JSONArray converting object to array in Android Can't find tag

Question

I'm attempting to pull information from an API via JSON on Android. I've successfully downloaded the information, now I need to put it in the JSONArray given the tag "Categories". Ultimately this is going into a listview. Here is my code:

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.StatusLine;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.util.Log;


public class jsonParser {

    //initialize
    static JSONObject object =null;

    public jsonParser(){

    }

     public JSONObject getJSONfromURL (String url){
            //HTTP call
            try{
                URLConnection connection = new URL(url).openConnection();

                BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()), 2048 * 16);
                StringBuffer builder = new StringBuffer();
                String line;

                while ((line = reader.readLine()) != null) {
                  builder.append(line).append("\n");
                }
                String blah = builder.toString();

                //Parsing string into JSONArray
                JSONObject object = new JSONObject ( new String(builder.toString()) );
                Log.e("success","created object: " + object);

                } catch(Exception e){
                    Log.e("Http Error","Error in http connection " + e.toString());

                }


            return object;
        }
}

Here is the Logcat:

05-12 16:57:54.040: E/success(9625): created object: {"Categories":[{"id":"2","name":"Glass Repair"},{"id":"3","name":"Appliance Repair"},{"id":"4","name":"Air Conditioning"},{"id":"5","name":"Community Involvement"},{"id":"6","name":"Electrical"},{"id":"7","name":"Flooring"},{"id":"8","name":"Heating Repair"},{"id":"9","name":"Landscaping"},{"id":"10","name":"Plumbing"},{"id":"11","name":"Remodeling\/Renovation"},{"id":"12","name":"Window Coverings"}]}
05-12 16:57:54.040: E/JSON Variable(9625): json returns this value: null
05-12 16:57:54.070: E/Test JSON(9625): JSON s returns: null
05-12 16:57:54.070: W/dalvikvm(9625): threadid=1: thread exiting with uncaught exception (group=0x416bf438)
05-12 16:57:54.070: E/AndroidRuntime(9625): FATAL EXCEPTION: main
05-12 16:57:54.070: E/AndroidRuntime(9625): java.lang.NullPointerException
05-12 16:57:54.070: E/AndroidRuntime(9625):     at com.example.hstnc_activity.DisplayServiceActivity$Request.onPostExecute(DisplayServiceActivity.java:104)
05-12 16:57:54.070: E/AndroidRuntime(9625):     at com.example.hstnc_activity.DisplayServiceActivity$Request.onPostExecute(DisplayServiceActivity.java:1)
05-12 16:57:54.070: E/AndroidRuntime(9625):     at android.os.AsyncTask.finish(AsyncTask.java:631)
05-12 16:57:54.070: E/AndroidRuntime(9625):     at android.os.AsyncTask.access$600(AsyncTask.java:177)
05-12 16:57:54.070: E/AndroidRuntime(9625):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
05-12 16:57:54.070: E/AndroidRuntime(9625):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-12 16:57:54.070: E/AndroidRuntime(9625):     at android.os.Looper.loop(Looper.java:137)
05-12 16:57:54.070: E/AndroidRuntime(9625):     at android.app.ActivityThread.main(ActivityThread.java:4918)
05-12 16:57:54.070: E/AndroidRuntime(9625):     at java.lang.reflect.Method.invokeNative(Native Method)
05-12 16:57:54.070: E/AndroidRuntime(9625):     at java.lang.reflect.Method.invoke(Method.java:511)
05-12 16:57:54.070: E/AndroidRuntime(9625):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1004)
05-12 16:57:54.070: E/AndroidRuntime(9625):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:771)
05-12 16:57:54.070: E/AndroidRuntime(9625):     at dalvik.system.NativeStart.main(Native Method)

Lastly here's the JSON information (used jsonlint.com to grab this):

{
    "Categories": [
        {
            "id": "2",
            "name": "Glass Repair"
        },
        {
            "id": "3",
            "name": "Appliance Repair"
        },
        {
            "id": "4",
            "name": "Air Conditioning"
        },
        {
            "id": "5",
            "name": "Community Involvement"
        },
        {
            "id": "6",
            "name": "Electrical"
        },
        {
            "id": "7",
            "name": "Flooring"
        },
        {
            "id": "8",
            "name": "Heating Repair"
        },
        {
            "id": "9",
            "name": "Landscaping"
        },
        {
            "id": "10",
            "name": "Plumbing"
        },
        {
            "id": "11",
            "name": "Remodeling/Renovation"
        },
        {
            "id": "12",
            "name": "Window Coverings"
        }
    ]
}

Here is the ASync method:

public class Request extends AsyncTask<String, Void, JSONObject> {

    private static final int REGISTRATION_TIMEOUT = 3 * 1000;
    private static final int WAIT_TIMEOUT = 30 * 1000;
    private ProgressDialog dialog = 
            new ProgressDialog(DisplayServiceActivity.this);


    protected void onPreExecute() {
        dialog = new ProgressDialog(DisplayServiceActivity.this);
        dialog.setMessage("Getting your info real quick... Please wait...");
        dialog.show();
    }

    protected JSONObject doInBackground(String... params) {

        json = jParser.getJSONfromURL(url);
        Log.e("JSON Variable", "json returns this value: " + json);

        return json;

    }

    protected void onPostExecute(JSONObject s) {          
        super.onPostExecute(s);

        dialog.dismiss();
        Log.e("Test JSON","JSON s returns: " + s);
        try {
            directory = s.getJSONArray("Categories");
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        for(int i = 0; i< directory.length(); i++){
            String str_id = directory.optString(i, "id");
            String str_name = directory.optString(i, "name");
            displayCatList(str_id, str_name);

            Log.e("Test directory","Directory returns: " + json);
        }

    }

}

I appreciate all the help!

plz also share doInBackground method code

ρяσѕρєя K
– ρяσѕρєя K

2013-05-12 18:18:25 +00:00
Commented May 12, 2013 at 18:18 — ρяσѕρєя K
– ρяσѕρєя K, Commented May 12, 2013 at 18:18
I added it to the original post.

user1890328
– user1890328

2013-05-12 18:25:28 +00:00
Commented May 12, 2013 at 18:25 — user1890328
– user1890328, Commented May 12, 2013 at 18:25
I recommend you to use Spring for Android

Misagh Aghakhani
– Misagh Aghakhani

2013-05-12 19:17:09 +00:00
Commented May 12, 2013 at 19:17 — Misagh Aghakhani
– Misagh Aghakhani, Commented May 12, 2013 at 19:17

Vishal Pawale · Accepted Answer · 2013-05-12 21:05:58Z

1

You need to return data object from getJSONFromURL() method.

Now in doInBackground() do this->

JSONArray categories = data.getJSONArray("Categories");

now here you will have categories array.

You need to initialize your dialog under onPreExecute like this ->

protected void onPreExecute() {
    dialog = new ProgressDialog(DisplayServiceActivity.this);
    dialog.setMessage("Getting your info real quick... Please wait...");
    dialog.show();
}

Do this - >

public JSONObject getJSONfromURL (String url){
        //HTTP call
        JSONObject object = new JSONObject();
        try{
            URLConnection connection = new URL(url).openConnection();

            BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()), 2048 * 16);
            StringBuffer builder = new StringBuffer();
            String line;

            while ((line = reader.readLine()) != null) {
              builder.append(line).append("\n");
            }
            String blah = builder.toString();

            //Parsing string into JSONArray
            object = new JSONObject ( new String(builder.toString()) );
            Log.e("success","created object: " + object);

            } catch(Exception e){
                Log.e("Http Error","Error in http connection " + e.toString());

            }


        return object;
    }

edited May 12, 2013 at 21:05

answered May 12, 2013 at 18:34

Vishal Pawale

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9 Comments

user1890328 Over a year ago

I used your advice and the advice below this comment and the app still force closes because json is returning null.

Vishal Pawale Over a year ago

You were not intialiasing dialog properly, I have edited my answer

Vishal Pawale Over a year ago

Is it solving the problem?

user1890328 Over a year ago

I updated my code and it's still closing. It has something to do with the json variable returning null I think. I've updated my original post with new code / logcat

Vishal Pawale Over a year ago

Remove this line from JsonParser class -> //initialize static JSONObject object =null; And change method as I have posted in my answer

|

Sandeep · Accepted Answer · 2013-05-12 18:28:53Z

1

That is array not object. Please use below..

        json = jParser.getJSONfromURL(url);
        try {
            JSONArray array = json.getJSONArray("Categories");
            for(---){
              //do your stuff
            }
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

answered May 12, 2013 at 18:28

Sandeep

3,3445 gold badges31 silver badges56 bronze badges

Comments

ρяσѕρєя K · Accepted Answer · 2013-05-12 18:33:37Z

1

as in Log :

JSONException: No value for Categories

because you are returning object JSONObject from getJSONfromURL method which just contains id and name keys instead of Categories JSONArray.

you can get all values from object as :

try {
        String str_id = json.optString("id");
        String str_name = json.optString("name");
    } catch (JSONException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

answered May 12, 2013 at 18:33

ρяσѕρєя K

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5 Comments

user1890328 Over a year ago

Ok i redid the code and I still get a force close but the error originally is gone. I've updated my original code snippets and logcat.

ρяσѕρєя K Over a year ago

@user1890328 : just move

Log.e("Test JSON","JSON returns: " + json);         try {             directory = json.getJSONArray("Categories");         } catch (JSONException e) {             // TODO Auto-generated catch block             e.printStackTrace();         }         for(int i = 0; i< directory.length(); i++){             String str_id = directory.optString(i, "id");             String str_name = directory.optString(i, "name");             displayCatList(str_id, str_name);         }

part in onPostExecute and use s JSONObject instead of json

user1890328 Over a year ago

I updated the original post (code and logcat), same issue now s is null and the rest fails because of that.

ρяσѕρєя K Over a year ago

@user1890328: make an log also for json = jParser.getJSONfromURL(url); and let me known what u are getting in result

user1890328 Over a year ago

i added the log and it returns null. I'm updating the code above with this.

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