添加商品到购物车报错
package com.imooc.goods;
/**
* 商品信息类
* @author ZYH
*
*/
public class Goods {
private String goodsId;// 商品编号
private String goodsName;// 商品名称
private double price;// 商品价格
private String goodsDesp;// 商品描述
// 构造方法
public Goods() {
}
public Goods(String goodsId, String goodsName, double price, String goodsDesp) {
this.setGoodsId(goodsId);
this.setGoodsName(goodsName);
this.setPrice(price);
this.setGoodsDesp(goodsDesp);
}
// get、set方法
public String getGoodsId() {
return goodsId;
}
public void setGoodsId(String goodsId) {
this.goodsId = goodsId;
}
public String getGoodsName() {
return goodsName;
}
public void setGoodsName(String goodsName) {
this.goodsName = goodsName;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public String getGoodsDesp() {
return goodsDesp;
}
public void setGoodsDesp(String goodsDesp) {
this.goodsDesp = goodsDesp;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((goodsDesp == null) ? 0 : goodsDesp.hashCode());
result = prime * result + ((goodsId == null) ? 0 : goodsId.hashCode());
result = prime * result + ((goodsName == null) ? 0 : goodsName.hashCode());
long temp;
temp = Double.doubleToLongBits(price);
result = prime * result + (int) (temp ^ (temp >>> 32));
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj.getClass() == Goods.class) {
Goods goods = (Goods) obj;
return goods.getGoodsId().equals(goodsId) && goods.getGoodsName().equals(goodsName)
&& (goods.getPrice() == price) && goods.getGoodsDesp().equals(goodsDesp);
}
return false;
}
@Override
public String toString() {
return "商品信息[编号：" + this.getGoodsId() + ", 名称：" + this.getGoodsName() + ", 价格：" + this.getPrice() + ", 描述："
+ this.getGoodsDesp() + "]";
}
}
package com.imooc.goods;
/**
* 商品管理类
*/
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
public class GoodsManage {
private Set<Goods> goods;//存放集合
public Set<Goods> getGoods() {
return goods;
}
public void setGoods(Set<Goods> goods) {
this.goods = goods;
}
//构造方法
public GoodsManage() {
}
public GoodsManage(Set<Goods> goods) {
this.setGoods(goods);
}
Set<Goods> set=new HashSet<Goods>();
//商品信息导入
public void importGoods() {
Goods good1=new Goods("goods001","水杯",56,"不锈钢水杯");
Goods good2 = new Goods("goods002", "饮水机", 299, "带净化功能的饮水机");
Goods good3 = new Goods("goods003", "笔记本电脑", 4999, "15寸笔记本电脑");
Goods good4 = new Goods("goods004", "手机", 2300, "android手机");
set.add(good1);
set.add(good2);
set.add(good3);
set.add(good4);
System.out.println("商品信息导入成功 ！");
}
//显示所有商品信息
public void displayAllGoods() {
if(set.size()==0) {
System.out.println("商品为空，请导入");
}else {
Iterator<Goods> it=set.iterator();
while(it.hasNext()) {
System.out.println(it.next());
}
}
}
}
package com.imooc.goods;
/**
* 购物车中的商品信息类
* @author ZYH
*
*/
public class GoodsInCart {
private Goods goods;//商品信息
private int num;//商品数量
//构造方法
public GoodsInCart() {
}
public GoodsInCart(Goods goods,int num) {
this.setGoods(goods);
this.setNum(num);
}
public Goods getGoods() {
return goods;
}
public void setGoods(Goods goods) {
this.goods = goods;
}
public int getNum() {
return num;
}
public void setNum(int num) {
this.num = num;
}
}
package com.imooc.goods;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Scanner;
import java.util.Set;
/**
* 购物车类
*
* @author ZYH
*
*/
public class ShoppingCart {
private Map<String, GoodsInCart> shoppingCart;// Map类购物车
// 构造方法
public ShoppingCart() {
}
public ShoppingCart(Map<String, GoodsInCart> shoppingCart) {
this.setShoppingCart(shoppingCart);
}
public Map<String, GoodsInCart> getShoppingCart() {
return shoppingCart;
}
public void setShoppingCart(Map<String, GoodsInCart> shoppingCart) {
this.shoppingCart = shoppingCart;
}
Map<String, GoodsInCart> shopping = new HashMap<String, GoodsInCart>();
Scanner sc = new Scanner(System.in);
/**
* 添加商品到购物车
*
* @param gm
*/
public void addGoodsToCart(GoodsManage gm) {
Set<Goods> set = gm.getGoods();
boolean flag;
Goods goods;
String str;
if (gm.getGoods().size()==0) {
System.out.println("购物车为空！");
} else {
gm.displayAllGoods();
for (Goods a : set) {
System.out.println("请输入购买的商品编码：");
str =sc.next();
if (a.getGoodsId().equals(str)) {
flag = true;
goods = a;
break;
}
if (flag = true) {
System.out.println("请输入购买数量：");
int n = sc.nextInt();
GoodsInCart go = new GoodsInCart(a, n);
shopping.put(str, go);
} else {
System.out.println("没找到该商品！");
}
}
}
}
/**
* 修改购物车中的商品数量
*/
public void updateNumInCart() {
Set<String> set = shopping.keySet();
String s = null;
int n = 0;
for (String str : set) {
System.out.println("请输入要修改的商品编号：");
s = sc.next();
if (str.equals(s)) {
System.out.println("请输入要修改的数量：");
n = sc.nextInt();
if (n == 0) {
set.remove(str);
System.out.println("因为数量为0，故已移除该商品");
}
shopping.get(str).setNum(n);
}
Set<Entry<String, GoodsInCart>> set1 = shopping.entrySet();
for (Entry<String, GoodsInCart> entry : set1) {
System.out.println(entry.getValue());
}
}
}
/**
* 显示购物车中所有商品
*/
public void displayAllInCart() {
Set<Entry<String, GoodsInCart>> set = shopping.entrySet();
if(set.size()==0) {
System.out.println("购物车空，请补充商品");
}
for (Entry<String, GoodsInCart> entry : set) {
System.out.println(entry.getValue());
}
}
/**
* 结算
*/
public void settleAccounts() {
Set<Entry<String, GoodsInCart>> set = shopping.entrySet();
int sum = 0;
for (Entry<String, GoodsInCart> s : set) {
sum += (s.getValue().getGoods().getPrice() * s.getValue().getNum());
}
System.out.println("总金额为：" + sum);
set.clear();//清空购物车
}
}
package com.imooc.goods;
/**
* 测试类
*/
import java.util.Scanner;
import java.util.Set;
public class TestDemo {
public static void main(String[] args) {
GoodsManage gm = new GoodsManage();
ShoppingCart SC = new ShoppingCart();
Scanner sc = new Scanner(System.in);
boolean flag = true;
int n = 0;
while (flag) {
System.out.println("*********************************");
System.out.println(" 主菜单 ");
System.out.println(" 1-商品管理 ");
System.out.println(" 2-购物车 ");
System.out.println(" 0-退出 ");
System.out.println("*********************************");
n = sc.nextInt();
flag = flag;
if (n < 0 || n > 2) {
System.out.println("输入错误，请重新输入！");
flag = true;
continue;
}else if(n==0) {
System.out.println("***欢迎您下次光临***");
break;
}else {
switch (n) {
case 1:
while (true) {
System.out.println("*********************************");
System.out.println(" 商品管理");
System.out.println(" 1-商品信息导入 ");
System.out.println(" 2-显示所有商品信息 ");
System.out.println(" 9-返回上一级菜单 ");
System.out.println("*********************************");
int i = sc.nextInt();
if (i != 1 && i != 2 && i != 9) {
System.out.println("输入不正确，请重新输入！");
continue;
} else {
switch (i) {
case 1:
gm.importGoods();
break;
case 2:
gm.displayAllGoods();
break;
}
}
if (i == 9) {
flag = true;
break;
}
}
break;
case 2:
while (true) {
System.out.println("*********************************");
System.out.println(" 购物车管理");
System.out.println(" 1-添加商品到购物车");
System.out.println(" 2-修改购物车中的商品数量");
System.out.println(" 3-显示购物车中的所有商品信息");
System.out.println(" 4-结算");
System.out.println(" 9-返回上一级菜单");
System.out.println("*********************************");
int i = sc.nextInt();
if (i < 1 || i > 4 && i!= 9) {
System.out.println("输入不正确，请重新输入！");
continue;
}else {
switch (i) {
case 1:
SC.addGoodsToCart(gm);
break;
case 2:
SC.updateNumInCart();
break;
case 3:
SC.displayAllInCart();
break;
case 4:
SC.settleAccounts();
break;
}
}
if (i == 9) {
flag = true;
break;
}
}break;
}
}
}
}
}93
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2回答
你好，在GoodsManage类中定义了一个private Set<Goods> goods;属性集合，又定义了一个Set<Goods> set=new HashSet<Goods>();集合属性，这两个保留一个就可以了，建议如果保留前者，要写成private Set<Goods> goods=new HashSet<Goods>();来初始化集合。祝学习愉快~
THappy
2018-01-26 15:51:22
我这里把你的代码修改后可以正常添加商品到购物车了，下面是修改后的代码和正常添加商品的运行截图，为了方便查看效果，展示购物车中的商品的方法也稍作了修改，建议再仔细对照参考一下~
public void addGoodsToCart(GoodsManage gm) {
if (gm.getGoods().size() == 0) {
System.out.println("未导入商品！");
} else {
gm.displayAllGoods();
Iterator<Goods> it = gm.getGoods().iterator();
System.out.println("请输入购买的商品编码：");
String str = sc.next();
boolean flag = true;
while (it.hasNext()) {
Goods g = it.next();
if (str.equals(g.getGoodsId())) {
flag=true;
System.out.println("请输入要添加的数量");
int num = sc.nextInt();
GoodsInCart goodsInCart = new GoodsInCart(g, num);
shopping.put(str, goodsInCart);
break;
} else {
flag = false;
}
}
if (!flag) {
System.out.println("商品编号不存在");
}
}
}
public void displayAllInCart() {
Set<Entry<String, GoodsInCart>> set = shopping.entrySet();
if (set.size() == 0) {
System.out.println("购物车空，请补充商品");
}
for (Entry<String, GoodsInCart> entry : set) {//此处做了修改，因为需要展示购物车中的每个商品信息
GoodsInCart gic = entry.getValue();
System.out.println(gic.getGoods()+"数量："+gic.getNum());
}
}
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