Question

The following java files are created from this:

• BankAccount.java
• CheckingAccount.java
• SavingsAccount.java
• TransactionDriver.java

Objective: To learn about inheritance and understand how to inherit and override superclass methods and to be able to invoke superclass constructors

In this assignment we will simulate a bank transactions that offers the customer the following types:

1. Checking account that does not provide interest, but it does provide a limited free transactions per month. Additional checking account transactions are charged a small fee.
2. Savings account that earns interest on a monthly basis.

Program Specification and implementation

Create a superclass BankAccount and two subclasses CheckingAccount and SavingsAccount. All the bank accounts should support getBalance, deposit and withdraw methods. Follow the below detailed specifications for each class.

BankAccount:

-         Implement instance field balance

-         Constructor creates an account with 0 balance.

-         Constructor to create an account with an initial balance

-         deposit method that takes in amount to be deposited

-         withdraw method that takes amount to withdraw

-         getBalance method to return the current balance in the account.

-         transferMoney method that transfers money from this bank account to other bank account. This method takes two arguments (BankAccount otherAccount, double amount)

-         display method that displays the account balance.

CheckingAccount:

-        Constant instance fields for ALLOWED_TRANS and TRANS_FEE. Allow for 2 free transactions and $3 for additional transaction.

-         instance field transactionCount (specific and new to CheckingAccount).

-         Constructor to create zero balance account.

-         Constructor to create an account with an initial balance

-         override deposit and withdraw methods in order to increment the transaction count.

-         chargeFees that charges transaction fee if any to the account at the end of the period.

SavingsAccount:

-         Instance field interestRate that holds the interest rate for period.

-         Constructor that sets interest rate.

-         Constructor that sets rate and initial balance.

-         addCompoundInterest method that adds the interest for the current period to the account balance. Deposit the interest to the account. Use this formula to calculate interest = balance * interestRate / 100.0.

TransactionsDriver:

-         Instantiate a savings account name it dadsSavings with interestRate 0.3%

-         Instantiate a checking account and name it kidsChecking.

-         Deposit 10000 into dadsSavings account.

-        Transfer 3000 to kidsChecking

-        Withdraw 200 from kidsChecking

-         Withdraw 400 from kidsChecking

-         Withdraw 300 from kidsChecking

-        Withdraw 500 from kidsChecking

-         Withdraw 400 from kidsChecking

-         Invoke end of period interest for the savings account

-        Invoke end of period transactions fees for the checking account

-        Display the final balance for dadsSavings account

-         Display the final balance for kidsChecking account

-         End of program

Sample Output:

At the end of these transactions the bank accounts should have the below balances

End of the period account balances

Dad's savings. Account balance: 7021.0

kid's checking. Account balance: 1188.0

Also, draw the inheritance UML diagram for the three bank accounts classes.

Answer 1

BankAccount.java

==========================

package bank;

public class BankAccount {
   // instance field
   protected double balance;
  
   // constructors
   // create an account with 0 balance
   public BankAccount() {
       balance = 0;
   }
  
   // create an account with given amount of balance
   public BankAccount(double amount){
       balance = amount;
   }
  
   // takes in amount to be deposited and add it to balance
   public void deposit(double amount) {
       balance = balance + amount;
   }
  
   // takes amount to withdraw and removes that amount from balance
   public void withdraw(double amount) {
       balance = balance - amount;
   }
  
   // return the current balance in the account
   public double getBalance() {
       return balance;
   }
  
   // transfers money from this bank account to other bank account
   public void transferMoney(BankAccount otherAccount, double amount) {
       // remove money from this bank account
       this.withdraw(amount);
       // add money to other bank account
       otherAccount.deposit(amount);
   }
  
   // displays the account balance
   public void display() {
       System.out.printf("Account balance: %.2f", balance);
       System.out.println();
   }

}

===========================

CheckingAccount.java

===========================

package bank;

public class CheckingAccount extends BankAccount{
  
   // instance fields
   private final int ALLOWED_TRANS = 2;
   private final int TRANS_FEE = 3;
   private int transactionCount;
  
   // constructors
   // constructor to create zero balance account.
   public CheckingAccount() {
       super(); // call to parent class constructor
       transactionCount = 0;
   }
  
   // constructor to create an account with an initial balance
   public CheckingAccount(double amount) {
       super(amount); // call to parent class constructor
       transactionCount = 0;
   }
  
   // override method to increment the transaction count
   @Override
   public void deposit(double amount) {
       // call parent class method for deposit
       super.deposit(amount);
       // increase transaction counts
       transactionCount++;
   }
  
   // override method to increment the transaction count
   @Override
   public void withdraw(double amount) {
       // call parent class method for deposit
       super.withdraw(amount);
       // increase transaction counts
       transactionCount++;
   }
      
   // charges transaction fee if any to the account at the end of the period
   public void chargeFees() {
       // check for the transaction counts
       if(transactionCount > ALLOWED_TRANS) {
           // charge fees for more transactions
           double charge = (transactionCount - ALLOWED_TRANS)*TRANS_FEE;
           // update balance
           this.balance = this.balance - charge;
       }
   }

}

============================

SavingsAccount.java

============================

package bank;

public class SavingsAccount extends BankAccount{
  
   // Instance field
   private double interestRate;
  
   // constructors
   // constructor that sets interest rate
   public SavingsAccount(double rate) {
       super(); // call to parent class constructor
       interestRate = rate;
   }
  
   // constructor that sets rate and initial balance
   public SavingsAccount(double rate, double amount) {
       super(amount); // call to parent class constructor
       interestRate = rate;
   }
  
   // adds the interest for the current period to the account balance
   public void addCompoundInterest() {
       // calculate interest
       double interest = this.balance * interestRate / 100.0;
       // deposit the interest to the account
       this.deposit(interest);
   }
  
}

==================================

TransactionsDriver.java

==================================

package bank;

public class TransactionsDriver {
  
   // main method to run the program
   public static void main(String[] args) {
       // Instantiate a savings account name it dadsSavings with interestRate 0.3%
       SavingsAccount dadsSavings = new SavingsAccount(0.3);
      
       // Instantiate a checking account and name it kidsChecking
       CheckingAccount kidsChecking = new CheckingAccount();
      
       // Deposit 10000 into dadsSavings account.
       dadsSavings.deposit(10000);
      
       // Transfer 3000 to kidsChecking
       dadsSavings.transferMoney(kidsChecking, 3000);
      
       // Withdraw 200 from kidsChecking
       kidsChecking.withdraw(200);
      
       // Withdraw 400 from kidsChecking
       kidsChecking.withdraw(400);
      
       // Withdraw 300 from kidsChecking
       kidsChecking.withdraw(300);
      
       // Withdraw 500 from kidsChecking
       kidsChecking.withdraw(500);
      
       // Withdraw 400 from kidsChecking
       kidsChecking.withdraw(400);
      
       // Invoke end of period interest for the savings account
       dadsSavings.addCompoundInterest();
      
       // Invoke end of period transactions fees for the checking account
       kidsChecking.chargeFees();
      
       // Display the final balance for dadsSavings account
       System.out.print("Dad's savings. ");
       dadsSavings.display();
       // Display the final balance for kidsChecking account
       System.out.print("kid's checking. ");
       kidsChecking.display();
   }

}

let me know if you have any doubts or problem.