BankAccount

   import java.lang.*;

   public abstract class BankAccount {
      private double balance, balance2, balance3, deposit, withdraw;

      public BankAccount() {
         balance = 0;
      }
      public BankAccount(double y) {
         balance = y;
      }
      public void setBalance(double x) {
         balance = x;
      }
      public double getBalance() {
         return balance;
      }
      public void deposit(double x) {
         balance = balance + x;
      }
      public void withdraw(double y) {
         if ((balance - y) < 0) {
            throw new RuntimeException("You will overdraw your account");
         }
         else {
            balance = balance - y;
         }
      }
      public String toString() {
         String output;
         output = "The account has a balance of: $" + this.getBalance();
         return output;
      }
      public abstract double monthlyBalance();
      public abstract String toString();
   }