java中map使用例子与代码。为一个购物车的列子

import java.util.*;
import java.io.*;

public class ShoppingCart implements Serializable
{
/**
*
*/
private static final long serialVersionUID = 1L;

Map<String,Integer> items = new HashMap<String,Integer>();
int numberOfItems = 0;

public synchronized void add(String itemName)
{
if(items.containsKey(itemName))
{
Integer itemCount = (Integer)items.get(itemName);
items.put(itemName, new Integer(itemCount + 1));
}
else
{
items.put(itemName,new Integer(1));
}

numberOfItems ++;
}

public synchronized int getNumberOfItems()
{
return numberOfItems;
}

public synchronized Map<String,Integer> getItems()
{
return items;
}
}

－－－－－－－－－－－－－－－使用
        Map<String,Integer> items = cart.getItems();
Iterator<Map.Entry<String,Integer>> itor = items.entrySet().iterator();
while(itor.hasNext())
{
Map.Entry<String, Integer> entry = itor.next();

out.println(entry.getKey() + “:” + entry.getValue() + “<br>”);

}

http://blog.163.com/lieight@126/blog/static/6664927520137792529940/