Question

This is a Java project. It has alot of details T.T The project only uses the CONSOLE! I am looking for many ways to solve this project so if you have the time, please try it! It means so much!!

This is a store management system. It has 3 classes. (Goods, Management, UI) 
There should be an array in the Management class contains Goods objects, and there should be a function that manages this array, meaning adding and deleting objects, while giving the product their IDs.
A Goods object should have the following data memebers and functions.
: categoryName (for example, the category might be 'drinks' and the product name could be lemonade, cola, sprite etc.), name, price, stock, id (which is the product number, the index number of the product)
:addStock, removeStock, and the get/set functions

(There should be a 'totalSales' variable to keep up with the total of the store's sales, but I couldn't decide where to put it.)

In the UI, the first screen should say
1. user
2. manager
3. end
----------
enter number of task: 

When you enter 1, this is a customer buying products. First ask the user which product they want to buy, and how many. (Ask and receive input about the category->product->number) Then you tell the user how much each product costs and how much the total is. If the user agrees to buy the products, the stock should go down and the total sales should go up. If there is no stock left of the product the user wants to purchase, get the exception and tell the user that there is no stock left. 
There should be a int sellEstimate(int index, int sellCount) function which returns how much it costs to buy 'sellCount' amount of the product named 'index'. There could be an exception made here. 
int sell(int index, int sellCount) is a function which after the user agrees to buy the products, reduces the stock, increases the sales total, and returns the total of the user purchase. There needs to be a excepttion or try catch, in case there is no stock left. 

When you enter 2, the second screen shows
1. insert 
2. output (shows list of the new products inserted)
3. find product
4. delete
5. show category
6. go back
----------
enter number of task:

When you enter 1, you should enter new Goods info. The product number should be automatically given to the product. The product number should be the index number in the Goods list.
When you enter 2, it outputs every item you just registered in the console.
When you enter 3, int findGoodsIndex(String goodsName) in the Management class returns the index number of the perimeter that has to be found. 
When you enter 4, void deleteGoods(int index) deletes the index in the goods array of the product.
When you enter 5, in the Management class, there should be a findGoods(String categoryName) function the returns all the products that are in the category named.
When you enter 6, you go back to the first UI screen.

In all the functions or most of them (I think most of them need it), it sould throw an exception if there is no product that you are looking for, or no catefory, or no stock left.

Yeah three files.. Goods, Management, UI maybe four for the user info

Answer 1

Goods.java :

package store;

public class Goods {
   private String categoryName;
   private String name;
   private double price;
   private int stock;
   private int id;
  
   public Goods(String category,String name){
       this.categoryName = category;
       this.name = name;
       this.price = 0.0;
       this.stock = 0;
       this.id = 0;
   }
   public void addStock(int stock){
       this.stock = this.stock+ stock;
   }
   public double removeStock(int stock){
       this.stock = this.stock - stock;
       return this.stock*price;
   }
   public double getPrice(){
       return price;
   }
   public void setPrice(double price){
       this.price = price;
   }
   public int getStock(){
       return this.stock;
   }
   public int getID(){
       return id;
   }
   public String getCategory(){
       return this.categoryName;
   }
   public String getName(){
       return this.name;
   }
   public void setID(int id){
       this.id = id;
   }

}

Management.java:

package store;

import java.util.ArrayList;

import javax.naming.directory.InvalidAttributesException;

public class Management {
   private ArrayList<Goods> goods;
   private double totalSells;
  
   public Management(){
       goods = new ArrayList<Goods>();
       totalSells = 0;
   }
   public void add(Goods g){
       g.setID(goods.size()+1);
       goods.add(g);
   }
   public void delete(int id){
       goods.remove(id);
   }
   public boolean isCategory(String category) {
       for(int i=0;i<goods.size();i++){
           if(goods.get(i).getCategory().compareTo(category)==0){
               return true;
           }
       }
       return false;
   }
   public int getProductId(String name) {
       for(int i=0;i<goods.size();i++){
           if(goods.get(i).getName().compareTo(name)==0){
               return i;
           }
       }
       return -1;
   }
   public void sell(int id, int number) {
       try {
           if(goods.get(id).getStock()<number){
               throw new InvalidAttributesException("Not enough produt for sell.");
           }
           else{
               totalSells = totalSells + goods.get(id).removeStock(number);  
           }
       } catch (Exception e) {
           System.out.println(e.getMessage());
       }
   }
   public double sellEstimate(int id, int number) {
       return goods.get(id).getPrice()*number;
   }
   public void printItems() {
       for(int i=0;i<goods.size();i++){
           System.out.print("Product ID : ");
           System.out.println(i);
           System.out.print("Product Category : ");
           System.out.println(goods.get(i).getCategory());
           System.out.print("Product Name : ");
           System.out.println(goods.get(i).getName());
           System.out.print("Product Price : ");
           System.out.println(goods.get(i).getPrice());
           System.out.print("Product Quantity : ");
           System.out.println(goods.get(i).getStock());
       }
   }
   public void findGoods(String categoryName) {
       for(int i=0;i<goods.size();i++){
           if(goods.get(i).getCategory().compareTo(categoryName)==0){
               System.out.print("Product Name : ");
               System.out.println(goods.get(i).getName());
               System.out.print("Product Price : ");
               System.out.println(goods.get(i).getPrice());
               System.out.print("Product Quantity : ");
               System.out.println(goods.get(i).getStock());
           }
       }  
   }
}

UI.java:

package store;

import java.util.Scanner;

import javax.naming.directory.InvalidAttributesException;

public class UI {
   public static void main(String[] args){
       Management m = new Management();
       boolean repeat = true;
       while(repeat){
           Scanner in = new Scanner(System.in);
           int input = 0;
           double cost = 0.0;
           int amt = 0;
           try{
               System.out.println("Select from menu:");
                System.out.println("1. user");
                System.out.println("2. manager");
                System.out.println("3. end");
                input = in.nextInt();
                if(input>3 || input<1){
                   throw new InvalidAttributesException("Invalid input.");
                }
            }
            catch(Exception e){
               System.out.println(e.getMessage());
            }
            switch (input) {
           case 1:
               System.out.println("Which product they want to buy?");
               System.out.println("Enter Category : ");
               String category = in.next();
               if(!m.isCategory(category)){
                   System.out.println("No such Category! ");
                   break;
               };
               System.out.println("Enter product Name : ");
               String name = in.next();
               int id = m.getProductId(name);
               if(id == -1){
                   break;
               }
               System.out.println("How many you want to buy? ");
               int number = in.nextInt();
               cost = m.sellEstimate(id,number);
               System.out.print("Total amount to be paid : ");
               System.out.println(cost);
               if(cost == -1){
                   break;
               }
               else{
                   m.sell(id,number);
               }
               break;
           case 2:
               try{
                    System.out.println("Select from menu:");
                   System.out.println("1. insert");
                   System.out.println("2. output (shows list of the new products inserted)");
                   System.out.println("3. find product");
                   System.out.println("4. delete");
                   System.out.println("5. show category");
                   System.out.println("6. go back");
                   input = in.nextInt();
                    if(input>6 || input<1){
                       throw new InvalidAttributesException("Invalid input.");
                    }
                }
                catch(Exception e){
                   System.out.println(e.getMessage());
                }
               switch (input) {
               case 1:
                   System.out.println("Enter new product Category : ");
                   String category1 = in.next();
                   System.out.println("Enter product name : ");
                   String name1 = in.next();
                   Goods g = new Goods(category1, name1);
                   System.out.println("Set price of product : ");
                   cost = in.nextDouble();
                   g.setPrice(cost);
                   System.out.println("Enter product quantity : ");
                   amt = in.nextInt();
                   g.addStock(amt);
                   m.add(g);
                   break;
               case 2:
                   m.printItems();
                   break;
               case 3:
                   System.out.println("Enter product name : ");
                   String name2 = in.next();
                   System.out.print("Product ID is : ");
                   System.out.println(m.getProductId(name2));
                   break;
               case 4:
                   System.out.println("Enter product id to Delete : ");
                   int id1 = in.nextInt();
                   m.delete(id1);              
                   break;
               case 5:
                   System.out.println("Enter product Category : ");
                   String categoryName = in.next();
                   m.findGoods(categoryName);
                   break;
               case 6:
                   break;
               default:
                   break;
               }
               break;
           case 3:
               repeat = false;
               break;
           default:
               break;
           }
       }
   }
}