import java.text.NumberFormat;
public abstract class Account implements Cloneable
{
	//Instance data
	private String number;
	private double balance;
	
	//Constructors		
	public Account(double balance)
	{
		if (balance < 0.0)
			throw new RuntimeException("Initial Balance cannot be negative");
			
		this.number = nextAccountNumber();
		this.balance = balance;
	}

	public Account()
	{
		this(0.0);
	}

	//Accessors	
	public String getNumber()
	{
		return this.number;
	}
	
	public double getBalance()
	{
		return this.balance;
	}

	public abstract void deposit(double amount);
	
	public abstract void withdraw(double amount);
	
	//Mutators
	protected void credit(double amount)
	{
		if (amount < 0.0)
			throw new RuntimeException("CREDIT amount cannot be negative");

		this.balance += amount;
	}
	
	protected void debit(double amount)
	{
		if (amount < 0.0)
			throw new RuntimeException("DEBIT amount cannot be negative");

		this.balance -= amount;
	}
	
	public void transfer(double amount, Account source)
	{
		source.withdraw(amount);
		this.deposit(amount);
	}

	//Over-ride of the toString() method		
	private static NumberFormat fmt = NumberFormat.getCurrencyInstance();
	public String toString()
	{
		return padding(this.getClass().getName(), 15) +
				 " " + this.getNumber() +
				 " Balance: " + fmt.format(this.getBalance());
	}

	private static String padding(String str, int width)
	{
		while (str.length() < width)
			str += " ";
		return str;
	}
	
   public boolean equals(Object other)
   {
      if (other == null)
         return false;
         
      if (other.getClass() != this.getClass())
         return false;
         
      Account that = (Account)other;
      return this.balance == that.balance &&
             this.number.equals(that.number);
   }
   
   public Object clone()
   {
    try
      {
         Account twin = (Account)super.clone();
         return twin;
      }
      catch (CloneNotSupportedException cx)
      {
         return null;
      }
   }
 
      
	//Helpers
	//Automatically create a new account number
	private static int lastNumber = 6000000;
	private static String nextAccountNumber()
	{
		String nbr = "" + (lastNumber++);
		nbr = nbr.substring(0,1) + "-" +
				nbr.substring(1,4) + "-" +
				nbr.substring(4);
		return nbr;
	}
}