Java开发网 - 求助：java 语法问题

Topic: 求助：java 语法问题

1.求助：java 语法问题

Posted by: jayinseu
Posted on: 2004-09-19 20:50

ShoppingCartItem scitem = (ShoppingCartItem) items.get(bookId);
(ShoppingCartItem) 是什么意思？编译总是通不过
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package mypack;

import java.util.*;

public class ShoppingCart {
HashMap items = null;
int numberOfItems = 0;

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

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

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

public synchronized int getNumberOfItems() {
return numberOfItems;
}
public synchronized 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 synchronized void clear() {
items.clear();
numberOfItems = 0;
}
}

2.Re:求助：java 语法问题 [Re: jayinseu]	Copy to clipboard
Posted by: lfrick Posted on: 2004-09-19 21:40 那是强制转型的意思；编译不了是因为没有导入“ShoppingCartItem”这个类

3.Re:求助：java 语法问题 [Re: jayinseu]	Copy to clipboard
Posted by: xiaoyu216 Posted on: 2004-09-24 14:24 import java.util.*; 看你的这个路径下有没有ShoppingCartItem这个类，如果没有的话，要用import导入

4.Re:求助：java 语法问题 [Re: jayinseu]	Copy to clipboard
Posted by: scottding Posted on: 2004-09-29 09:39 ShoppingCartItem 这个类一定是你自己定义的类了，java.util.*里面都是JDK系统的类，你的这个类不应该在这下面，看看这个类应该是你自己实现的，确认一下在哪个路径下，导入进来。