checkingaccount.java

来自「国外的数据结构与算法分析用书」· Java 代码 · 共 45 行

/**	A bank account class that allows an overdraft up to the credit limit. */
public class CheckingAccount extends RegularAccount
{
	/**	The extent to which the account may be overdrawn. */
	protected float lineOfCredit;

	/**	Initialize the bank account.
		PRECONDITION:
			nameExists: name != null
			nonNegativeAmount: openingAmount >= 0
		POSTCONDITION:
			ownerSet: owner == name
			balanceSet: balance == openingAmount */
	public CheckingAccount(String name, float openingAmount)
	{
		super(name, openingAmount);
	}

	/**	Set the lineOfCredit amount.
		PRECONDITION:
			amountNonNegative: amount >= 0
		POSTCONDITION:
			lineOfCreditSet: lineOfCredit == amount */
	public void setLineOfCredit(float amount)
	{
		lineOfCredit = amount;
	}

	/**	Withdraw amount from account.
		PRECONDITION:
			positiveAmount: amount >= 0
			enoughFunds: amount <= balance + lineOfCredit
		OR
			positiveAmount: amount >= 0
			enoughFunds: amount <= balance
		POSTCONDITION:
			balanceAcceptable: balance >= -lineOfCredit
		AND
			updatedBalance: balance == entry(balance) - amount */
	public void withdraw(float amount)
	{
		balance = balance - amount;
	}
}