librarybook.java

国外的数据结构与算法分析用书

package library;

import dslib.base.CursorUos;

/**	A Book with additional instance variables onLoanTo, dueDate, and isOverdue. 
	It has methods to handle the borrowing and returning events. It also has a 
	position variable to record its position in an onLoan or overdue list. */
public class LibraryBook extends Book implements Comparable
{
	/**	Constructor for the class.
		Analysis : Time = O(1) */
	public LibraryBook(String newTitle, String newAuthor, String newIsbn)
	{
		super(newTitle, newAuthor, newIsbn);
	}

	/**	Is current book less than `other'?.
		Analysis: Time = O(1) */
	public int compareTo(Object other)
	{
		return isbn.compareTo(((LibraryBook)other).isbn);
	}

	/**	The patron who borrowed the book. */
	protected Patron onLoanTo;

	/**	Is the book on loan?
		Analysis: Time = O(1) */
	public boolean isOnLoan()
	{
		return onLoanTo != null;
	}

	/**	An integer to represent the date when the book is due. */
	protected int dueDate;

	/**	Is the book already overdue? */
	public boolean isOverdue;

	/**	Process the borrowing of the book by patron `p' on date `d'. 
		Analysis: Time = O(1) */
	public void borrowed(Patron p, int d)
	{
		onLoanTo = p;
		dueDate = d;
		isOverdue = false;
	}

	/**	String representation of the book information suitable for printing.
		Analysis: Time = O(1) */
	public String toString()
	{
		String result = super.toString();
		if (isOnLoan())
		{
			result += "  On loan to " + onLoanTo.name + " Due back " + dueDate;
			if (isOverdue)
				result += " already overdue.";
		}
		return result;
	}

	/**	Process the returning of the book.
		Analysis: Time = O(1) */
	public void returned()
	{
		onLoanTo = null;
		dueDate = 0;
		isOverdue = false;
		position = null;
	}

	/**	Position of the book in either an onLoan list or the overdue list. */
	protected CursorUos position;

	/**	Set the position to be x.
		Analysis: Time = O(1) */
	public void setPosition(CursorUos x)
	{
		position = x;
	}

	/**	Record the fact that the book is overdue.
		Analysis: Time = O(1) */
	public void setOverdue()
	{
		isOverdue = true;
	}
}