10.14

通过java基础的相关知识，设计并完成一个简单的商品录入系统，可以实现：菜单显示、商品信息展示、商品信息录入、商品信息查询、退出的功能

package cn.cxy.exec;

import java.util.Scanner;

public class Product {
//成员变量
static String[] names = {"iPhoneXS","华为 Mate 20 pro","小米X","vivo NEX","oppo Find"};
static double[] price = {8999,5399,2399,4399,3999};
static int[] numbers = {50,20,80,120,90};

public static void main(String[] args) {
/*
* ----------------------
* 1. 商品列表
* 2. 商品录入
* 3. 商品查询
* 4. 统计信息
* 5. 退出
* ----------------------
* 选择：> 1
* ....
*/

//死循环显示菜单
outer:
while(true) {
//显示菜单，并获得选择的值
int c = menu();
//判断c的值
switch(c) {
case 1: f1(); break;
case 2: f2(); break;
case 3: f3(); break;
case 4: f4(); break;
case 5: break outer;
}
}
}

private static int menu() {
System.out.println("----------------------");
System.out.println("1. 商品列表");
System.out.println("2. 商品录入");
System.out.println("3. 商品查询");
System.out.println("4. 统计信息");
System.out.println("5. 退出");
System.out.println("----------------------");
System.out.print("选择：> ");
return new Scanner(System.in).nextInt();
}

private static void f1() {
/*
names
["A", "B", "C"]
price
[2, 8, 3]
numbers
[200, 300, 180]
0 1 2
1. 名称：xx，价格：xx，数量：xx
*/
for(int i=0;i<names.length;i++) {
String n = names[i];
double p = price[i];
int b = numbers[i];
System.out.println(
(i+1)+". 名称："+n+"，价格："+p+"，数量："+b);
}
}

private static void f2() {
/*
names
["A", "B", "C"]
price
[2, 8, 3]
numbers
[200, 300, 180]
0 1 2
*/
//遍历数组
for (int i = 0; i < names.length; i++) {
System.out.println("录入第"+(i+1)+"件商品：");
System.out.print("名称：");
String n = new Scanner(System.in).nextLine();
System.out.print("价格：");
double p = new Scanner(System.in).nextDouble();
System.out.print("数量：");
int b = new Scanner(System.in).nextInt();
names[i] = n;
price[i] = p;
numbers[i] = b;
}
//重新显示商品列表
f1();
}

private static void f3() {
/*
names
["A", "B", "C"]
price
[2, 8, 3]
numbers
[200, 300, 180]
0 1 2
字符串，比价是否相等，要用equals()方法
a = "aaa"
b = "aaa"
a.equals(b)
*/
System.out.print("输入查询的商品名：");
String n = new Scanner(System.in).nextLine();
//遍历数组
for (int i = 0; i < names.length; i++) {
// n 和 names[i] 相等
if(n.equals(names[i])) {
String name = names[i];
double p = price[i];
int b = numbers[i];
System.out.println(
(i+1)+". 名称："+name+"，价格："+p+"，数量："+b);
return;
}
}
//循环结束，所有商品都比较完，没有找到
System.out.println("找不到商品");
}

private static void f4() {
/*
names
["A", "B", "C"]
price
[2, 8, 3]
numbers
[200, 300, 180]
0 1 2
*/
//商品总价，单价均价，最高单价，最高总价
double spzj = 0;//商品总价
double djzj = 0;//单价总价
double zgdj = 0;//最高单价
double zgzj = 0;//最高总价
//遍历数组
for (int i = 0; i < names.length; i++) {
spzj += price[i] * numbers[i];
djzj += price[i];
//数组中，找到更大的值
if(price[i] > zgdj) {
zgdj = price[i];//更大值存到这个变量
}
if(price[i]*numbers[i] > zgzj) {
zgzj = price[i]*numbers[i];
}
}
System.out.println("商品总价："+spzj);
System.out.println("单价均价："+(djzj/names.length));
System.out.println("最高单价："+zgdj);
System.out.println("最高总价："+zgzj);
}
}