add only unique values into the ArrayList

[Sucheta Shrivastava]

Hi, I have made a shopping cart that contains product class, LineItems class and Order class.
I Order class that has addToCart method that adds only the unique products. Like if i add Books and Books item is already present  , then add only the quantity. I have made an attempt but it adds the renewed quantity as
well as the old one.  I even tried using a HashSet still its not working.

Please help.

package com.techlabs.shoppingcart.order;

import java.sql.Date;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;

import com.techlabs.shoppingcart.lineitems.LineItem;

public class Order {

	String id;
	String date;
	OrderStatus status;
	
	 Set<LineItem> newitems= new HashSet<LineItem>();
	List<LineItem> items = new ArrayList<LineItem>();
  
	

	public Order(String id ,String date2, OrderStatus status) {
		this.id=id;
		this.date = date2;
		this.status = status;
	}

	public List<LineItem> getItems() {
		return items;

	}

	public int addToCart(LineItem item) {
		int index=0;
		
		for(LineItem list :items){
		if (list.getName() == item.getName()){
			 index = item.getQuantity()+list.getQuantity();
			
	      list.setQuantity(index);
	    
	      System.out.println("add to cart ="+list.toString()+"\n"+ getItems());
	     
	     		} 
		  
		}
		items.add(item);
		
		
		newitems.addAll( items);
		
		
		return newitems.size();
		}

	
	public double checkOutCost() {
		double totalCheckOutCost=0;
		
		for (LineItem item : newitems) {
			totalCheckOutCost = totalCheckOutCost + item.calculateLineItemCost();
			System.out.print(item.toString());
			System.out.println("\tcost = "+ item.calculateLineItemCost());
		}
       return totalCheckOutCost;
	}

}

Main Class

package com.techlabs.shoppingcart.order;

import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.List;

import com.techlabs.shoppingcart.lineitems.LineItem;
import com.techlabs.shppingcart.product.Product;

public class OrderTest {

	public static void main(String[] args) {
		
		Order order = new Order("222","23-11-1990", OrderStatus.DISPATCHED);
		 List<LineItem> items = new ArrayList<LineItem>();
		
		 Product product = new Product("1","Kellogs", 100,10);
		 Product product1 = new Product("2","Vaseline",250,20);
		 Product product2 = new Product("3","Kellogs", 100,0);
		 LineItem item = new  LineItem(product,10,product.getId());
		
	    	LineItem item1 = new LineItem(product1,20,product1.getId());
	    	
		     LineItem item2= new LineItem(product,20,product.getId());
		 
	  //  	LineItem item2= item;
			items.add(item);
			items.add(item1);
			items.add(item2);
     
			printDetails(item,product);
			printDetails(item1,product1);
			printDetails(item2,product);
			
			
	          
			
			order.addToCart(item2);
			order.addToCart(item1);
			int size = order.addToCart(item);
           System.out.println(size);
          
           double totalcost = order.checkOutCost();
	          System.out.println("Total cost of items = "+totalcost);
         
	}

	
	public static void printDetails(LineItem item,Product product){
		DecimalFormat df = new DecimalFormat("0.00");
		System.out.println("Name = "+product.getName()+" Id ="+product.getId()+" Cost = "
		          +product.getCost() +" Discount= " + df.format( product.getDiscount())+ " Quantity=" + item.getQuantity()+ 
		          "  Item cost after discount = "  +  df.format(item.calculateLineItemCost()));
		System.out.println();
		System.out.println();
		
	}
}

[Norm Radder]

it adds the renewed quantity as well as the old one.

Can you give an example that shows what you mean?
For example I'd expect this:
given an old value = 3
add in a new count = 4
gives a new value = 3+4 = 7

Where in the posted code does it try to add in the new value?

[Sucheta Shrivastava]

@Norm

Here in this method it is adding the new quantified item as well as the old.

	public int addToCart(LineItem item) {
		int index=0;
		
		for(LineItem list :items){
		if (list.getName() == item.getName()){
			 index = item.getQuantity()+list.getQuantity();
			
	      list.setQuantity(index);
	    
	      System.out.println("add to cart ="+list.toString()+"\n"+ getItems());
	     
	      newitems.add(list);
	      System.out.println("add to cart part 2 = " + newitems.toString());
		} 
		  
		}
		items.add(item);
		
		newitems.addAll( items);
		
		return newitems.size();
		}

Output -

size =3
Name =Kellogs Cost =100.0 product id = 1 Quantity = 30 Id  = 1 cost = 2700.0
Name =Kellogs Cost =100.0 product id = 1 Quantity = 10 Id  = 1 cost = 900.0
Name =Vaseline Cost =250.0 product id = 2 Quantity = 20 Id  = 2 cost = 4600.0



for eg. here in this output , i want only kellogs with quantity 30 (since i gave two inputs - with quantity 20 and quantity 10 , so add To Cart method adds the quantity to 30). Here once the kellogs with quantity 30 is added i want to add only quantity 30  Kellogs to it. And not both the values of Kellogs

[Paul Clapham]

    if (list.getName() == item.getName()){

This line... Don't use the == operator to compare the contents of two String objects; it compares whether the two variables refer to the same object. Use the equals() method of the String object instead.