      1  /**

      2     A savings account earns interest on the minimum balance.

      3  */

      4  public class SavingsAccount extends BankAccount

      5  {

      6     private double interestRate;

      7     private double minBalance;

      8

      9     /**

     10        Constructs a savings account with a zero balance.

     11     */

     12     public SavingsAccount()

     13     {

     14        interestRate = 0;

     15        minBalance = 0;

     16     }

     17

     18     /**

     19        Sets the interest rate for this account.

     20        @param rate the monthly interest rate in percent

     21     */

     22     public void setInterestRate(double rate)

     23     {

     24        interestRate = rate;

     25     }

     26

     27     public void withdraw(double amount)

     28     {

     29        super.withdraw(amount);

     30        double balance = getBalance();

     31        if (balance < minBalance)

     32        {

     33           minBalance = balance;

     34        }

     35     }

     36

     37     public void monthEnd()

     38     {

     39        double interest = minBalance * interestRate / 100;

     40        deposit(interest);

     41        minBalance = getBalance();

     42     }

     43  }