使用Iterator遍历hashMap

package com.ls.service;

import java.util.*;
import com.ls.domain.Book;
import com.sun.media.sound.AlawCodec;
public class MyCartService {
    
    HashMap<String,Book> hm=new HashMap<String, Book>();
    //Add2 books
    
    public void addBook(String id){
        if(hm.containsKey(id)){
        Book book =hm.get(id);
        int shoppingNum=book.getShoppingNum();
        book.setShoppingNum(shoppingNum+1);
        }else{
        hm.put(id, new BookService().getBookById(id));
        }
    }
    
    
    
    //Add books
    public void addBook(String id,Book book){
        if(hm.containsKey(id)){
        System.out.println("hm.containsKey(id)");
        int shoppingNum=book.getShoppingNum();
        book.setShoppingNum(shoppingNum+1);
        }else{
            System.out.println("xxx");
            hm.put(id, book);    
        }
    }
    
    
    
    //Delete books
    public void deleteBook(String id){
        hm.remove(id);
    }
    
    
    
    
    //Update books/myCart   numbers
    
    public void updateBook(String id,String num){
        //取出ID对应book
        Book book =hm.get(id);
        book.setShoppingNum(Integer.parseInt(num));
        
    }
    
    
    //显示购物车中的所有商品信息
    public ArrayList showMyCart(){
        
                  ArrayList<Book> alBook=new ArrayList<Book>();
        
    //遍历hashMap
    
        
    Iterator iterator =hm.keySet().iterator();
    while(iterator.hasNext()){
    //key
    String id=(String)iterator.next();
    //Book
    Book book=hm.get(id);
    alBook.add(book);
        }
        return alBook;
    }
    
    //返回该购物车的总价
    public float getToatlPrice(){
        float totalPrice=0.0f;
        
        //得到总价格
        ArrayList<Book> al =new ArrayList<Book>();
        
        Iterator iterator=hm.keySet().iterator();
        while(iterator.hasNext()){
            //取出书号
            
            String bookId=(String)iterator.next();
            //取出书号对应的bookbean
            Book book=hm.get(bookId);
    totalPrice+=book.getPrice()*book.getShoppingNum();
            
        }
        
        
        return totalPrice;
    }
    
    //Clear books/myCart
    public void cleanBook(){
        hm.clear();
    }
    

}