Exercise 5 w/ solution

Creating Subclasses of Bank Accounts

In this exercise, you will create two subclasses of the Account class in the Banking project: SavingsAccount and CheckingAccount.

To the banking package, add the SavingsAccount and CheckingAccount subclasses, as modeled in the illustration

1. Create the banking directory. Copy the previous Banking project files in this package directory.

Modify the Account Class

In the UML diagram, the Account class has changed: The balance attribute is now protected (indicated by the # character instead of the – character).

2. Change the access mode of the balance attribute to protected.

Modify the SavingsAccount Class

Implement the SavingsAccount class, as modeled in the illustration.

3. The SavingsAccount class must extend the Account class.
4. It must include an interestRate attribute with type double.
5. It must include a public constructor that takes two parameters: balance and interest_rate. This constructor must pass the balance parameter to the parent constructor by calling super (balance).

Modify the Checking Account Class

Implement the CheckingAccount class, as modeled in the illustration

6. The CheckingAccount class must extend the Account class.
7. It must include an overdraftProtection attribute with type double.
8. It must include one public constructor that takes one parameter: balance. This constructor must pass the balance parameter to the parent constructor by calling super(balance).
9. It must include another public constructor that takes two parameters: balance and protect. This constructor must pass the balance parmeter to the parentconstructor by calling super(balance) and set the overdraftProtection attribute.
10. The CheckingAccount class must override the withdraw method. It must perform the following check: If the current balance is adequate to cover the amount to withdraw, then proceed as usual. If not and if there is overdraft protection, then attempt to cover the difference (balance – amount) by value of the overdraftProtection. If the amount needed to cover the overdraft is greater than the current level of protection, then the whole transaction must fail with the checking balance unaffected.

Test the code

In the main exercise directory, compile and execute the TestBanking program. The output should be:

Creating the customer Jane Smith.

Creating her Savings Account with a 500.00 balance and 3% interest.

Creating the customer Owen Bryant.

Creating his Checking Account with a 500.00 balance and no overdraft proctection.

Creating the customer Tim Soley.

Creating his Checking Account with a 500.00 balance and 500.00 in overdraft protection.

Creating the customer Maria Soley.

Maria shares her Checking Account with her husband Tim.

Retrieving the customer Jane Smith with her savings account.

Withdraw 150.00: true

Deposit 22.50: true

Withdraw 47.62: true

Withdraw 400.00: false

Customer [Simss, Jane] has a balance of 324.88

Retrieving the customer Owen Bryant with his checking account with no overdraft protection.

Withdraw 150.00: true

Deposit 22.50: true

Withdraw 47.62: true

Withdraw 400.00: false

Customer [Bryant, Owen] has a balance of 324.88

Retrieving the customer Tim Soley with his checking account that has overdraft protection.

Withdraw 150.00: true

Deposit 22.50: true

Withdraw 47.62: true

Withdraw 400.00: true

Customer [Soley, Tim] has a balance of 0.00

Retrieving the customer Maria Soley with her joint checking account with husband Tim.

Withdraw 150.00: true

Deposit 750.00: false

Customer [Soley, Maria] has a balance of 150.00

Jane’s savings account and Owen’s checking account fundamentally behave as a plain-old bank account. But Tim and Maria’s joint checking account has 500.00 worth of overdraft protection. Tim’s transactions dip into that protection and therefore his ending balance is 0.00. His account’s overdraft protection level is 424.88. Finally, Maria deposits 150.00 into this joint account; raising the balance from 0.00 to 150.00. Then she tries to withdraw 1000.00, which fails because neither the balance nor the overdraft protection can cover that requested amount.

SOLUTION:

CheckingAccount.

import banking.*;
public class CheckingAccount extends Account{
private double overdraftProtection;

public CheckingAccount(double balance) {
super(balance);
}
public CheckingAccount(double balance, double protect){
super(balance);
overdraftProtection=protect;

}
public boolean withdraw (double amt)
{

if (super.balance>=amt){
balance = balance - amt;
return true;

}
else if (amt>super.balance && amt>overdraftProtection){
return false;
}
else if (amt>super.balance && amt overdraftProtection = super.balance - amt;
super.balance = 0;
return true;
}

return super.balance }

}

SavingsAccount:

import banking.*;
public class SavingsAccount extends Account
{
private double interestRate;

public SavingsAccount (double balance, double interest_rate){
super(balance);
interestRate = interest_rate;
}
}

Account:

public class Account {
protected double balance;

public Account(double init_balance){
balance = init_balance;
}

public double getBalance(){
return balance;
}
public boolean deposit(double amt)
{

balance = balance + amt;
return true;


}
public boolean withdraw (double amt)
{
if (balance>amt){
balance = balance - amt;
return true;
}
else
{
return false;
}
}
}