代码如下:
第一种方法: 用重载 参数传递方式;
import java.util.Scanner;
class shangchang1
{
	public static void main(String[] args) 
	{
		menu();
	}
	public static void show(){
		System.out.println("--------------------库存管理-----------------------");
		System.out.println("1.查看库存清单");
		System.out.println("2.修改商品库存数量");
		System.out.println("3.退出");
	}
	public static void menu(){
		System.out.println("品牌型号"+"\t"+"尺寸"+"\t"+"价格"+"\t"+"库存数");
		String[] model={"MacBookAir","ThinkpadT450","ASUS-FL5800"};
		double[] size={13.3,14.0,15.6};
		double[] money={6988.88,5999.99,4999.5};
		int[] count={5,10,18};
Scanner sc=new Scanner(System.in);
		while(true){
			show();
			int choose=sc.nextInt();
		  switch (choose){
		case 1 :show1(model,size,money,count);
			break;
		case 2:dapte(model,size,money,count);
			break;
		case 3:
			return;
		default:
			System.out.println("您输入有误,请重新输入");
break;
		}
		}
	}
	public static void show1(String[] model,double[] size,double[] money,int[] count){
System.out.println("品牌型号"+"\t"+"尺寸"+"\t"+"价格"+"\t"+"库存数");
				for(int i=0;i<size.length;i++){
System.out.println(model[i]+"\t"+size[i]+"\t"+money[i]+"\t"+count[i]);
				}
System.out.println("--------------------------------------------------");
int sum=0;
for(int i=0;i<count.length;i++){
sum+=count[i];
}
System.out.println("总库存数:"+sum);
				double sum1=0;
				for(int i=0;i<count.length;i++){
sum1=count[i]*money[i]+sum1;
				}
System.out.println("库存商品总金额:"+sum1);
	}
	public static void dapte(String[] model,double[] size,double[] money,int[] count){
		//展示商品信息
			System.out.println("品牌型号"+"\t"+"尺寸"+"\t"+"价格"+"\t"+"库存数");
				for(int i=0;i<size.length;i++){
System.out.println((i+1)+"\t"+model[i]+"\t"+size[i]+"\t"+money[i]+"\t"+count[i]);   //增加编号
				}
				System.out.println("请输入你要修改的商品序号: ");
				Scanner sc=new Scanner(System.in);
				int choose=sc.nextInt();
				System.out.println("请输入你要修改的库存数量: ");
				int number=sc.nextInt();
				//修改库存
				count[choose-1]=number;  
	}
}
第二种方法:用ArrayList方法;
创建一个类名;
class goods
{
  String brand;
  double size;
  double price;
  int num;
}
代码:
import java.util .Scanner;
import java.util .ArrayList;
public class shangchang2 {
   public static void main(String[] args) 
	{
	   menu();
	}
   public static void show(){
		System.out.println("--------------------库存管理-----------------------");
		System.out.println("1.查看库存清单");
		System.out.println("2.修改商品库存数量");
		System.out.println("3.退出");
	 }
	public static void menu(){                    
		goods g1=new goods();                                      //创建3个对象;
		g1 .brand="MacBookAir";
g1.size=13.3;
		g1.price=6988.88;
		g1.num=5;
    goods g2=new goods();
		g2 .brand="ThinkpadT450";
g2.size=14.0;
		g2.price=5999.99;
		g2.num=10;
		goods g3=new goods();
		g3 .brand="ThinkpadT450";
g3.size=14.0;
		g3.price=5999.99;
		g3.num=18;
		ArrayList<goods> arr=new ArrayList<goods>();
		arr.add(g1);
		arr.add(g2);
		arr.add(g3);
Scanner sc=new Scanner(System.in);
		while(true){
			show();
			int choose=sc.nextInt();
		  switch (choose){
		case 1 :show(arr);
			break;
		case 2:dapte(arr);
			break;
		case 3:
			return;
		default:
			System.out.println("您输入有误,请重新输入");
break;
		}
		}
	}
	public static void show(ArrayList<goods> arr){
	  System.out.println("品牌型号"+"\t"+"尺寸"+"\t"+"价格"+"\t"+"库存数");
	  for (int i=0;i<arr.size();i++ ){
			System.out.println(arr.get(i).brand+"\t"+arr.get(i).size+"\t"+arr.get(i).price+"\t"+arr.get(i).num);
	  }
	}
	public static void dapte(ArrayList<goods> arr){
		//展示商品信息
			System.out.println("品牌型号"+"\t"+"尺寸"+"\t"+"价格"+"\t"+"库存数");
				for(int i=0;i<arr.size();i++){
System.out.println((i+1)+"\t"+arr.get(i).brand+"\t"+arr.get(i).size+"\t"+arr.get(i).price+"\t"+arr.get(i).num);   //增加编号
				}
				System.out.println("请输入你要修改的商品序号: ");
				Scanner sc=new Scanner(System.in);
				int choose=sc.nextInt();
				if(choose<arr.size()){
System.out.println("请输入你要修改的商品序号: ");
Scanner sc=new Scanner(System.in);
int choose=sc.nextInt();
//System.out.println("您输入商品序号不存在,请重新输入 ");
				}
				System.out.println("请输入你要修改的库存数量: ");
				int number=sc.nextInt();
				//修改库存
				arr.get(choose-1).num=number;
	}
}
二种效果如下:

