(Subclasses of Account) In Programming Exercise 9.7, the Account class was defined to model a bank account. An account has the properties account number, balance, annual interest rate, and date created, and methods to deposit and withdraw funds

/*********************************************************************************
* (Subclasses of Account) In Programming Exercise 9.7, the Account class was     *
* defined to model a bank account. An account has the properties account number, *
* balance, annual interest rate, and date created, and methods to deposit and    *
* withdraw funds. Create two subclasses for checking and saving accounts. A      *
* checking account has an overdraft limit, but a savings account cannot be       *
* overdrawn.                                                                     *
*                                                                                *
* Draw the UML diagram for the classes and then implement them. Write            *
* a test program that creates objects of Account, SavingsAccount, and            *
* CheckingAccount and invokes their toString() methods.                          *
*********************************************************************************/
public class Exercise_11_03 {
	// Main method
	public static void main(String[] args) {
		// Create Account, SavingsAccount and Checking Account objects
		Account account = new Account(1122, 20000);
		SavingsAccount savings = new SavingsAccount(1001, 20000);
		CheckingAccount checking = new CheckingAccount(1004, 20000, -20);
		// Set annual interest rate of 4.5%
		account.setAnnualInterestRate(4.5);
		savings.setAnnualInterestRate(4.5);
		checking.setAnnualInterestRate(4.5);

		// Withdraw $2,500
		account.withdraw(2500);
		savings.withdraw(2500);
		checking.withdraw(2500);

		// Deposit $3,000
		account.deposit(3000);
		savings.deposit(3000);
		checking.deposit(3000);

		// Invoke toString methods
		System.out.println(account.toString());
		System.out.println(savings.toString());
		System.out.println(checking.toString());
	}
}

Account.java

/********************************************************
*                     Account                           *
*-------------------------------------------------------*
* -id: int                                              *
* -balance: double                                      *
* -annualInterestRate: double                           *
* ---------------------------                           *
* -dateCreated: String                                  *
* +Account()                                            *
* +Account(newid: int, newBalance: double)              *
* +setId(newId: int)                                    *
* +setBalance(newBalance: double)                       *
* +setAnnualInterestRate(newAnnualInterestRate: double) *
* +getId(): int                                         *
* +getBalance(): double                                 *
* +getAnnualInterestRate(): double                      *
* +getDateCreated(): String                             *
* +getMonthlyInterestRate(): double                     *
* +getMonthlyInterest(): double                         *
* +withdraw(amount: double)                             *
* +deposit(amount: double)                              *
********************************************************/

// Implement the Account class
import java.util.Date;

public class Account {
	// Data fields
	private int id;
	private double balance;
	private static double annualInterestRate;
	private Date dateCreated;

	// Constructors
	/** Creates a default account */
	Account() {
		this(0, 0); 
	}

	/** Creates an account with the specified id and initial balance */
	Account(int id, double balance) {
		this.id = id;
		this.balance = balance;
		annualInterestRate = 0;
		dateCreated = new Date();
	}

	// Mutator methods
	/** Set id */
	public void setId(int id) {
		this.id = id;
	}

	/** Set balance */
	public void setBalance(double balance) {
		this.balance = balance;
	}

	/** Set annualInterestRate */
	public void setAnnualInterestRate(double annualInterestRate) {
		this.annualInterestRate = annualInterestRate;
	}

	// Accessor methods
	/** Return id */
	public int getId() {
		return id;
	}

	/** Return balance */
	public double getBalance() {
		return balance;
	}

	/** Return annualInterestRate */
	public double getAnnualInterestRate() {
		return annualInterestRate;
	}

	/** Return dateCreated */
	public String getDateCreated() {
		return dateCreated.toString();
	}

	/** Return monthly interest rate */
	public double getMonthlyInterestRate() {
		return annualInterestRate / 12;
	}

	// Methods
	/** Return monthly interest */
	public double getMonthlyInterest() {
		return balance * (getMonthlyInterestRate() / 100);
	}

	/** Decrease balance by amount */
	public void withdraw(double amount) {
		balance -= amount;
	}

	/** Increase balance by amount */
	public void deposit(double amount) {
		balance += amount;
	}

	/** Return a String decription of Account class */
	public String toString() {
		return "\nAccount ID: " + id + "\nDate created: " + getDateCreated()
			+ "\nBalance: $" + String.format("%.2f", balance) + 
			"\nMonthly interest: $" + String.format("%.2f", getMonthlyInterest());
	}
}

CheckingAccount.java

/***************************************************************************
*                              CheckingAccount                             *
*--------------------------------------------------------------------------*
* -overdraftLimit: double                                                  *
* +CheckingAccount()                                                       *
* +CheckingAccount(newId: int, newBalance: double, overdraftLimit: double) *
* +setOverdraftLimit(overdraftLimit: double): void                         *
* +getOverdraftLimit(): double                                             *
* +withdraw(amount: double): boolean                                       *
* +toString(): String                                                      *
****************************************************************************/
// Implement Checking class
public class CheckingAccount
		extends Account {
	// Data fields
	private double overdraftLimit;

	/** Construct a default CheckingAccount object */
	public CheckingAccount() {
		super();
		overdraftLimit = -20;
	}

	/** Construct a CheckingAccout with specified id, balance and overdraftLimit */
	public CheckingAccount(int id, double balance, double overdraftLimit) {
		super(id, balance);
		this.overdraftLimit = overdraftLimit;
	}

	/** Set a new overdraft limit */
	public void setOverdraftLimit(double overdraftLimit) {
		this.overdraftLimit = overdraftLimit;
	}

	/** Return overdraft limit */
	public double getOverdraftLimit() {
		return overdraftLimit;
	}

	/** Decrease balance by amount */
	public void withdraw(double amount) {
		if (getBalance() - amount > overdraftLimit) {
			setBalance(getBalance() - amount);
		}
		else
			System.out.println("Error! Amount exceeds overdraft limit.");
	}

	/** Return a String decription of CheckingAccount class */
	public String toString() {
		return super.toString() + "\nOverdraft limit: $" + 
		String.format("%.2f", overdraftLimit);
	}
}

SavingsAccount.java

/*************************************
*          SavingsAccount            *
*------------------------------------*
* +SavingsAccount()                  *
* +withdraw(amount: double): boolean *
**************************************/
// Implement SavingsAccount class
public class SavingsAccount
		extends Account {
	
	/** Construct a default CheckingAccount object */
	public SavingsAccount() {
		super();
	}

	/** Construct a SavingsAccount with specified id, balance */
	public SavingsAccount(int id, double balance) {
		super(id, balance);
	}

	/** Decrease balance by amount */
	public void withdraw(double amount) {
		if (amount < getBalance()) {
			setBalance(getBalance() - amount);
		}
		else
			System.out.println(
				"Error! Savings account overdrawn transtaction rejected");
	}
}