Question

JAVA

Create a class called SavingsAccount. The class should have a static variable named, annualInterestRate, to store the annual interest rate for all account holders. Each object of the class should contain a private instance variable named, savingsBalance, indicating the amount the saver currently has on deposit.

Write methods to perform the following:

• calculateMonthlyInterest – calculates the monthly interest by multiplying the savingsBalance by annualInterestRate divided by 12. This interest should be added to the balance.

• depositAmount – allows the customer to deposit money into the account (thereby increasing the balance. Do not accept negative amount.

• withdrawAmount – allows the customer to withdraw money from the account (thereby decreasing the balance. Do not accept negative amount.

• modifyInterestRate (static) – allows the bank to change the annual interest rate. Accept only floating-point values between 2 and 5.

• toString – get string representation of SavingsAccount object (prints the variable, savingsBalance

  Write a test class named TestSvingsAccount to test the SavingsAccount class. Instantiate two objects, saver1 and saver2, with balances of $2000.00 and $3000.00, respectively. Set the annual interest rate to 4%, then calculate the monthly interest for each of the 12 months and print the new balance, at the end of each month, for both savers.

  Deposit $1500.00 to saver1’s account and withdraw $550.00 from saver2’s account. Next change the annual interest rate to 5%, calculate the next month’s interest and print the new balance for both savers.

  No input, processing or output should happen in the main method. All work in the test class should be delegated to other methods in the class. Include the recommended minimum documentation for each method. See the program one template for more details.

  All methods not indicated as static should be non-static.

Answer 1

// SavingsAccount.java
public class SavingsAccount {

   private static double annualInterestRate=0;
   private double savingsBalance;
  
   // constructor that initializes the initial balance for the account
   public SavingsAccount(double balance)
   {
       savingsBalance = balance;
   }
  
   // method to calculate and update the balance with the monthly interest
   public void calculateMonthlyInterest()
   {
       savingsBalance += ((savingsBalance*annualInterestRate)/12);
   }
  
   // method to deposit an amount in the account
   public void depositAmount(double amount)
   {
       // check that the amount is not negative, else ignore the deposit
       if(amount >= 0)
           savingsBalance += amount;
   }
  
   // method to withdraw an amount from the account
   public void withdrawAmount(double amount)
   {
       // check that the amount is not negative, else ignore the withdrawal
       if(amount >=0)
           savingsBalance -= amount;
   }
  
   // method to update the annual interest rate with the passed value
   public static void modifyInterestRate(double interestRate)
   {
       // check that the value of the parameter is between [2,5] then update else ignore the updation
       if(interestRate >= 2 && interestRate <= 5)
           annualInterestRate = interestRate;
   }
  
   // method to return string representation of the account
   public String toString()
   {
       return "$"+String.format("%.2f",savingsBalance);
   }
      
}
//end of SavingsAccount.java

// TestSvingsAccount.java : Java test class to test the SavingsAccount class
public class TestSvingsAccount {
  
   // method to test the savings account class
   public void tester1()
   {
       SavingsAccount saver1, saver2;
       // create both the accounts
       saver1 = new SavingsAccount(2000);
       saver2 = new SavingsAccount(3000);
      
       // update the annual interest rate
       SavingsAccount.modifyInterestRate(4);
      
       // loop to calculate monthly interest and display the balance at the end of month for 12 months for saver1
       for(int i=0;i<12;i++)
       {
           saver1.calculateMonthlyInterest();
           System.out.printf("\nBalance at the end of month-%d for saver1 : %s",i+1,saver1);
       }
       // loop to calculate monthly interest and display the balance at the end of month for 12 months for saver1

       System.out.println();
       for(int i=0;i<12;i++)
       {
           saver2.calculateMonthlyInterest();
           System.out.printf("\nBalance at the end of month-%d for saver2 : %s",i+1,saver2);
       }
      
       System.out.println();
       // update saver1 and saver2  
saver1.depositAmount(1500);
       saver2.withdrawAmount(550);
       // update annual interest rate
       SavingsAccount.modifyInterestRate(5);
      
       saver1.calculateMonthlyInterest();
       System.out.println("\nBalance at the end of next month for saver1 : "+saver1);
       saver2.calculateMonthlyInterest();
       System.out.println("Balance at the end of next month for saver2 : "+saver2);

   }

   public static void main(String[] args) {

       TestSvingsAccount test = new TestSvingsAccount ();
       test.tester1(); // call the method to test the class
   }

}
//end of TestSvingsAccount.java

Output: