[JAVA] Part 1 Create a class SavingsAccount. Use a static class variable to stor

Question

[JAVA]

Part 1

Create a class SavingsAccount. Use a static class variable to store the annualInterestRate for each of the savers. Each object of the class contains a private instance variable savingsBalance indicating the amount the saver currently has on deposit. Provide method calculateMonthlyInterest to calculate the monthly interest by multiplying the balance by annualInterestRate divided by 12; this interest should be added to savingsBalance. Provide a static method modifyInterestRate that sets the annualInterestRate to a new value. Write a driver program to test the class SavingsAccount. Instantiate two different savingsAccount objects, saver1 and saver2, with balances of $2000.00 and $3000.00, respectively. Set annualInterestRate to 4%, then calculate the monthly interest and print the new balances for each of the savers. Then set the annualInterestRate to 5% and calculate the next months interest and print the new balances for each of the savers.

Part 2

Write another class SpecialSavings that extends SavingsAccount to pay interest of 10% on accounts that have balances that exceed 10K. Also provided methods to deposit and take money out of savings account. Write a driver program to test the class SpecialSavings. Instantiate two different savingsAccount objects, saver1 and saver2, with balances of $2000.00 and $3000.00, respectively. Make a few deposits and withdrawals and show balance and interest earned for each account.

SpecialSavings a1 = new SpecialSavings();

a1.deposit(5000);

a1.calculateMonthlyInterest(); //pays 4%

a1.deposit(10000);

a1.calculateMonthlyInterest(); //pays 10%

calculateMonthlyInterest() method is overridden.

Some Tips for helping you with Part 1 :

Pl. follow the instructions in the assignment and write the class definition. A driver program is the code you would write in main() to exercise the code of class definition. You should declare private variable in your class definition. You should also write protected methods to set and get the value of private variables.

For part 2 -

You need to write deposit and withdrawal methods. Should you put this in parent class or child class? Try to answer this question so that you have most reusability in your class definition. In this part - you have to learn how polymorphism works. You will have accounts whose balance might be above or below 10K. By using methods in both classes try to change the interest earned to 10% if balance is above 10K or 4% if the interest is lower.

Explanation / Answer

public class SavingsAccount { private static double annualInterestRate; private double savingsBalance; protected SavingsAccount() { savingsBalance = 0; annualInterestRate = 0; } protected SavingsAccount(double balance) { savingsBalance = balance; annualInterestRate = 0; } protected void calculateMonthlyInterest() { System.out.println("Current savings balance: " + savingsBalance); double monthlyInterest; monthlyInterest = (savingsBalance * annualInterestRate)/12; savingsBalance += monthlyInterest; System.out.println("New savings balance: " + savingsBalance); } protected double getBalance() { return savingsBalance; } protected static void modifyInterestRate(double newInterestRate) { annualInterestRate = newInterestRate; } } class SpecialSavings extends SavingsAccount { protected static void modifyInterestRate() { if(SavingsAccount.getBalance() > 10000) { modifyInterestRate(.1); } } } class Driver { public static void main(String[] args) { SavingsAccount saver1 = new SavingsAccount(2000); SavingsAccount saver2 = new SavingsAccount(3000); saver1.modifyInterestRate(.04); saver1.calculateMonthlyInterest(); saver2.modifyInterestRate(.04); saver2.calculateMonthlyInterest(); saver1.modifyInterestRate(.05); saver1.calculateMonthlyInterest(); saver2.modifyInterestRate(.05); saver2.calculateMonthlyInterest(); } }

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