Java Arraylist two different columns

Question

I have an array list with the name and cost of an item, however, I'd like to separate the two, especially so that I can sum the values of the costs.

heres what I have so far:

import java.util.ArrayList;

public class henrys {

    public static ArrayList<String> products = new ArrayList<String>();

    public static void main(String[] args) {
        products.add("Calvin Klein Blue Shorts, Size: Medium, $45");
        products.add("Ralph Lauren Blue Shirt, Size: Large, $50");
        products.add("Gap Beige Khakis, Size: 30, $20");
        products.add("Calvin Klein Black Shirt, Size: Medium, $35");
        products.add("USA Jersey White, Size: Medium, $100");
        System.out.println((products)); 
    }
}

@Bharath Or a [`LinkedHashMap`](http://docs.oracle.com/javase/7/docs/api/java/util/LinkedHashMap.html). — Elliott Frisch, Jun 30 '14 at 01:53
Don't represent a Product as a string; create a Product class with all of the various properties you need, with the appropriate types. — Jacob Mattison, Jun 30 '14 at 01:53
@ElliottFrisch yes he wants to maintain the order, he could use LinkedHashMap. — Bharath, Jun 30 '14 at 01:56

Joseph Boyle · Answer 1 · 2014-07-03T03:57:50.437

3

Creating an ArrayList like this really doesn't make sense, and goes completely against the purpose of a language centered around objects.

Create a Product class, give it a name, price, and size field, and then create an ArrayList of Product objects.

To get the sum of the prices, you could iterate over every Product in the ArrayList and add its price:

Sidenote: Storing monetary values as a double is horrible idea. I only did it to show you how to get started.

FINAL EDIT

You need to create a class called Product with the following code:

public class Product {

    public String name, size;
    public double price;

    public Product(String name, String size, double price){
        this.name = name;
        this.size = size;
        this.price = price;
    }

}

In your Main Class:

public static void main(String[] args){
    ArrayList<Product> products = new ArrayList<Product>();
    products.add(new Product("Shorts", "Small", 5.45);
    products.add(new Product("Shirt", "Large", 15.15);
    products.add(new Product("Hat", "Small", 10.25);

    //Calculate total price.
    double price = 0.00;
    for(Product p : products){
        price += p.price;
    }
    System.out.println("Total cost: " + price);

}

edited Jul 03 '14 at 03:57

answered Jun 30 '14 at 02:01

Joseph Boyle

560
5
15

in that way would it be easy to sum the prices? – user3788811 Jun 30 '14 at 03:21
@JoeBoyle how would I add an object if I used this format? – user3788811 Jun 30 '14 at 23:21
Why "Storing monetary values as a double is horrible idea" ? – Ismail Yavuz Jul 02 '14 at 17:02
1

@ismailyavuz Double and Float datatypes are floating point. Floating point values encounter "round-off" errors. For example, doing 1.03 - .42 would return 0.6100000000000001. For more on why we don't use floating point datatypes for currency, see http://stackoverflow.com/questions/3730019/why-not-use-double-or-float-to-represent-currency – Joseph Boyle Jul 02 '14 at 17:07
i inputted this and when I play it I get no result – user3788811 Jul 03 '14 at 03:48
@user3788811 I'd need to see your code. Any errors? – Joseph Boyle Jul 03 '14 at 03:51
@user3788811 I'll create a final edit with all of the code in one place. – Joseph Boyle Jul 03 '14 at 03:54
@user3788811 I have made a final edit. If you need further help with basic OOP principles, I'd suggest Google'ing some Java tutorials. – Joseph Boyle Jul 03 '14 at 03:58

Java Arraylist two different columns

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