Java Array response instead of brackets

Question

I am trying to parse a JSON response in Java but am facing difficulty due to the response being array format, not object. I, first, referenced the this link but couldn't find a solution for parsing the JSON properly. Instead, I am receiving this error when trying to display the parsed data...

Exception in thread "main" org.json.JSONException: JSONObject["cardBackId"] not found.

Snippet for displaying data:

JSONObject obj = new JSONObject(response);
JSONArray cardBackId = (JSONArray) obj.get("cardBackId");
System.out.println(cardBackId);

Data response via Postman:

[
    {
        "cardBackId": "0",
        "name": "Classic",
        "description": "The only card back you'll ever need.",
        "source": "startup",
        "sourceDescription": "Default",
        "enabled": true,
        "img": "http://wow.zamimg.com/images/hearthstone/backs/original/Card_Back_Default.png",
        "imgAnimated": "http://wow.zamimg.com/images/hearthstone/backs/animated/Card_Back_Default.gif",
        "sortCategory": "1",
        "sortOrder": "1",
        "locale": "enUS"
    },

While without JSONObject I am pulling the data fine in Java and verified by using response.toString in STDOUT, this is my first time using json library in Java and it is important I parse this data as json. Any advice with this is helpful.

score 1 · Accepted Answer · 2018-06-11 04:02:00Z

1

The response is an array and not object itself, try this:

JSONObject obj = new JSONArray(response).getJSONObject(0);
String cardBackId = obj.getString("cardBackId");

Here is the output, along with relevant files used:

edited Jun 11, 2018 at 4:02

answered Jun 11, 2018 at 3:29

user2575725

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3 Comments

Chris Simmons Over a year ago

When trying this response, I receive this error -> Exception in thread "main" org.json.JSONException: JSONArray initial value should be a string or collection or array.

Chris Simmons Over a year ago

I tried your new response and received the same error.. Exception in thread "main" org.json.JSONException: JSONArray initial value should be a string or collection or array.

Chris Simmons Over a year ago

Worked. I needed to do JSONObect obj = new JSONArray(response.toString()).getJSONObject(0); I was missing the toString

Gokul Nath KP · Accepted Answer · 2018-06-11 03:23:12Z

0

First parse the response as JsonArray, instead of JsonObject.
Get JsonObject by iterating through the array.
Now get the value using the key.

answered Jun 11, 2018 at 3:23

Gokul Nath KP

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1 Comment

Chris Simmons Over a year ago

I tried that a bit ago but am receiving this error : Exception in thread "main" org.json.JSONException: JSONArray initial value should be a string or collection or array. This is the code i'm using that is giving me error: JSONArray arr = new JSONArray(response); for(int i = 0; i < arr.length(); i++){ JSONObject obj = arr.getJSONObject(i); String name = obj.getString("name"); System.out.println(name.toString()); }

hamilton.lima · Accepted Answer · 2018-06-11 03:28:57Z

Look at this example using Gson library, where you need to define the Datatype to define how to parse the JSON.

The key part of the example is: Data[] data = gson.fromJson(json, Data[].class);

package foo.bar;
import com.google.gson.Gson;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;

public class Main {

    private class Data {
        long cardBackId;
        String name;
    }

    public static void main(String[] args) throws FileNotFoundException {
        // reading the data from a file
        BufferedReader reader = new BufferedReader(new FileReader("data.json"));
        StringBuffer buffer = new StringBuffer();
        reader.lines().forEach(line -> buffer.append(line));
        String json = buffer.toString();

        // parse the json array
        Gson gson = new Gson();
        Data[] data = gson.fromJson(json, Data[].class);

        for (Data item : data) {
            System.out.println("data=" + item.name);
        }

    }

}

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