Read Json file in Android and Populate in ListView

Question

I write this piece of code for reading json file and show it in listview but it return empty list . I would appreciate if anybody advise me. Thanks

eventList.json:

    {
"events": [
{
"event": "Taste of day"
},
{
"event": "House Party at Park"
},
{
"event": "Farmers Markets"
},
{
"event": "Blues Festival Preview Events"
},
{
"event": "Cultural Alliance - Heritage and Fashion"
}
]
}

and this an Activity for reading and parsing json file :

     public class EventSelectActivity extends Activity {




@Override


protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_event_select);


    // Reading json file from assets folder
    StringBuffer sb = new StringBuffer();
    BufferedReader br = null;
    try {
        br = new BufferedReader(new InputStreamReader(getAssets().open(
                "eventList.json")));
        String temp;
        while ((temp = br.readLine()) != null)
            sb.append(temp);
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if ((br != null)) {
            try {
                br.close(); // stop reading
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    try {
        JSONObject jsonObjMain = new JSONObject();
        JSONArray jsonArray = jsonObjMain.getJSONArray("events");

        ArrayList<String> messages = new ArrayList<String>();
        for (int i = 0; i < jsonArray.length(); i++) {

            // Creating JSONObject from JSONArray
            JSONObject jsonObj = jsonArray.getJSONObject(i);

            // Getting data from individual JSONObject
            String message = jsonObj.getString("msg");
            messages.add(message);

        }

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(EventSelectActivity.this,
                android.R.layout.simple_list_item_1, messages);
        ListView list=(ListView)findViewById(R.id.eventList);
        list.setAdapter(adapter);
        list.setOnItemClickListener(new AdapterView.OnItemClickListener()
        {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                                    int position, long id) {
                Toast.makeText(EventSelectActivity.this, "TEST List View", Toast.LENGTH_SHORT).show();

            }
        });

    } catch (JSONException e) {
        e.printStackTrace();
    }


}

}

What is the purpose of `sb` ? Why are you instantiating an empty `jsonObjMain`? Perhaps you meant `JSONObject jsonObjMain = new JSONObject(sb);` ? — t0mm13b, May 23 '16 at 16:31
could you please explain more . I got this code from one example . thanks — saeid jafari, May 23 '16 at 16:36
Please include the reference to the example you found this from. — t0mm13b, May 23 '16 at 16:44
I change it to this but it is not working yet: JSONObject jsonObjMain = new JSONObject(sb.toString()); — saeid jafari, May 23 '16 at 16:46
stackoverflow.com/questions/29942090/solved-android-parsing-local-json-data-assets-folder — saeid jafari, May 23 '16 at 16:48
What is this "msg"? It is not in the JSON. please see my answer. — t0mm13b, May 23 '16 at 16:51
Possible duplicate of [how to display fetched json data into listview using baseadapter](http://stackoverflow.com/questions/21662673/how-to-display-fetched-json-data-into-listview-using-baseadapter) — Aditya Vyas-Lakhan, May 24 '16 at 06:33
check this first http://www.androidhive.info/2012/01/android-json-parsing-tutorial/ — Aditya Vyas-Lakhan, May 24 '16 at 06:34

t0mm13b · Answer 1 · 2016-05-23T17:26:07.940

1

The variable sb holds the consumed JSON data.

There was no reference to actual JSON object as it was empty.

JSONObject jsonObjMain = new JSONObject();

Change the code block:

try {
   JSONObject jsonObjMain = new JSONObject(sb.toString());
   JSONArray jsonArray = jsonObjMain.getJSONArray("events");
   // ...

There is a undefined reference to the JSON field, "msg", maybe it should be "event"?

// Getting data from individual JSONObject
String message = jsonArray.getString(i);
messages.add(message);

edited May 23 '16 at 17:26

answered May 23 '16 at 16:36

t0mm13b

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I do these changes but it doesn't work. it still return new activity without list view – saeid jafari May 23 '16 at 17:07

Ashwini · Answer 2 · 2016-05-24T06:18:31.587

Change to below code :

    public class JsonActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_json);

        // Reading json file from assets folder
        StringBuffer sb = new StringBuffer();
        BufferedReader br = null;
        try {
            br = new BufferedReader(new InputStreamReader(getAssets().open(
                    "eventList.json")));
            String temp;
            while ((temp = br.readLine()) != null)
                sb.append(temp);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if ((br != null)) {
                try {
                    br.close(); // stop reading
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

        try {
            JSONObject jsonObjMain = new JSONObject(sb.toString());
            JSONArray jsonArray = jsonObjMain.getJSONArray("events");

            ArrayList<String> messages = new ArrayList<String>();
            for (int i = 0; i < jsonArray.length(); i++) {
                // Creating JSONObject from JSONArray
                JSONObject object = jsonArray.getJSONObject(i);
                String message = object.getString("event");
                messages.add(message);
            }

            ArrayAdapter<String> adapter = new ArrayAdapter<String>(JsonActivity.this,
                    android.R.layout.simple_list_item_1, messages);
            ListView list = (ListView) findViewById(R.id.eventList);
            list.setAdapter(adapter);
            list.setOnItemClickListener(new AdapterView.OnItemClickListener() {

                @Override
                public void onItemClick(AdapterView<?> parent, View view,
                                        int position, long id) {
                    Toast.makeText(JsonActivity.this, "TEST List View", Toast.LENGTH_SHORT).show();

                }
            });

        } catch (JSONException e) {
            e.printStackTrace();
        }
    }


}

@saeidjafari : Check the above code. I have edited it. It will work now. — Ashwini, May 24 '16 at 06:19
Make sure you have created assets folder. Try printing "sb.toString()" if value is null or not. I tried this code and its working for me. — Ashwini, May 25 '16 at 04:21

Read Json file in Android and Populate in ListView

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