包含的功能

增加商品

private static void addItem(ArrayList<Item> shoppingCartList, Scanner sc) {
        String id = null;
        while(true){
            System.out.println("请输入商品编号");
            id = sc.next();
            //判断购物车是否有这个物品编号，如果有返回索引，没有返回-1
            int index = isExSitingId(shoppingCartList, id);
            if(index == -1){
                break;
            }else{
                System.out.println("您输入的商品编号已经存在！");
            }
        }
        System.out.println("请输入商品的名字：");
        String name = sc.next();
        System.out.println("请输入商品的描述：");
        String desc = sc.next();
        System.out.println("请输入商品的价格：");
        double price = sc.nextDouble();
        System.out.println("请输入商品的购买数量：");
        int count = sc.nextInt();

		//每次添加一个物品，都要new一个新的Item
        Item item = new Item(id, name, desc, price, count);
        shoppingCartList.add(item);
        System.out.println("添加成功");
    }

删除商品

private static void deleteItemByItemId(ArrayList<Item> shoppingCartList,Scanner sc) {
        if(shoppingCartList.isEmpty()){
            System.out.println("购物车空空如也");
            return;
        }
        String id = "";
        //判断有没有这个商品id
        System.out.println("请输入你要删除的商品编号：");
        id = sc.next();
        int index = isExSitingId(shoppingCartList, id);
        if (index == -1) {
            System.out.println("您输入的商品编号不存在，请确认后，重新选择操作！");
            return;
        } else {
            shoppingCartList.remove(index);
            System.out.println("删除成功");
        }

    }

修改商品购买数量

private static void updateItemByItemId(ArrayList<Item> shoppingCartList, Scanner sc) {
        if(shoppingCartList.isEmpty()){
            System.out.println("购物车空空如也");
            return;
        }
        System.out.println("请输入你要修改的商品编号：");
        String updateId = sc.next();
        int index = isExSitingId(shoppingCartList,updateId);
        if(index == -1){
            System.out.println("您输入的商品编号不存在，请确认后，重新选择操作！");
            return;
        }else {
            while (true) {
                System.out.println("请输入你要购买的商品数量：");
                int newCount = sc.nextInt();
                if(newCount>0){
                    Item item = shoppingCartList.get(index);
                    item.setCount(newCount);
                    System.out.println("修改成功");
                    showItem(shoppingCartList);
                    break;
                }else{
                    System.out.println("商品购买的数量必须大于0");
                }
            }
        }
    }

展示商品

private static void showItem(ArrayList<Item> shoppingCartList) {
        if(shoppingCartList.isEmpty()){
            System.out.println("购物车空空如也");
            return;
        }
        System.out.println("商品编号\t\t商品名字\t\t商品描述\t\t商品价格\t\t商品购买数量");
        for (int i = 0; i < shoppingCartList.size(); i++) {
            Item item = shoppingCartList.get(i);
            System.out.println(item.getId()+"\t\t\t"+item.getName()+"\t\t\t"+item.getDesc()+"\t\t\t"
            +item.getPrice()+"\t\t\t"+item.getCount());
        }

    }

源代码

Item.java

package com.Junswl.shopping;

public class Item {
	//商品编号
    private String id;
    //商品名称
    private String name;
    //商品描述
    private String desc;
    //商品价格
    private double price;
    //购买的商品数量
    private int count;
	
	//空参
    public Item() {
    }
	
	//满参
    public Item(String id, String name, String desc, double price, int count) {
        this.id = id;
        this.name = name;
        this.desc = desc;
        this.price = price;
        this.count = count;
    }

	//get and set 方法
    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDesc() {
        return desc;
    }

    public void setDesc(String desc) {
        this.desc = desc;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        this.count = count;
    }
}

ShoppingCart.java

package com.Junswl.shopping;

import java.awt.*;
import java.util.ArrayList;
import java.util.Scanner;

public class ShoppingCart {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        ArrayList<Item> shoppingCartList = new ArrayList<>();
        while (true){
            Menu();
            System.out.println("请输入你的选择");
            int num = sc.nextInt();
            switch(num){
                case 1:
                    addItem(shoppingCartList,sc);
                    break;
                case 2:
                    deleteItemByItemId(shoppingCartList,sc);
                    break;
                case 3:
                    updateItemByItemId(shoppingCartList,sc);
                    break;
                case 4:
                    showItem(shoppingCartList);
                    break;
                default:
                    System.out.println("选择错误，请重新选择");
            }
        }
    }

    private static void updateItemByItemId(ArrayList<Item> shoppingCartList, Scanner sc) {
        if(shoppingCartList.isEmpty()){
            System.out.println("购物车空空如也");
            return;
        }
        System.out.println("请输入你要修改的商品编号：");
        String updateId = sc.next();
        int index = isExSitingId(shoppingCartList,updateId);
        if(index == -1){
            System.out.println("您输入的商品编号不存在，请确认后，重新选择操作！");
            return;
        }else {
            while (true) {
                System.out.println("请输入你要购买的商品数量：");
                int newCount = sc.nextInt();
                if(newCount>0){
                    Item item = shoppingCartList.get(index);
                    item.setCount(newCount);
                    System.out.println("修改成功");
                    showItem(shoppingCartList);
                    break;
                }else{
                    System.out.println("商品购买的数量必须大于0");
                }
            }
        }
    }

    private static void deleteItemByItemId(ArrayList<Item> shoppingCartList,Scanner sc) {
        if(shoppingCartList.isEmpty()){
            System.out.println("购物车空空如也");
            return;
        }
        String id = "";
        //判断有没有这个商品id
        System.out.println("请输入你要删除的商品编号：");
        id = sc.next();
        int index = isExSitingId(shoppingCartList, id);
        if (index == -1) {
            System.out.println("您输入的商品编号不存在，请确认后，重新选择操作！");
            return;
        } else {
            shoppingCartList.remove(index);
            System.out.println("删除成功");
        }

    }

    private static void showItem(ArrayList<Item> shoppingCartList) {
        if(shoppingCartList.isEmpty()){
            System.out.println("购物车空空如也");
            return;
        }
        System.out.println("商品编号\t\t商品名字\t\t商品描述\t\t商品价格\t\t商品购买数量");
        for (int i = 0; i < shoppingCartList.size(); i++) {
            Item item = shoppingCartList.get(i);
            System.out.println(item.getId()+"\t\t\t"+item.getName()+"\t\t\t"+item.getDesc()+"\t\t\t"
            +item.getPrice()+"\t\t\t"+item.getCount());
        }

    }

    private static void addItem(ArrayList<Item> shoppingCartList, Scanner sc) {
        String id = null;
        while(true){
            System.out.println("请输入商品编号");
            id = sc.next();
            int index = isExSitingId(shoppingCartList, id);
            if(index == -1){
                break;
            }else{
                System.out.println("您输入的商品编号已经存在！");
            }
        }
        System.out.println("请输入商品的名字：");
        String name = sc.next();
        System.out.println("请输入商品的描述：");
        String desc = sc.next();
        System.out.println("请输入商品的价格：");
        double price = sc.nextDouble();
        System.out.println("请输入商品的购买数量：");
        int count = sc.nextInt();

        Item item = new Item(id, name, desc, price, count);
        shoppingCartList.add(item);
        System.out.println("添加成功");
    }

    //判断商品id是否存在
    private static int isExSitingId(ArrayList<Item> shoppingCartList,String id){
        for (int i = 0; i < shoppingCartList.size(); i++) {
            Item item = shoppingCartList.get(i);
            if(item.getId().equals(id)){
                return i;
            }
        }
        return -1;
    }

    public static void Menu(){
        System.out.println("================购物车=============");
        System.out.println("1.添加商品到购物车");
        System.out.println("2.删除购物车商品");
        System.out.println("3.修改商品数量");
        System.out.println("4.查询购物车");
    }
}

学的不是技术，更是梦想！！！