Design an abstract class named BankAccount to hold the following data for a bank
ID: 3559261 • Letter: D
Question
Design an abstract class named BankAccount to hold the following data for a bank account:
-Account Name & Number
-Balance
-Number of deposits this month
-Number of withdrawals
-Annual interest rate
-Monthly service charges
The class should have the following methods:
Constructor:
The constructor should accept arguments for the balance and annual interest rate.
Deposit:
A method that accepts an argument for the amount of the deposit. The method should add the argument to the account balance. It should also increment the variable holding the number of deposits.
Withdraw:
A method that accepts an argument for the amount of the withdrawal. The method should subtract the argument from the balance. It should also increment the variable holding the number of withdrawals.
calcInterest:
A method that updates the balance by calculating the monthly interest earned by the account, and adding this interest to the balance. This is performed by the following formulas:
Monthly Interest Rate = (Annual Interest Rate / 12)
Monthly Interest = Balance * Monthly Interest Rate
Balance = Balance + Monthly Interest
monthlyProcess:
A method that subtracts the monthly service charges from the bal- ance, calls the calcInterest method, and then sets the variables that hold the number of withdrawals, number of deposits, and monthly service charges to zero.
Next, design a SavingsAccount class that extends the BankAccount class. The SavingsAccount class should have a status field to represent an active or inactive account. If the balance of a savings account falls below $25, it becomes inactive. (The status field could be a boolean variable.) No more withdrawals can be made until the balance is raised above $25, at which time the account becomes active again. The savings account class should have the following methods:
withdraw:
A method that determines whether the account is inactive before a withdrawal is made. (No withdrawal will be allowed if the account is not active.) A withdrawal is then made by calling the superclass version of the method.
deposit:
A method that determines whether the account is inactive before a deposit is made. If the account is inactive and the deposit brings the balance above $25, the account becomes active again. The deposit is then made by calling the superclass version of the method.
monthlyProcess:
Before the superclass method is called, this method checks the number of withdrawals. If the number of withdrawals for the month is more than 4, a service charge of $1 for each withdrawal above 4 is added to the superclass field that holds the monthly ser- vice charges. (Don
Explanation / Answer
An instance cannot be created for an abstract class. What can be done is, the sub-class which is using the methods and variables of the base class, can have an instance or object. Hence, in the given program, create an object to SavingsAccount class. The methods of the BankAccount class are invoked in the SavingsAcoount class using the "super" keyword.
P.S.
Modified Code is highlighted in bold and italics.
The underlined part of code can be removed. It is only added to show the execpution of program!
public class Bank
{
public static void main(String args[])
{
SavingsAccount sa=new SavingsAccount(4501,12.2);
sa.withdraw(120);
sa.deposit(33);
sa.monthlyProcess();
}
}
Executed Program Code:
public class Bank
{
public static void main(String args[])
{
SavingsAccount sa=new SavingsAccount(4501,12.2);
sa.withdraw(120);
sa.deposit(33);
sa.monthlyProcess();
}
}
abstract class BankAccount
{
// data members
protected double balance;
protected int numOfDeposits;
protected int numOfWithdrawals;
protected double interestRate;
protected double serviceCharge;
// 2-argument constructor
public BankAccount(double bal, double intRate)
{
balance = bal;
interestRate = intRate;
}
// Deposits amount into the account
public void deposit(double amount)
{
balance += amount;
numOfDeposits++;
System.out.println(" After deposit :"+balance);
}
// Withdrawals amount from the account
public void withdraw(double amount)
{
balance -= amount;
numOfWithdrawals++;
System.out.println(" After withdraw: "+balance);
}
// Calculates monthly interest and adds it to the main balance
public void calcInterest()
{
double monthlyInterestRate = interestRate / 12;
monthlyInterestRate = balance * monthlyInterestRate;
balance = balance + monthlyInterestRate;
}
// less the service charges from the balance
// and clears number of withdrawals and deposits.
public void monthlyProcess()
{
balance = balance - serviceCharge;
calcInterest();
numOfDeposits = 0;
numOfWithdrawals = 0;
serviceCharge = 0;
}
}
class SavingsAccount extends BankAccount
{
// account status
private boolean status;
// 2-argument constructor
// calls base class constructor
// and sets account status based on balance
public SavingsAccount(double balance, double interestRate)
{
super(balance, interestRate);
if (balance < 25)
status = false;
else
status = true;
}
// allows withdrawal if the account is active
// otherwise denies
public void withdraw(double amount)
{
if (status)
super.withdraw(amount);
else
System.out.println("Account is inactive");
}
// deposits amount into the account by calling
// base class deposit method and sets status
public void deposit(double amount)
{
super.deposit(amount);
if (balance > 24)
status = true;
}
// sets service charge based on number of withdrawals
// and process monthly charges updates account status
public void monthlyProcess()
{
if (numOfWithdrawals > 4)
serviceCharge = (numOfWithdrawals - 4);
super.monthlyProcess();
if (balance < 25)
status = false;
}
}
Sample Output:
After withdraw: 4381.0
After deposit: 4414.0
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