Question

Exercise 4: Perform the following on the Account class and test it in the AccountArrayTest:  In the AccountArrayTest class, add a static method called getAverageBalance (Account accounts[]) that returns the average balance of all accounts. Use the enhanced for loop.  In the main method get and print the average accounts balance.  Add an instance method called deposit() that takes a double amount as parameter and if it is positive it adds it to the current balance. If the amount is less than or equal to zero it does nothing.  Add a static method called addInterest(Account accounts[]) that calculates the interest for each account in the accounts array (based on the interestRate value), and then deposits it into the relevant account in that array. (Hint: interest = interestRate * balance/100).  Use the above methods to apply the addInterest() for all the accounts in your AccountArrayTest. Print the accountNo and balance after the update.

Answer 1

/****************************************Account.java**********************/

// TODO: Auto-generated Javadoc
/**
* The Class Account.
*/
public class Account {

   /** The owner. */
   private String owner;

   /** The account number. */
   private String accountNumber;

   /** The balance. */
   private double balance;

   /** The interest rate. */
   private double interestRate;

   /**
   * Instantiates a new account.
   *
   * @param owner the owner
   * @param accountNumber the account number
   * @param balance the balance
   */
   public Account(String owner, String accountNumber, double balance) {
       super();
       this.owner = owner;
       this.accountNumber = accountNumber;
       this.balance = balance;
   }

   /**
   * Gets the owner.
   *
   * @return the owner
   */
   public String getOwner() {
       return owner;
   }

   /**
   * Sets the owner.
   *
   * @param owner the new owner
   */
   public void setOwner(String owner) {
       this.owner = owner;
   }

   /**
   * Gets the interest rate.
   *
   * @return the interest rate
   */
   public double getInterestRate() {
       return interestRate;
   }

   /**
   * Sets the interest rate.
   *
   * @param interestRate the new interest rate
   */
   public void setInterestRate(double interestRate) {
       this.interestRate = interestRate;
   }

   /**
   * Gets the account number.
   *
   * @return the account number
   */
   public String getAccountNumber() {
       return accountNumber;
   }

   /**
   * Sets the account number.
   *
   * @param accountNumber the new account number
   */
   public void setAccountNumber(String accountNumber) {
       this.accountNumber = accountNumber;
   }

   /**
   * Gets the balance.
   *
   * @return the balance
   */
   public double getBalance() {
       return balance;
   }

   /**
   * Sets the balance.
   *
   * @param balance the new balance
   */
   public void setBalance(double balance) {
       this.balance = balance;
   }

   /**
   * Deposit.
   *
   * @param amount the amount
   */
   public void deposit(double amount) {

       this.balance += amount;
   }

   /**
   * Withdraw.
   *
   * @param amount the amount
   */
   public void withdraw(double amount) {

       if (balance > amount) {

           this.balance -= amount;
       }
   }

   /**
   * Adds the interest.
   */
   public void addInterest() {

       this.balance += balance * interestRate / 100;
   }

}
/**********************************AccountArrayTest.java**********************/

/**
* The Class AccountArrayTest.
*/
public class AccountArrayTest {

   /**
   * Gets the average balance.
   *
   * @param accounts the accounts
   * @return the average balance
   */
   public static double getAverageBalance(Account[] accounts) {

       double totalBalance = 0;
       for (Account account : accounts) {

           totalBalance += account.getBalance();
       }

       return totalBalance / accounts.length;

   }

   /**
   * Adds the interest.
   *
   * @param accounts the accounts
   */
   public static void addInterest(Account[] accounts) {

       for (Account account : accounts) {

           account.addInterest();
       }
   }

   /**
   * The main method.
   *
   * @param args the arguments
   */
   public static void main(String[] args) {

       Account[] accounts = new Account[3];

       accounts[0] = new Account("Virat", "12478252", 20000);
       accounts[1] = new Account("Kohli", "12478252", 20000);
       accounts[2] = new Account("MS", "12478252", 20000);
       accounts[0].setInterestRate(10);
       accounts[1].setInterestRate(9);
       accounts[2].setInterestRate(12);
       System.out.println("Average Balance: " + getAverageBalance(accounts));

       addInterest(accounts);

       for (Account account : accounts) {

           System.out.println(
                   "Account number: " + account.getAccountNumber() + " has balance: $" + account.getBalance());
       }

   }
}
/*****************************output******************************/

Average Balance: 20000.0
Account number: 12478252 has balance: $22000.0
Account number: 12478252 has balance: $21800.0
Account number: 12478252 has balance: $22400.0

Please let me know if you have any doubt or modify the answer, Thanks :)