/*
 * T04n01.java -- Demonstration of Composition (more precisely, Adaptation)
 *
 * SavingsAccount is composed of an Account object; that is, it uses
 * an Account object and its associated methods to do the work
 * needed to maintain a SavingsAccount object.
 */

import java.io.*;

class Account 
{
    private int balance;

    public Account () { balance = 1; }   // free money for opening an account!

    public Account (int initialBalance) { balance = initialBalance; }

    public int fetchBalance() { return balance; }

    public void setBalance(int newBalance) { balance = newBalance; }
}

class SavingsAccount
{
    Account foundation;        // Thus, a SavingsAccount object is composed
                               // of an Account object.

    public SavingsAccount () { foundation = new Account(); }

    public SavingsAccount (int startingBalance) {
        foundation = new Account(startingBalance);
    }

    public int getBalance () { return foundation.fetchBalance(); }

    public void setBalance(int newBalance) {
        // foundation.balance = newBalance;   // this had better fail!
        foundation.setBalance(newBalance);
    }
}

public class T04n01
{
    public static void main (String [] args) 
    {
        SavingsAccount nestEgg = new SavingsAccount();

        System.out.println("Your starting balance is $" + nestEgg.getBalance()
                         + ".");
        nestEgg.setBalance(5000);
        System.out.println("Your balance is now $" + nestEgg.getBalance()
                         + ".");
    }
}