aspectj program

Question

I am learning aspectj and I have the following program:

import org.aspectj.lang.JoinPoint;

   privileged aspect newaccount
   {
       void around(account a, double x) : execution(void account.withdraw(double)) && target(a) && args(x){
           if(x < 0){
               System.out.println("trying to cheat!");
               return;
           }
           else if(x > a.balance){
               System.out.println("not enough money!");
               return;
           }
           proceed(a, x);
       }
       void around( account a, double x) : execution(void account.deposit(double)) && target(a) && args(x){
           if(x < 0){
               System.out.println("trying to deposit negtive money!");
               return;
           }
           proceed(x);
    }
       after(): execution(public static void *.main(String[])){
           account a3 = new account(3000,"he nerd");
           a3.withdraw(-100);
           a3.deposit(90);
           a3.printbalance();
       }
   }

and I want to protect the account by adding a password as well as adding a charge fee when a withdraw lowers the balance below a certain minimum.

I also want to keep track of all the transactions made on an account.

How could I implement that?

I am compiling this program with an existing java program: 

public class account
{
    private double balance;
    private String owner;
    public account(double x, String s) { balance=x; owner=s; }
    public String owner() { return owner; }
    public void withdraw(double a) { balance -= a; }
    public void deposit(double a) { balance += a; }
    public void printbalance() { System.out.println(balance); }

    // main for testing:
  public static void main(String[] argv)
  {
      account a1 = new account(2000,"you boss");
      account a2 = new account(1000,"me nerd");
      a1.deposit(400);
      a2.withdraw(400);   // not enough money!
      a2.withdraw(300);  // trying to cheat!
      a1.printbalance();
      a2.printbalance();
  }//main
} // account

I would appreciate your help. Thank you.