
                balance = newBalance;
        }

        /**
         * Gets the current balance of the bank account.
         * 
         * @return the current balance
         */
        public double getBalance() {
                return balance;
        }
}

BankAccountTester2.java

/**
 * A class to test the BankAccount class.
 */
public class BankAccountTester2 {
        public static void main(String[] args) {
                BankAccount harrysChecking = new BankAccount();

                try {
                        harrysChecking.deposit(300);
                        System.out.println("success");
                } catch (IllegalArgumentException | NegativeAmountException e) {
                        System.out.println("exception");
                }
                System.out.println("Expected: success");

                try {
                        harrysChecking.withdraw(100);
                        System.out.println("success");
                } catch (IllegalArgumentException | NegativeAmountException | InsufficientFundsException e) {
                        System.out.println("exception");
                }
                System.out.println("Expected: success");

                try {
                        harrysChecking.deposit(-100);
                        System.out.println("success");
                } catch (IllegalArgumentException | NegativeAmountException e) {
                        System.out.println("exception");
                }
                System.out.println("Expected: exception");

                try {
                        harrysChecking.withdraw(300);
                        System.out.println("success");
                } catch (IllegalArgumentException | NegativeAmountException | InsufficientFundsException e) {
                        System.out.println("exception");
                }
                System.out.println("Expected: exception");
        }
}

NegativeBalanceException.java

/**
 * This exception reports a negative initial balance on a bank account.
 */
public class NegativeBalanceException extends RuntimeException {
        /**
         * 
         */
        private static final long serialVersionUID = 1L;

        public NegativeBalanceException() {
        }

        public NegativeBalanceException(String message) {
                super(message);
        }
}

NegativeAmountException.java

/**
 * This exception reports a negative amount on with draw or deposite
 */
public class NegativeAmountException extends Exception {

        /**
         * 
         */
        private static final long serialVersionUID = 1L;

        public NegativeAmountException() {
        }

        public NegativeAmountException(String message) {
                super(message);
        }
        
}

InsufficientFundsException.java

/**
 * This exception reports a InsufficientFund on with draw 
 */
public class InsufficientFundsException extends Exception {


        /**
         * 
         */
        private static final long serialVersionUID = 1L;

        public InsufficientFundsException() {
        }

        public InsufficientFundsException(String message) {
                super(message);
        }
}

Output Of BankAccountTester2:

success
Expected: success
success
Expected: success
exception
Expected: exception
exception
Expected: exception