Java Android Json OutOfMemoryError

Question

I'm trying to decode a json string and do something with the contents. I have this code that runs whenever the user presses a button:

public List<Card> readCards()
{
    List<Card> cards = new ArrayList<Card>();

    HttpReader httpReader = new HttpReader();
    httpReader.setOnResultReadyListener(new HttpReader.OnResultReadyListener() {
        @Override
        public void resultReady(String result) {
            JsonHelper jsonHelper = new JsonHelper();
            List<Card> cards = jsonHelper.getCards(result);

            for (int i = 0; i < cards.size(); i++ ) {
                cards.add(new Card(cards.get(i).getId(), cards.get(i).getNaam(), cards.get(i).getMana(), cards.get(i).getAttack(), cards.get(i).getHealth(), cards.get(i).getEffect(), cards.get(i).getZeldzaamheid(), cards.get(i).getTypeId(), cards.get(i).getSubtypeId(), cards.get(i).getClassId(), cards.get(i).isGoud()));
            }
        }
    });
    httpReader.execute("http://jsonstring.com"); //link to json-file

    return cards;
}

The getCards(result) method from the jsonHelper class is this:

public List<Card> getCards(String jsonText) {
    List<Card> list= new ArrayList<Card>();

    try {
        JSONArray jsonArrayCards = new JSONArray(jsonText);
        for (int i = 0; i < jsonArrayCards.length(); i++) {
            JSONObject jsonObjectCard = jsonArrayCards.getJSONObject(i);    

                Card card = new Card();
                if ( jsonObjectCard.has("id")) { card.setId(jsonObjectCard.getString("id")); } else { card.setId("none"); }
                if ( jsonObjectCard.has("name")) { card.setNaam(jsonObjectCard.getString("name")); } else { card.setNaam("none"); }
                if ( jsonObjectCard.has("cost")) { card.setMana(jsonObjectCard.getInt("cost")); } else { card.setMana(0); }
                if ( jsonObjectCard.has("attack")) { card.setAttack(jsonObjectCard.getInt("attack")); } else { card.setAttack(0); }
                if ( jsonObjectCard.has("health")) { card.setHealth(jsonObjectCard.getInt("health")); } else { card.setHealth(0); }
                if ( jsonObjectCard.has("text")) { card.setEffect(jsonObjectCard.getString("text")); } else { card.setEffect(""); }
                card.setTypeId(1);
                card.setSubtypeId(1);
                card.setClassId(1);
                list.add(card);
        }
    } catch (JSONException e) {
        Log.e("JSON Parser", "Error parsing data " + e.toString());
    }

    return list;
}

After this is done I'm trying to show to the size of the returned list, which is 0 for some reason.

After clicking the button the first time the app freezes. Log shows a java.lang.OutOfMemoryError

The json file is <200 lines which is maybe 5kb so that should not be a problem.

Any help would be much appreciated.

Does your json link actually bring back anything? I tried jsonstring.com and got nothing or am I missing something? — Mr. Concolato
– Mr. Concolato, Commented Dec 13, 2014 at 16:16
in my actual code I have a link to my personal webspace, which I left out here. I do get something back from the actual json link. — Droes
– Droes, Commented Dec 13, 2014 at 16:17
Looks to me, using that FOR loop you are adding the entries again. Is that what you really intended. — Raj
– Raj, Commented Dec 13, 2014 at 16:21

Dalija Prasnikar · Accepted Answer · 2014-12-13 16:18:47Z

5

Your program is stuck in infinite loop. You are adding cards to your cards list that keeps growing until you get out of memory

        for (int i = 0; i < cards.size(); i++ ) {
            cards.add(new Card(cards.get(i).getId(),...
        }

Loop can never finish because you test that i < cards.size() and with each new Card added cards.size increases.

answered Dec 13, 2014 at 16:18

Dalija Prasnikar♦

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1 Comment

Droes Over a year ago

That's it. Can't believe I didn't see that. Thanks for the reply!

Indra Kumar S · Accepted Answer · 2014-12-13 17:25:09Z

2

Your for loop is the cause of the error

     for (int i = 0; i < cards.size(); i++ )

And Using cards.size() in for loop is not a best practice. Instead use

     int count = cards.size();

Always use this int in for loop. This is more faster than the older one. Because In old code, every time your for loop counts for cards

edited Dec 13, 2014 at 17:25

answered Dec 13, 2014 at 16:27

Indra Kumar S

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