系统概述
查看商品信息
新增商品信息
删除商品信息
卖出商品
商品销售排行榜
步骤1：初始化
package edu.xcdq;

/**

• @qvthor chenjinxing

• @date 2021/4/6 18:43
  /
  public class Article {
  // 名字 单价 库存 已卖数量
  public String name; //商品名字
  public double price; //商品单价
  public int amount; //商品库存数量
  public int number; //商品销售数量
  /*

• 商品信息展示
  */
  public void print( int index ) {
  System.out.println(index +"\t" + name + "\t" + price
  + "\t" + amount + "\t" + number );

  }

  public void setArticle(String mingzi , double danjia , int kucun , int yishou){
  name = mingzi;
  price = danjia;
  amount = kucun;
  number = yishou;
  }

}

商品集合类
package edu.xcdq;

/**

• @qvthor chenjinxing
• @date 2021/4/6 18:46
  */
  public class ArticleSet {
  Article[] articles = new Article [30];
  }

商品管理类
/**

• @qvthor chenjinxing
• @date 2021/4/6 18:44
  */
  public class ArticleManage {
  //创建一个库存，并且初始化

ArticleSet articleSet = new ArticleSet();

// 仓库初始化，放入一些商品
public void initial(){
    Article xiaomi11 = new Article();
    /*xiaomi11.name  = "小米11";
    xiaomi11.number = 30;
    xiaomi11.amount = 0;
    xiaomi11.price = 1999;*/
    xiaomi11.setArticle("小米11",1999,30,0);

    Article xiaomi11Pro = new Article();
    xiaomi11Pro.setArticle("小米11pro",2999,10,0);

    Article xiaomiUltra = new Article();
    xiaomiUltra.setArticle("小米至尊版",3999,20,0);

    articleSet.articles[0] = xiaomi11;
    articleSet.articles[1] = xiaomi11Pro;
    articleSet.articles[2] = xiaomiUltra;

}

步骤2：实现菜单转换
// 启动菜单
public void startMenu() {
boolean flag = true;
do {
System.out.println("**************************");
System.out.println("1 查看商品信息");
System.out.println("2 新增商品信息");
System.out.println("3 删除商品信息");
System.out.println("4 卖出商品");
System.out.println("5 商品销售排行榜");
System.out.println("6 退出");
System.out.println("**************************");

        System.out.println("请输入功能编号");
        Scanner scanner = new Scanner(System.in);
        int funNo =  scanner.nextInt();
        switch (funNo) {
            case 1:
                System.out.println("查看商品信息");
                chakan();
                break;
            case 2:
                System.out.println("2 新增商品信息");
                add();
                break;
            case 3:
                System.out.println("3 删除商品信息");
                dele();
                break;
            case 4:
                System.out.println("卖出商品");
                sell();

                break;
            case 5:
                System.out.println("排行榜");
                leaderboard();
                break;
            case 6:
                System.out.println("谢谢，已退出");
                flag = false;
                break;
            default:
                System.out.println("你输入的功能编号有误");
                break;
        }
    }while ( flag );
}

测试类
package edu.xcdq;

public class Main {
public static void main(String[] args) {
ArticleManage articleManage = new ArticleManage();
articleManage.initial();
articleManage.startMenu();

}

}

步骤3：实现查看商品信息

    /**
     * 查看商品信息
     */
    public void chakan(){
        System.out.println("编号 \t 名字 \t 单价 \t 库存 \t 已售");
        for (int i =0 ; i < articleSet.articles.length ; i++ ) {
            if ( articleSet.articles[i] != null ) {
                //articleSet.articles[i].print(i);
            }
        }

}

步骤4：实现新增商品信息

/**
 * 添加商品信息
 */
private void add() {
    Scanner scanner = new Scanner(System.in);
    System.out.println("请输入商品的名称：");
    String name = scanner.next();
    System.out.println("请输入单价：");
    double price = scanner.nextDouble();
    System.out.println("请输入库存：");
    int count = scanner.nextInt();
    System.out.println("请输入已卖的数量：");
    int number  = scanner.nextInt();

    Article newArticle = new Article();
    newArticle.setArticle(name , price ,count , number );

    for ( int i = 0 ; i < articleSet.articles.length ; i++ ) {
        if ( articleSet.articles[i] == null ) {
            articleSet.articles[i] = newArticle; //把新建的对象放在数组中的第一个空位置
            break; // 后续的空位置直接跳过
        }
    }

}

}

步骤5：实现删除商品信息
/**
* 删除商品信息
*/
private void dele(){
System.out.println("请输入你要删除的商品编号");
Scanner scanner = new Scanner(System.in);
int delNo = scanner.nextInt();
boolean falg = true ;
for (int i = 0 ; i < articleSet.articles.length ; i++){
if (delNo==(i+1) &&articleSet.articles[i]!=null){
int j= i; //备注下标
while (article