Account.java

package org.prevayler.demos.demo2.business;

import java.util.*;

public class Account implements java.io.Serializable {

	private static final long serialVersionUID = 3998522662411373397L;
	private long number;
	private String holder;
	private long balance = 0;
	private List transactionHistory = new ArrayList();
	private transient Set listeners;
    
    private Account() {
    }
    
	Account(long number, String holder) throws InvalidHolder {
		this.number = number;
		holder(holder);
	}
    
	public long number() {
		return number;
	}

	public String toString() { //Returns something like "00123 - John Smith"
		return numberString() + " - " + holder;
	}

	public String numberString() {
		return numberString(number);
	}
	
	static String numberString(long number) {
		return (new java.text.DecimalFormat("00000").format(number));
	}

	public String holder() {
		return holder;
	}

	public void holder(String holder) throws InvalidHolder {
		verify(holder);
		this.holder = holder;
		notifyListeners();
	}
    
	public long balance() {
		return balance;
	}

	public void deposit(long amount, Date timestamp) throws InvalidAmount {
		verify(amount);
        register(amount, timestamp);
	}

	public void withdraw(long amount, Date timestamp) throws InvalidAmount {
		verify(amount);
        register(-amount, timestamp);
	}

    private void register(long amount, Date timestamp) {
		balance += amount;
        transactionHistory.add(new AccountEntry(amount, timestamp));
		notifyListeners();
	}
    
	private void verify(long amount) throws InvalidAmount {
		if (amount <= 0) throw new InvalidAmount("Amount must be greater than zero.");
		if (amount > 10000) throw new InvalidAmount("Amount maximum (10000) exceeded.");
	}

    public List transactionHistory() {
        return transactionHistory;
    }

	public void addAccountListener(AccountListener listener) {
		listeners().add(listener);
	}

	public void removeAccountListener(AccountListener listener) {
		listeners().remove(listener);
	}
	
	private Set listeners() {
		if (listeners == null) listeners = new HashSet();
		return listeners;
	}
	
	private void notifyListeners() {
		Iterator it = listeners().iterator();
		while (it.hasNext()) {
			((AccountListener)it.next()).accountChanged();
		}
	}

	public class InvalidAmount extends Exception {
		private static final long serialVersionUID = 3343517565045905857L;

		InvalidAmount(String message) {
			super(message);
		}
	}

	private void verify(String holder) throws InvalidHolder {
		if (holder == null || holder.equals("")) throw new InvalidHolder();
	}

	public class InvalidHolder extends Exception {
		private static final long serialVersionUID = -3234126892127577122L;

		InvalidHolder() {
			super("Invalid holder name.");
		}
	}
}