Question

The Account class

Create a class named Account, which has the following private properties:

• number: long
• balance: double

Create a no-argument constructor that sets the number and balance to zero.

Create a two-parameter constructor that takes an account number and balance.

First, implement getters and setters: getNumber(), getBalance(), setBalance(double newBalance). There is no setNumber() -- once an account is created, its account number cannot change.

Now implement these methods: void deposit(double amount) and void withdraw(double amount). For both these methods, if the amount is less than zero, the account balance remains untouched. For the withdraw() method, if the amount is greater than the balance, it remains untouched.

Then, implement a toString() method that returns a string with the account number and balance, properly labeled.

The SavingsAccount class

This class inherits from Account and adds a private apr property, which is the annual percentage rate for interest. Write a no-argument constructor that sets the account number, balanace, and APR to zero. Write a three-argument constructor that takes an account number, balance, and interest rate as a decimal (thus, a 3.5% interest rate is given as 0.035).

Modify toString() to include the interest rate.

Add a getter and setter method for apr. The setter should leave the APR untouched if given a negative value.

Write a calculateInterest() method that returns the annual interest, calculated as the current balance times the annual interest rate.

The CreditCardAccount class

This class inherits from Account and adds a private apr property, which is the annual interest rate charged on the balance. It also has a private creditLimit property (double) which gives the credit limit for the card. Write a no-argument constructor that sets all the properties to zero. Write a four-argument constructor that takes an account number, balance, interest rate as a decimal (thus, a 3.5% interest rate is given as 0.035), and credit limit. Write getters and setters for the apr and creditLimit.

Modify toString() to include the interest rate and credit limit.

Override the withdraw() function so that you can have a negative balance. If a withdrawal would push you over the credit limit, leave the balance untouched. Examples:

• If your balance is $300 with a credit limit of $700, you can withdraw $900 (leaving a balance of $-600).
• If your balance is $-300 with a credit limit of $700, you can withdraw $350 (leaving a balance of $-650).
• If your balance is $-300 with a credit limit of $700, you can not withdraw $500, because that would then owe $800, which is more than your $700 limit.

In short, the maximum amount you can withdraw is your current balance plus the credit limit.

Add a calculatePayment() method that works as follows:

• If the balance is positive, the minimum amount you have to pay on your card per month is zero.
• Otherwise, your monthly payment is the minimum of 20 and (???/12)⋅(−???????)(apr/12)⋅(−balance)(???/12)⋅(−???????)(apr/12)⋅(−balance)

The Test Program

Write a program named TestAccounts that creates an array of five Account objects:

• An Account number 1066 with a balance of $7,500.
• A SavingsAccount number 30507 with a balance of $4,500 and an APR of 1.5%
• A CreditCardAccount number 51782737 with a balance of $7,000.00, APR of 8%, and credit limit of $1000.00
• A CreditCardAccount number 629553328 with a balance of $1,500.00, an APR of 7.5%, and a credit limit of $5,000
• A CreditCardAccount number 4977201043 with a balance of -$5,000.00, an APR of 7%, and a credit limit of $10,000

Your program will use a loop to do the following for each account:

• Deposit $2,134.00
• Withdraw $4,782.00
• Print the account status using toString().
  • For savings accounts, also display the annual interest
  • For credit card accounts, also display the monthly payment

Here is some sample output:

Account: 1066
Balance: $4852.00

Account: 30507
Balance: $1852.00
Interest Rate: 1.50%
Annual Interest: $27.78

Account: 51782737
Balance: $4352.00
Interest Rate: 8.00%
Credit Limit: $1000.00
Monthly Payment: $0.00

Account: 629553328
Balance: $-1148.00
Interest Rate: 7.50%
Credit Limit: $5000.00
Monthly Payment: $7.18

Account: 4977201043
Balance: $-7648.00
Interest Rate: 7.00%
Credit Limit: $10000.00
Monthly Payment: $20.00

Put the Account, SavingsAccount, and CreditCardAccount classes in the TestAccounts.java file rather than creating separate files. Please submit only one file. Upload the TestAccounts.java file here.

Answer 1

public class TestAccounts {
  
   public static void main(String[] args) {
      
       // creating an array of five Account objects
       Account accounts[] = {new Account(1066,7500),
               new SavingsAccount(30507,4500,0.015),
               new CreditCardAccount(51782737,7000,0.08,1000),
               new CreditCardAccount(629553328,1500,0.075,5000),
               new CreditCardAccount(4977201043L,-5000,0.07,10000)};
      
       //using a loop to deposit, withdraw and print for each account
       for(int i=0; i<accounts.length; i++) {
           accounts[i].deposit(2134);
           accounts[i].withdraw(4782);
           System.out.println("\n" + accounts[i].toString());          
       }
      
   }

   // --------------------------Account class--------------------------------
   public static class Account {
       private long number;
       private double balance;
      
       public Account() {
           number = 0;
           balance = 0;
       }
      
       public Account(long number, double balance) {
           this.number = number;
           this.balance = balance ;
       }
      
       public long getNumber() {
           return number;
       }
      
       public double getBalance() {
           return balance;
       }
      
       public void setBalance(double newBalance) {
           balance = newBalance;
       }
      
       public void deposit(double amount) {
           if(amount >= 0)                           // else leave account intact
               balance += amount;
       }
       public void withdraw(double amount) {
           if(amount >= 0 && amount <= balance)    // else leave account intact
               balance -= amount;
       }
      
       public String toString() {
           return "Account: " + number + "\nBalance: $" + String.format("%.2f",balance);
       }  
      
   }
  
   // --------------------------SavingsAccount class--------------------------------
   public static class SavingsAccount extends Account{
       private double apr;
      
       public SavingsAccount() {
       super(0,0);                // Parent constructor
           apr = 0;
       }
       public SavingsAccount(long number, double balance, double apr) {
       super(number,balance);        // Parent constructor
           this.apr = apr;
       }
      
       public String toString() {
           return super.toString() + "\nInterest Rate: " + String.format("%.2f",apr*100) + "%";
       }
      
       public double getApr() {
           return apr;
       }
      
       public void setApr(double apr) {
           if(apr>=0)                   // else leave account intact
               this.apr = apr;
       }
      
       public double calculateInterest() {
           return getBalance() * apr;
       }
      
   }
  
   // --------------------------CreditCardAccount class--------------------------------
   public static class CreditCardAccount extends Account{
       private double apr;
       private double creditLimit;
      
       public CreditCardAccount() {
           super(0,0);                // Parent constructor
           apr = 0;
           creditLimit = 0;
       }
      
       public CreditCardAccount(long number, double balance, double apr, double creditLimit) {
       super(number,balance);
           this.apr = apr;
           this.creditLimit = creditLimit;
       }
      
       public double getApr() {
           return apr;
       }
      
       public void setApr(double apr) {
           this.apr = apr;
       }
      
       public double getCreditLimit() {
           return creditLimit;
       }
      
       public void setCreditLimit(double creditLimit) {
               this.creditLimit = creditLimit;
       }
       public String toString() {
           return super.toString() +
                   "\nInterest Rate: " + String.format("%.2f",apr*100) + "%" +
                   "\nCredit Limit: $" + creditLimit +
                   "\nMonthly Payment: $" + String.format("%.2f",calculatePayment());
       }
       @Override
       public void withdraw(double amount) {
           if(amount >=0 ) {                               // else leave account intact
               double withdrawLimit = getBalance() + creditLimit;
               if(amount <= withdrawLimit)                   // else leave account intact
                   setBalance( getBalance() - amount );
           }

       }
      
       public double calculatePayment() {
           if(getBalance() > 0)
               return 0;
           else
               return Math.min( 20, (apr/12) * -getBalance() ); // choose the smallest of the two
       }  
   }
} // TestAccounts class

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