Question

Can you please rewrite this Java code so it can be better understood.

import java.util.HashMap;
import java.util.Scanner;
import java.util.Map.Entry;

public class Shopping_cart {
  
   static Scanner s= new Scanner (System.in);
  
//   declare hashmap in which key is dates as per mentioned and Values class as value which consists all the record of cases
   static HashMap<String,Item> map= new HashMap<>();

   public static void main(String[] args) {
       // TODO Auto-generated method stub
       getupdates();
   }
  
   static void getupdates() {
      
       System.out.println("Welcome to Shopping Cart. Enter:");
       System.out.println("1 : Add an Item ");
       System.out.println("2 : Add multiples Quantities of Given Item ");
       System.out.println("3 : Remove an unspecified Item ");
       System.out.println("4 : CheckOut");
       System.out.println("5 : Checkbudget");
       System.out.print("Choice: ");
       int selection= s.nextInt();
      
      
       switch(selection) {
       case 1:
          add_new_item();
          getupdates();
            
          case 2:
              Add_multiples_items();
              getupdates();
                
          case 3:
              remove_unspecified_data();
              getupdates();
                
          case 4:
                  checkout();
                  getupdates();
                 
          case 5:
                
              checkbudget();
              getupdates();
                    
          case 6:
              System.out.println("Stay Safe");
              break;
                
              default:
                  System.out.println("Invalid choice");
                   System.out.println("Please enter the valid choice");
                   getupdates();
                    
       }
   }

   public static int total_price() {
      
       int total_price=0;
       for (Entry<String, Item> entry : map.entrySet()) {
                  
                   Item it=map.get(entry.getKey());
                  
                   total_price+=it.getPrice()*it.get_quantity();
                  
               }
         
       return total_price;
      
   }
  
  
     
  
   private static void checkbudget() {
      
       System.out.print("Enter your Total Budget : ");
       int budget=s.nextInt();
      
       int totalprice=0;
  

System.out.println("Total Amount = "+total_price());

while(budget<total_price()) {
   totalprice = remove_unspecified_data();
     
     
     
   if(budget>=totalprice) {
       break;
   }
}

System.out.println();

System.out.println("Now updates cart : ");

checkout();

System.out.println();
      
   }

   private static void checkout() {
       System.out.println(" Here list of Items in Your Cart");
      
       int i=1;
       int total_price=0;
       System.out.println(" S.no Name of item Quantity price ");
       System.out.println(" ");
       for (Entry<String, Item> entry : map.entrySet()) {
          
           Item it=map.get(entry.getKey());
          
           System.out.println(" "+i+" "+entry.getKey()+" "+it.get_quantity()+" $"+it.getPrice()*it.get_quantity());
           total_price+=it.getPrice()*it.get_quantity();
           i++;
       }
      
       System.out.println();
      
       System.out.println("Total Amount = "+total_price);
      
       System.out.println();
       System.out.println();
   }

   private static int remove_unspecified_data() {
      
       System.out.print("Enter the item you want to remove from your cart : ");
       String name=s.next();
      
       Item it1=map.get(name);
      
       int quant=it1.get_quantity();
      
       if(quant>1) {
          
       quant--;
       it1.set_quantity(-1);
      
       map.put(name, it1);
       }
         
       else {
           map.remove(name, it1);
       }
      
       int total_price=total_price();
         
       total_price-=it1.getPrice();
         
       System.out.println();
       System.out.println();
      
       return total_price;
      
   }

   private static void Add_multiples_items() {
       System.out.print("Enter the item you want to add in your cart : ");
       String name=s.next();
      
System.out.println("Enter price of Item : ");
      
       int price=s.nextInt();
      
       System.out.print("Enter the quantity of that item you want to add : ");
       int quan=s.nextInt();
      
       if(map.containsKey(name)) {
           Item it1=map.get(name);
           it1.set_quantity(quan);
           map.put(name, it1);
       }
       else {
           Item it= new Item(name,price,quan);
           map.put(name, it);
       }
      
       System.out.println();
       System.out.println();
      
   }

   private static void add_new_item() {
       System.out.print("Enter the item you want to add in your cart : ");
      
       String name=s.next();
      
       System.out.println("Enter price of Item : ");
      
       int price=s.nextInt();
      
      
      
       if(map.containsKey(name)) {
           Item it1=map.get(name);
           it1.set_quantity(1);
           map.put(name, it1);
       }
       else {
           Item it= new Item(name,price,1);
           map.put(name, it);
       }
      
       System.out.println();
       System.out.println();
      
   }
  
  

}

class Item
{   
private String name;
private int price;
private int quantity; //in cents
  
//Constructor
public Item(String n, int p,int quantity)
{
name = n;
price = p;
this. quantity=quantity;
}
  
public boolean equals(Item other)
{
return this.name.equals(other.name) && this.price == other.price;
}
  
//displays name of item and price in properly formatted manner
public String toString()
{
return name + ", price: $" + price/100 + "." + price%100;
}
  
//Getter methods
public int getPrice()
{
return price;
}
  
public int get_quantity()
{
return quantity;
}
  
public void set_quantity(int qa)
{
   quantity+=qa;
}
  
public String getName()
{
return name;
}
}

Answer 1

Hope these comments will help you understand the code better.

import java.util.HashMap;
import java.util.Scanner;
import java.util.Map.Entry;

public class Shopping_cart {

    static Scanner s= new Scanner (System.in);

    //   declare hashmap in which key is dates as per mentioned and Values class as value which consists all the record of cases
    // map here will function as the cart. An item added will be included in the map and will be accessed through the map only
    // map functions as a cart for the program
    static HashMap<String,Item> map= new HashMap<>();

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        getupdates();
    }

    static void getupdates() {

        System.out.println("Welcome to Shopping Cart. Enter:");
        System.out.println("1 : Add an Item ");
        System.out.println("2 : Add multiples Quantities of Given Item ");
        System.out.println("3 : Remove an unspecified Item ");
        System.out.println("4 : CheckOut");
        System.out.println("5 : Checkbudget");
        System.out.print("Choice: ");
        int selection= s.nextInt();
        
        // After taking input, switch() will pick up the case corresponding to the number you have entered
        switch(selection) {
            case 1:
                add_new_item();
                getupdates();
                break;

            case 2:
                Add_multiples_items();
                getupdates();
                break;

            case 3:
                remove_unspecified_data();
                getupdates();
                break;

            case 4:
                checkout();
                getupdates();
                break;

            case 5:

                checkbudget();
                getupdates();
                break;

            case 6:
                System.out.println("Stay Safe");
                break;

            default:
                System.out.println("Invalid choice");
                System.out.println("Please enter the valid choice");
                getupdates();

        }
    }

    // returns the total price in the cart
    public static int total_price() {

        int total_price=0;
        //for each entry in the map, iterate over the map and add the price in the total price 
        for (Entry<String, Item> entry : map.entrySet()) {

            Item it=map.get(entry.getKey());

            total_price+=it.getPrice()*it.get_quantity();

        }

        return total_price;

    }




    /*
    * This function checks the your budget and if it is less than the final price of checkout, then it wil ask
    * you to remove certain items from the cart
    * */
    private static void checkbudget() {

        System.out.print("Enter your Total Budget : ");
        int budget=s.nextInt();

        int totalprice=0;



        System.out.println("Total Amount = "+total_price());

        //if budget is less than total price in cart, then remove the items from the cart
        while(budget<total_price()) {
            totalprice = remove_unspecified_data();
            
            if(budget>=totalprice) {
                break;
            }
        }


        System.out.println();

        System.out.println("Now updates cart : ");

        checkout();

        System.out.println();

    }

    // prints the details of all the items in the map and return the total price of checkout
    private static void checkout() {
        System.out.println(" Here list of Items in Your Cart");

        int i=1;
        int total_price=0;
        System.out.println(" S.no Name of item Quantity price ");
        System.out.println(" ");
        // iterate over the map and print details of each item
        for (Entry<String, Item> entry : map.entrySet()) {

            Item it=map.get(entry.getKey());

            System.out.println(" "+i+" "+entry.getKey()+" "+it.get_quantity()+" $"+it.getPrice()*it.get_quantity());
            total_price+=it.getPrice()*it.get_quantity();
            i++;
        }

        System.out.println();

        System.out.println("Total Amount = "+total_price);

        System.out.println();
        System.out.println();
    }

    //removes 1 quantity of item from the cart. If there is only 1 quantity available then it removes the complete item from list
    // and returns the total price available in the cart
    private static int remove_unspecified_data() {

        System.out.print("Enter the item you want to remove from your cart : ");
        String name=s.next();

        Item it1=map.get(name);

        int quant=it1.get_quantity();

        // if quantity of item to be removed is more than 1 just decrease its quantity
        if(quant>1) {

            quant--;
            it1.set_quantity(-1);

            map.put(name, it1);
        }

        // if the quantity is 1, remove the item from the map
        else {
            map.remove(name, it1);
        }

        // get the new total price after updation
        int total_price=total_price();

        total_price-=it1.getPrice();

        System.out.println();
        System.out.println();

        return total_price;

    }

    //this function adds item with more than 1 quantity
    private static void Add_multiples_items() {
        System.out.print("Enter the item you want to add in your cart : ");
        String name=s.next();

        System.out.println("Enter price of Item : ");

        int price=s.nextInt();

        System.out.print("Enter the quantity of that item you want to add : ");
        int quan=s.nextInt();

        // if the item is already available in map, then just update its quantity and put back in map
        if(map.containsKey(name)) {
            Item it1=map.get(name);
            it1.set_quantity(quan);
            map.put(name, it1);
        }
        //if item is not in the map then create the instance of item and add it in the map
        else {
            Item it= new Item(name,price,quan);
            map.put(name, it);
        }

        System.out.println();
        System.out.println();

    }

    //this function adds only single quantity item
    private static void add_new_item() {
        System.out.print("Enter the item you want to add in your cart : ");

        String name=s.next();

        System.out.println("Enter price of Item : ");

        int price=s.nextInt();

        // if the item is already available in map, then just update its quantity and put back in map
        if(map.containsKey(name)) {
            Item it1=map.get(name);
            it1.set_quantity(1);
            map.put(name, it1);
        } //if item is not in the map then create the instance of item and add it in the map
        else {
            Item it= new Item(name,price,1);
            map.put(name, it);
        }

        System.out.println();
        System.out.println();

    }



}

/*
* This class is the structure defination of how the item structure will look. It contains name (the name of item), price (price
* of the item) and quantity (its quantity).
* @equal(Item other) : returns if one Item is equal to another
* @toString() : return the parameters of class Item in string format.
* */
class Item
{
    private String name;
    private int price;
    private int quantity; //in cents

    //Constructor
    public Item(String n, int p,int quantity)
    {
        name = n;
        price = p;
        this. quantity=quantity;
    }

    public boolean equals(Item other)
    {
        return this.name.equals(other.name) && this.price == other.price;
    }

    //displays name of item and price in properly formatted manner
    public String toString()
    {
        return name + ", price: $" + price/100 + "." + price%100;
    }

    //Getter methods
    public int getPrice()
    {
        return price;
    }

    public int get_quantity()
    {
        return quantity;
    }

    public void set_quantity(int qa)
    {
        quantity+=qa;
    }

    public String getName()
    {
        return name;
    }
}