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).

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. Modify toString() to include the interest rate and annual interest.

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.

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)⋅(−???????)

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

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()

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

Answer 1

Account.java

public class Account {
private long number;
private double balance;

public Account(){
number = 0;
balance = 0.0;
}
  
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 balance) {
this.balance = balance;
}

public void deposit(double amt)
{
if(amt > 0)
balance += amt;
}
  
public void withdraw(double amt)
{
if(amt < balance)
balance -= amt;
}
  
@Override
public String toString() {
return "Account number=" + number + "\nBalance=" + balance;
}
  
  
}

SavingsAccount.java

public class SavingsAccount extends Account{
private double apr;

public SavingsAccount() {
super(); // calls the no-arg constructor of Account class
apr = 0.0;
}

public SavingsAccount(long number, double balance, double apr) {
super(number, balance); // calls the 2-arg constructor of Account class
this.apr = apr/100;
}

public double getApr() {
return apr;
}
  
public double calculateInterest(){
return apr * (super.getBalance());
}

@Override
public String toString() {
return super.toString() + "\nAnnual rate of Interest: " + apr*100 + "%\nAnnual interest: " + this.calculateInterest();
}
  
  
}

CreditCardAccount.java

public class CreditCardAccount extends Account{
private double apr;
private double creditLimit;
  
public CreditCardAccount(){
super(); // calls the no-arg constructor of Account class
this.apr = 0.0;
this.creditLimit = 0.0;
}

public CreditCardAccount(long number, double balance, double apr, double creditLimit) {
super(number, balance);
this.apr = apr/100;
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;
}
  
@Override
public void withdraw(double amt)
{
if(amt < (super.getBalance() + creditLimit))
{
// if the sum of credit limit and balance is less than the amount to withdraw, you can withdraw
super.setBalance(super.getBalance() - amt);
}
}
  
public double calculatePayment(){
double amount;
  
if(super.getBalance() > 0)
amount = 0;
else
amount = 20 + ((this.apr / 12) * (-super.getBalance()));
  
return amount;
}
  
@Override
public String toString(){
return super.toString() + "\nAnnual rate of interest: " + this.apr * 100 + "%\nCredit Limit: " + this.creditLimit + "\nMonthly payment: " + this.calculatePayment();
}
  
}

TestAccounts.java

public class TestAccounts {
public static void main(String... args){
Account[] accounts = new Account[5];
// since Account is the super class of SavingsAccount and CreditCardAccount
// it can hold the instances of SavingsAccount and CreditCardAccount
  
accounts[0] = new Account(1066, 7500);
accounts[1] = new SavingsAccount(30507, 4500, 1.5);
accounts[2] = new CreditCardAccount(51782737, 7000,8,1000);
accounts[3] = new CreditCardAccount(629553328, 1500, 7.5, 5000);
accounts[4] = new CreditCardAccount(497720104, -5000, 7, 10000);
  
// this is a foreach loop, it will take out objects from accounts array one by one
// store them in variable "account" and performs operations on them
  
for(Account account : accounts)
{
account.deposit(2134);
account.withdraw(4782);
  
System.out.println(account);
System.out.println();
}
  
}
}