java的模擬購物車代碼，用hasmap代表購物車存盤商品編號和購買數量，這個購買數量該怎樣存進去？為啥我明明添加了數量，運行出的商品數量為null？還有顯示購物車中商品資訊怎么寫
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public class shangpin {
int bianhao;
String name;
int shuliang;
double danjia;
public shangpin(int bianhao,String name,int shuliang,double danjia) {
super();
this.bianhao = bianhao;
this.name = name;
this.shuliang = shuliang;
this.danjia = danjia;
}
public int getbianhao() {
return bianhao;
}
public void setBianhao(int bianhao) {
this.bianhao = bianhao;
}
public String getname() {
return name;
}
public void setname(String name) {
this.name = name;
}
public int getShuliang() {
return shuliang;
}
public void setShuliang(int shuliang) {
this.shuliang = shuliang;
}
public double getDanjia() {
return danjia;
}
public void setDanjia(double danjia) {
this.danjia = danjia;
}
}
package practise;
import java.nio.channels.Pipe;
import java.security.PrivateKey;
import java.util.*;
import java.util.Scanner;
import java.util.concurrent.ConcurrentHashMap.KeySetView;
public class gouwuche {
public static void main(String[] args) {
int bh=0;int sl;int t=0;
System.out.println("**********購物車***********");
System.out.println("1，加入購物車");
System.out.println("2，修改購買數量");
System.out.println("3，洗掉");
System.out.println("4，退出");
while(t!=4)
{
System.out.println("請輸入選項1~4");
Scanner sc=new Scanner(System.in);
t=sc.nextInt();
switch (t) {
case 1:
{xssp();
System.out.print("請輸入商品編號:");
Scanner sc1 =new Scanner(System.in);
bh = sc1.nextInt();
System.out.print("請輸入商品數量:");
sl = sc1.nextInt();
tjgwc(bh,sl);
xsgwc(bh);
} break;
case 2:
{
xsgwc(bh);
System.out.print("請輸入要修改的編號:");
Scanner sc2=new Scanner(System.in);
int m = sc2.nextInt();
if(m>0&&m<=bh) {
System.out.print("請輸入數量:");
int n= sc.nextInt();
xgsl(m,n);
xsgwc(bh);
}
else System.out.print("編號錯誤！");
} break;
case 3:
{
xsgwc(bh);
System.out.print("請輸入要洗掉的商品編號:");
Scanner sc1=new Scanner(System.in);
int m = sc1.nextInt();
scsp(m,bh);
xsgwc(bh);
}break;
case 4:System.out.print("退出");break;
default:System.out.print("輸入錯誤，請重新輸入：");break;
}
}
}
private static void xssp(){
shangpin p1=new shangpin(1,"牙膏",2,2.0);
shangpin p2=new shangpin(2,"牙刷",2,4.0);
shangpin p3=new shangpin(3,"毛巾",6,5.0);
shangpin p4=new shangpin(4,"水杯",3,10.0);
ArrayList list=new ArrayList();
list.add(p1);
list.add(p2);
list.add(p3);
list.add(p4);
System.out.print("編號:"+p1.bianhao+" 名稱:"+p1.name+" 數量:"+p1.shuliang+" 單價:"+p1.danjia+"\n");
System.out.print("編號:"+p2.bianhao+" 名稱:"+p2.name+" 數量:"+p2.shuliang+" 單價:"+p2.danjia+"\n");
System.out.print("編號:"+p3.bianhao+" 名稱:"+p3.name+" 數量:"+p3.shuliang+" 單價:"+p3.danjia+"\n");
System.out.print("編號:"+p4.bianhao+" 名稱:"+p4.name+" 數量:"+p4.shuliang+" 單價:"+p4.danjia+"\n");
}
private static void xsgwc(int bh) {
ArrayList list=new ArrayList();
Map map=new HashMap();
if(map != null)
System.out.println("商品編號："+bh+"商品數量:"+map.get(bh));
else System.out.print("購物車為空！！");
}
private static void tjgwc(int bh,int sl) {
Map<String, Integer> map=new HashMap();
map.put("bh", sl);
}
private static void xgsl(int m,int n) {
Map map=new HashMap();
map.put("m", n);
}
private static void scsp(int x,int bh) {
Map map=new HashMap();
for(int i=1;i<=bh;i++)
if(x==bh) {map.remove(x);break;}
}
}
不好意思啦有點長
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標籤：Eclipse