account.java

国外的数据结构与算法分析用书

/**	A simple bank account class that is an implementation of the interface AccountADT. */
public class Account implements AccountADT
{
	/**	The name of the owner. */
	private String owner;

	/**	The current balance in the account. */
	private float balance;

	/**	The current line of credit for the account. */
	private float lineOfCredit;

	/**	The name of the owner.
		Analysis: Time = O(1) */
	public String owner()
	{
		return owner;
	}

	/**	The current balance in the account. 
		Analysis: Time = O(1) */
	public float balance()
	{
		return balance;
	}

	/**	The current line of credit for the account.
		Analysis: Time = O(1) */
	public float lineOfCredit()
	{
		return lineOfCredit;
	}

	/**	Create bank account.
		Analysis: Time = O(1)
		PRECONDITION:
			amount >= 0
			openingLoc >= 0 
		POSTCONDITION:
			owner == name
			balance == openingAmount
			lineOfCredit == openingLoc */
	public Account(String name, float openingAmount, float openingLOC)
	{
		owner = name;
		balance = openingAmount;
		lineOfCredit = openingLOC;
	}

	/**	Deposit an amount in the account.
		Analysis: Time = O(1)
		PRECONDITION:
			amount >= 0 
		POSTCONDITION:
			balance() == entry(balance()) + amount
			owner() == entry(owner())
			lineOfCredit() == entry(lineOfCredit()) */
	public void deposit(float amount)
	{
		balance += amount;
	}

	/**	Withdraw an amount from the account.
		Analysis: Time = O(1)
		PRECONDITION:
			amount >= 0 
			amount <= balance() + lineOfCredit()
		POSTCONDITION:
			balance() == entry(balance()) - amount
			owner() == entry(owner())
			lineOfCredit() == entry(lineOfCredit()) */
	public void withdraw(float amount)
	{
		balance -= amount;
	}

	/**	Change approved line of credit for the account.
		Analysis: Time = O(1)
		PRECONDITION:
			amount >= 0 
			balance() >= -amount 
		POSTCONDITION:
			balance() == entry(balance())
			owner() == entry(owner())
			lineOfCredit() == amount */
	public void changeLOC(float amount)
	{
		lineOfCredit = amount;
	}

/** INVARIANT:
	lineOfCredit() >= 0
	balance() >= -lineOfCredit() */
}