1  // A subclass of the savings account class.
  2  // This example illustrates adding instance variables and
  3  // overriding a method in the parent class.
  4  //       Nancy McCracken  3/14/97
  5  
  6  
  7  public class AccountCmp extends Account
  8  { 
  9    // instance variables 
 10    //  also inherits name, balance, interestrate
 11    static double minbalance = 6000.;
 12    static double penalty = 20.;
 13  
 14    // constructor method is same as parent
 15    public AccountCmp (String n, double b)
 16    { super (n, b);  }
 17  
 18    // override one method
 19    //  also inherits getname, getbalance, getbalancedollars, getbalancecents
 20    //                 withdraw, and deposit
 21    public double monthactivity()
 22    { if (balance < minbalance) balance -= penalty;
 23      double newbalance = balance * 
 24                       (double)(Math.pow (1 + (interestrate/12)/30, 30));
 25      double interest = newbalance - balance;
 26      balance = newbalance;
 27      return interest;
 28    }
 29  }
 30