booklist.java

使用swing做的熟悉控件使用的DEMO

package book;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Collection;
import java.util.ArrayList;
import userexception.*;

/**
* class BookList
*/
public class BookList {
	private static BookList instance = new BookList();
	private HashSet books = null;
	private int booknum;
	
	//constructor
	private BookList() {
		booknum = 1;
		books = new HashSet();
		try {
			addBook(new Book(booknum++, "Ten Years", "Kit", Book.COMPUTER, 30.00, "China"));
			addBook(new Book(booknum++, "Red And Black", "Unknown", Book.COMPUTER, 30.00, "People"));
			addBook(new Book(booknum++, "C Programming", "Kit", Book.COMPUTER, 30.00, "China"));
			addBook(new Book(booknum++, "Three Pigs", "Tom", Book.NONCOMPUTER, 34.00, "Family"));
		} catch (AddException e) {
			
		}
	
	}

	//static methods to get the instance
	public static BookList getInstance() {
		return instance;
	}	
	
	//get the books
	public HashSet getBooks() {
		return books;
	}	

	//add a book
	public void addBook(Book bk) throws AddException {
		if(! books.add(bk)) throw new AddException();
	}

	//find books 
	public Collection query(String name, String author, int cat, String from) throws BookNotFoundException{
		ArrayList result = new ArrayList();
		Book tmpBook = null;
		Iterator i = books.iterator();
		while (i.hasNext()) {
			tmpBook = (Book)i.next();
			if(!name.equals("")) {
				if(! tmpBook.getName().equals(name)) continue;	
			} 
			if(!author.equals("")) {
				if(! tmpBook.getAuthor().equals(author)) continue;
			}
			if(!(cat < 0)) {
				if(! (tmpBook.getBookType() == cat)) continue;
			}
			if(!from.equals("")) {
				if(! tmpBook.getFrom().equals(from)) continue;
			}
			System.out.println(tmpBook);
			result.add(tmpBook);
		}

		if(result.size() == 0) throw new BookNotFoundException();
		return result;
	}

	//unique search by bookid
	public Book queryById (int bookid) throws BookNotFoundException {
		Iterator i = books.iterator();
		Book temp = null;
		while (i.hasNext()) {
			temp = (Book)i.next();
			if(temp.getBookId() == bookid) {
				break;
			}	
		}
		if(temp == null) throw new BookNotFoundException();
		return temp;
	}
	
	//modify a book
	public void modifyBook(Book bk) throws BookNotFoundException {
		Book old = queryById(bk.getBookId());
		/*	
		if( old != null) {
			books.remove(old);
			books.add(bk);
		}
		*/
		old.setName(bk.getName());
		old.setAuthor(bk.getAuthor());
		old.setBookType(bk.getBookType());
		old.setCost(bk.getCost());
		old.setFrom(bk.getFrom());
		
	}
	
	//make unique number for the new book
	public int makeNo() {
		return booknum++; 
	}
}