import java.util.ArrayList;

public class Account {
	
	// The current balance in the account.
	private int balance = 1000;  // Protected by lock on "this"
	
	private ArrayList<AccountListener> listeners = new ArrayList<AccountListener>();
	
	/**
	 * Withdraw money from the account.  This method is synchronized so that only one 
	 * thread at a time can access the account balance.
	 * @param amount the amount to withdraw.
	 */
	public synchronized void withdraw (int amount) {
		//balance = balance - amount;
		int newBalance = balance - amount;
		Thread.yield();
		balance = newBalance;
		notifyListeners();
	}
	
	/**
	 * Deposit money into the account.  This method is synchronized so that only one 
	 * thread at a time can access the account balance.
	 * @param amount the amount to deposit.
	 */
	public synchronized void deposit (int amount) {
		//balance = balance + amount;
		int newBalance = balance + amount;
		Thread.yield();
		balance = newBalance;
		notifyListeners();
	}

	/**
	 * Returns the account balance.  This method is synchronized to guarantee that 
	 * the balance is read from memory, not from a cache on a multiprocessor.
	 * @return the account balance
	 */
	public synchronized int getBalance() {
		// TODO Auto-generated method stub
		return balance;
	}

	/**
	 * @param bank
	 */
	public void addListener(AccountListener bank) {
		listeners.add(bank);
	}
	
	public void notifyListeners() {
		for (int i = 0; i < listeners.size(); i++) {
			listeners.get(i).balanceChanged(balance);
		}
	}
	
}