import java.awt.event.*;
import java.text.*;
import javax.swing.*;

public class InnerClassTest{  
   public static void main(String[] args){  
      BankAccount account = new BankAccount(10000);
      account.accrueInterest(10);
      while(true){}
   }
}

class BankAccount{  
   public BankAccount(double initialBalance){  
      balance = initialBalance;
   }
   public void accrueInterest(double rate){
      ActionListener adder = new InterestAdder(rate);
      Timer t = new Timer(2000, adder);
      t.start();
   }

   private double balance;
   //////INNER CLASS//////
   private class InterestAdder implements ActionListener{  
      public InterestAdder(double aRate){
         rate = aRate;
      }

      public void actionPerformed(ActionEvent event){  
         double interest = balance * rate / 100;
         balance += interest;
         System.out.println("new balance: " + balance);
      }
      private double rate;
   }
   /////END INNER CLASS//////
}