Java基础语法之购物车Demo

1. 需求

实现购物车的商品添加、修改、查询等功能
能够与用户交互

2. 学习目标

学习数组
学习面向对象编程思想，类的定义以及使用
学习if else switch while 分支语句

2. 实现

创建商品类
Goods.java

package demo;

/**
 * @title 商品类
 * @description 商品类
 * */
public class Goods {
	public int id;
	public String name;
	public double price;
	public int number;
}

创建公共打印函数，主要是为了打印商品信息
Common.java

package utils;
import demo.Goods;

public class Common {
	/**
	 * @Title 遍历数组
	 * @Description
	 * @param int
	 * @return void
	 */
	public void printArray(int[] array) {
		for (int i=0;i<array.length;i++) {
			System.out.print(array[i] + ";");
		}
		System.out.println();
	}
	
	public void printShop(Goods[] ga) {
		System.out.println("您购买的商品如下：");
		System.out.println("编号\t\t名称\t\t价格\t\t购买数量");
		for (int i=0;i<ga.length;i++) {
			if(ga[i] == null) {
				break;
			}
			System.out.println(ga[i].id + "\t\t;" + ga[i].name+"\t\t;" + ga[i].price+"\t\t;" + ga[i].number);
		}
		System.out.println();
	}
}

创建主函数 ShopMain.java

package demo;
import java.util.Scanner;

import utils.Common;

public class ShopMain {
	public static void main(String[] args) {
		//1.定义一个商品类
		//2.定义一个数组
		Goods[] shopCar = new Goods[100];
		//3.搭建操作架构
		OUT:
		while(true) {
			System.out.println("########欢迎光临#########");
			System.out.println("添加商品：1");
			System.out.println("查询商品：2");
			System.out.println("修改商品：3");
			System.out.println("结算购买：4");
			System.out.println("退出：0");
			System.out.println("请选择命令操作");
			System.out.println("########欢迎光临#########");
			Scanner sc = new Scanner(System.in);
			int userInput = sc.nextInt();
			switch(userInput) {
				case 1:
					addGoods(shopCar, sc);
					break;
				case 2:
					queryGoods(shopCar);
					break;
				case 3:
					updateGoods(shopCar, sc);
					break;
				case 4:
					pay(shopCar);
					break;
				case 0:
					System.out.println("欢迎下次光临");
					break OUT;
				default:
					System.out.println("命令错误");
				
			}
		}
		
	}
	/**
	 * @title 支付订单
	 * */
	private static void pay(Goods[] shopCar) {
		// TODO Auto-generated method stub
		double sum = 0;
		for(int i = 0; i < shopCar.length; i++) {
			if(shopCar[i] != null) {
				sum += shopCar[i].price * shopCar[i].number;
			}
		}
		System.out.println("总共："+sum+"￥");
		
	}
	/**
	 * @title 查询商品
	 * */
	private static void queryGoods(Goods[] shopCar) {
		// TODO Auto-generated method stub
		Common com = new Common();
		com.printShop(shopCar);

	}

	/**
	 * @title 修改商品数量
	 * */
	private static void updateGoods(Goods[] shopCar, Scanner sc) {
		// TODO Auto-generated method stub
		System.out.println("输入商品的id:");
		int id = sc.nextInt();
		for(int i=0; i < shopCar.length; i++) {
			if(shopCar[i] != null && id==shopCar[i].id) {
				System.out.println("找到商品：" + shopCar[i].name);
				System.out.println("输入新的数量");
				int number = sc.nextInt();
				shopCar[i].number = number;
				System.out.println("修改完成！！");
				break;
			}
		}
	}

	/**
	 * @title 增加商品
	 * */
	private static void addGoods(Goods[] shopCar, Scanner sc) {
		// TODO Auto-generated method stub
		System.out.println("请输入商品的编号");
		int id = sc.nextInt();
		System.out.println("请输入商品的名称");
		String name = sc.next();
		System.out.println("请输入商品的价格");
		double price = sc.nextDouble();
		System.out.println("请输入购买的数量");
		int number = sc.nextInt();
		Goods goods = new Goods();
		goods.id = id;
		goods.name = name;
		goods.price = price;
		goods.number = number;
		for(int i=0; i < shopCar.length; i++) {
			if(shopCar[i] == null) {
				shopCar[i] = goods;
				System.out.println("商品：" + name+"添加成功");
				return;
			}
		}
		
	}
}