Problems reading data into an array list from a file in Java

Question

So this is my first time posting here. I am trying to read data from a file, create multiple objects from that data, and then place the created objects into an ArrayList. But every time I have tried, I just get multiple copies of the same object, instead of different objects. I am at my wits end.

Anyways, here is the code for the method to read the data in from the file. Thanks in advance for any help!

public void openShop() throws IOException{
    System.out.println("What is the name of the shop?");
    shopName = keyboard.nextLine();
    setShopFile();
    File openShop = new File(shopFile);
    if (openShop.isFile()){
        Scanner shopData = new Scanner(openShop);
            shopName = shopData.nextLine();
            shopOwner = shopData.nextLine();

            while (shopData.hasNextLine()){
                shopItem.setName(shopData.nextLine());
                shopItem.setPrice(Double.parseDouble(shopData.nextLine()));
                shopItem.setVintage(Boolean.parseBoolean(shopData.nextLine()));
                shopItem.setNumberAvailable(Integer.parseInt(shopData.nextLine()));
                shopItem.setSellerName(shopData.nextLine());
                shopInventory.add(shopItem);

            }
            setNumberOfItems();
    }
    else
        System.out.println("That shop does not exist. Please try to open" +
                          "the shop again.");
    isSaved = true;
}

Kakarot · Accepted Answer · 2014-02-23 20:59:16Z

3

inside your while loop you should create a new instance of an object. Else it would only end up making modifications to the exisiting instance.

Correct way :

while (shopData.hasNextLine()){
   shopItem = new ShopItem(); //This will create a new Object of type ShopItem
   shopItem.setName(shopData.nextLine());
   shopItem.setPrice(Double.parseDouble(shopData.nextLine()));
   shopItem.setVintage(Boolean.parseBoolean(shopData.nextLine()));
   shopItem.setNumberAvailable(Integer.parseInt(shopData.nextLine()));
   shopItem.setSellerName(shopData.nextLine());
   shopInventory.add(shopItem);
}

answered Feb 23, 2014 at 20:59

Kakarot

4,2522 gold badges18 silver badges18 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

pauljwilliams · Accepted Answer · 2014-02-23 20:59:04Z

1

I cant see where you're creating the shopItem instance.

But if you're not creating a new ShopItem each time then every time you go around the loop you're just updating the one instance, and then adding it to the shopInventory.

answered Feb 23, 2014 at 20:59

pauljwilliams

19.3k3 gold badges54 silver badges80 bronze badges

Comments

injecteer · Accepted Answer · 2014-02-23 20:59:36Z

1

You fill your ArrayList using the very same object. You should create a new instance of ShopItem:

while (shopData.hasNextLine()){
  ShopItem shopItem = new ShopItem();
  shopItem.setName(shopData.nextLine());
  ...
}

answered Feb 23, 2014 at 20:59

injecteer

20.8k4 gold badges53 silver badges96 bronze badges

Collectives™ on Stack Overflow

Problems reading data into an array list from a file in Java

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related