Question

Problem 1:
In java

Create a program to calculate interest rate and total balance - the program consists of

(a) A class that encapsulates the interest rate and total balance calculation

• Constructor should accept initial balance and interest rate
• Methods:
  • Returns interest rate
  • Returns total balance
  • Set interest rate
  • Set initial balance

(b) A test program that uses class from step (A) to perform the following:

• Set interest rate to 5% and initial balance to 1000
• Print interest amount and total balance
• Increase interest rate to 10%
• Print interest amount and total balance
• Increase initial balance to 2000
• Print interest amount and total balance

Answer 1

(a)

//Account.java
public class Account
{
   //variables to store total balance and interest rate
   private double total_balance;
   private double interest_rate;
   /*Constructor to set total balance and interest rate value*/
   public Account(double initial_balance, double interest_rate)
   {
       this.total_balance=initial_balance;
       //convert interest_rate to decimal value
       this.interest_rate=interest_rate/100.0;
   }

   public void setInterest_rate(double interest_rate)
   {
       this.interest_rate = interest_rate/100.0;
   }
  
   public void setInitial_balance(double initial_balance)
   {
       this.total_balance = initial_balance;
   }
   /*Return interest value to integer value*/
   public double getInterest_rate()
   {
       return interest_rate*100.0;
   }
   public double getInterestAmount()
   {
       return total_balance*interest_rate;
   }
   /**The method getTotalBalance returns the total balance */
   public double getTotalBalance()
   {
       total_balance=total_balance+ getInterestAmount();
       return total_balance;
   }
} //end of the class Account

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(b)

/* * The java program that creates an instance of Account class with initial balance and interest rate.

Then print the rate of interest, interest amount and total balance .* */

//TestProgram.java
public class TestProgram
{
   public static void main(String[] args)
   {
       //Set interest rate to 5% and initial balance to 1000
       Account account= new Account(1000, 5);
      
       System.out.printf("Interest rate : %.2f %%\n",account.getInterest_rate());
       //Print interest amount and total balance
       System.out.printf("Interest amount : %.2f Total Balance: %.2f\n",
               account.getInterestAmount(),account.getTotalBalance());
      
       //Increase interest rate to 10%
       account.setInterest_rate(10);
       System.out.printf("Interest rate : %.2f %%\n",account.getInterest_rate());
       //Print interest amount and total balance
       System.out.printf("Interest amount : %.2f Total Balance: %.2f\n",
               account.getInterestAmount(),account.getTotalBalance());
      
      
       //Increase initial balance to 2000
       account.setInitial_balance(2000);
       System.out.printf("Interest rate : %.2f %%\n",account.getInterest_rate());
       //Print interest amount and total balance
       System.out.printf("Interest amount : %.2f Total Balance: %.2f\n",
               account.getInterestAmount(),account.getTotalBalance());
   }//end of main method
} //end of the class

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Sample Output:

Interest rate: 5.00 %
Interest amount: 50.00 Total Balance: 1050.00
Interest rate: 10.00 %
Interest amount: 105.00 Total Balance: 1155.00
Interest rate: 10.00 %
Interest amount: 200.00 Total Balance: 2200.00