shoppingcart.java

初期JAVA学习非常有用的资料。帮助深入了解API。特别是Applet。

/*
 * Copyright (c) 1998 Sun Microsystems, Inc. All Rights Reserved.
 *
 * This software is the confidential and proprietary information of Sun
 * Microsystems, Inc. ("Confidential Information").  You shall not
 * disclose such Confidential Information and shall use it only in
 * accordance with the terms of the license agreement you entered into
 * with Sun.
 *
 * SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF THE
 * SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 * PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR ANY DAMAGES
 * SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING
 * THIS SOFTWARE OR ITS DERIVATIVES.
 *
 * CopyrightVersion 1.0
 */

package cart;

import java.util.*;
import database.BookDetails;
 
public class ShoppingCart {
    HashMap items = null;
    int numberOfItems = 0;

    public ShoppingCart() {
        items = new HashMap();
    }

    public void add(String bookId, BookDetails book) {
        if(items.containsKey(bookId)) {
            ShoppingCartItem scitem = (ShoppingCartItem) items.get(bookId);
            scitem.incrementQuantity();
        } else {
            ShoppingCartItem newItem = new ShoppingCartItem(book);
            items.put(bookId, newItem);
        }

        numberOfItems++;
    }

    public void remove(String bookId) {
        if(items.containsKey(bookId)) {
            ShoppingCartItem scitem = (ShoppingCartItem) items.get(bookId);
            scitem.decrementQuantity();

            if(scitem.getQuantity() <= 0)
                items.remove(bookId);

            numberOfItems--;
        }
    }

    public Collection getItems() {
        return items.values();
    }

    protected void finalize() throws Throwable {
        items.clear();
    }

    public int getNumberOfItems() {
        return numberOfItems;
    }
    public double getTotal() {
        double amount = 0.0;

        for(Iterator i = getItems().iterator(); i.hasNext(); ) {
            ShoppingCartItem item = (ShoppingCartItem) i.next();
            BookDetails bookDetails = (BookDetails) item.getItem();

            amount += item.getQuantity() * bookDetails.getPrice();
        }
        return roundOff(amount);
    }

    private double roundOff(double x) {
        long val = Math.round(x*100); // cents
        return val/100.0;
    }

    public void clear() {
        items.clear();
        numberOfItems = 0;
    }
}