How to check if new added item exist in recyclerView?

Question

Actually i'm developing an inventory app where i scan some EAN codes then i insert the quantity of an item and then i add it to an ArrayList in recyclerView.

For now i had no problem as i've made the inventory part where the items had to have different lines for each in recyclerView but now i have to make the order part and here if an item exist yet in ArrayList i have to sum it's quantity and put it to top of recyclerView.

I was trying to make something like a for loop when i'm going to add a new item and check if it's exist in ArrayList, if it's exist i was going to sum that item quantity with old one but the problem was that sometimes the app was going to crash and that the item wasn't going on top of recyclerView.

Do you have any suggestion on how can i do it?

for (ItemModel item : itemModel) {
    if (item.getCodiceArticolo()
            .equals(code.getText()
                        .toString())) {
        item.setQta(String.valueOf(
                Integer.parseInt(item.getQta()) + 1));
    }
}

I was trying to make something like that.

Answer 1

You do not adderror log to your list, so I guess your program crashes because sometimes there is a value that has no quantity (there is no valid number) and therefore can not parse the number, so in this case you just write that there is one item in list that has not been there yet.

for (ItemModel item : itemModel) {
    if (item.getCodiceArticolo()
            .equals(code.getText()
                        .toString())) {
        try {
            item.setQta(String.valueOf(
                    Integer.parseInt(item.getQta()) + 1));
        }
        catch (Exception ex) {
            item.setQta(String.valueOf(1));
        }
    }
}

If this does not help, please attach error log.

Answer 2

Try this code:

ItemModel matchedItem = null;
int matchedItemIndex = -1;
for (ItemModel item : itemModel) {
    if (item.getCodiceArticolo()
            .equals(code.getText()
                        .toString())) {
        item.setQta(String.valueOf(
                Integer.parseInt(item.getQta()) + 1));
        matchedItem = item;
        matchedItemIndex = itemModel.indexOf(item);
        break;
    }
}

if (matchedItemIndex > -1) {
    itemModel.remove(matchedItem);
    itemModel.add(
            0,
            matchedItem);
    notifyItemMoved(index,
                    0);
}

Answer 3

Three days a go i was getting the "ConcurrentModificationException" but now i'm trying another approach inspired by other answers or better the following one:

boolean nuovo = true;
for (ItemModel itemModels : itemModel) {
    if (itemModels.getCodiceArticolo()
                  .equals(code.getText()
                              .toString())) {
        itemModels.setQta(String.valueOf(
                Integer.parseInt(itemModels.getQta()) + 1));
        nuovo = false;
        break;
    }
}

if (nuovo) {
    itemModel.add(new ItemModel(
            code.getText()
                .toString(),
            "1"));
}

And is not crashing anymore and seems to work fine.

Thank's all for suggestions.

UPDATE

THANKS TO kartik malik ANSWER i was able to even "update" my items by adding the last one added on top, as i'm using reverse recyclerView i've done it by this wasy instead of putting the item to position 0

ItemModel matchedItem = null;
int matchedItemIndex = -1;
boolean nuovo = true;
for (ItemModel itemModels : itemModel) {
    if (itemModels.getCodiceArticolo()
                  .equals(code.getText()
                              .toString())) {
        itemModels.setQta(String.valueOf(
                Integer.parseInt(itemModels.getQta()) +
                Integer.parseInt(qta.getText()
                                    .toString())));
        MediaPlayer mpFound = MediaPlayer.create(
                OrdiniActivity.this,
                R.raw.errorsound);
        mpFound.start();
        matchedItem = itemModels;
        matchedItemIndex = itemModel.indexOf(itemModels);
        nuovo = false;
        break;
    }
}

if (matchedItemIndex > -1) {
    itemModel.remove(matchedItem);
    itemModel.add(matchedItem);
}

if (nuovo) {
    itemModel.add(new ItemModel(
            code.getText()
                .toString(),
            qta.getText()
               .toString()));
}

With the boolean i'm checking if the item exist or not and if it doesn't exist i add the item as a new one.

Answer 4

Since the app is crashing, your ArrayList might not have been initialized as suggested in the comments.

For checking if the item exists you can use

if (arraylist_of_items != null && arraylist_of_items.contains(item)) {
  // do your stuff here
}