can't get json array in android

Question

I'm trying to get json data from a php script into my android application but the getJSONFromUrl(URL); doesn't work. Below is my code..

MAINACTIVITY CLASS

public class MainActivity extends Activity {
private static final String URL = "http://10.0.2.2:1234/main.php/";
private JSONArray words = null;
private ArrayList<String> wordsList;
private static final String TAG_WORDS = "words";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    wordsList = new ArrayList<String>();
    updateJSONdata();
    Toast.makeText(getApplicationContext(), wordsList.toString(),
            Toast.LENGTH_LONG).show();
}

public void updateJSONdata() {      
    JSONParser jParser = new JSONParser();
    JSONObject json = jParser.getJSONFromUrl(URL);// this is where the error is
    try {
        words = json.getJSONArray(TAG_WORDS);
        for (int i = 0; i < words.length(); i++) {
            JSONObject c = words.getJSONObject(i);
            String title = c.toString();
            wordsList.add(title);
        }
    } catch (JSONException e) {
        e.printStackTrace();
    }
}
}

JSONParser Class

public class JSONParser {

static InputStream is = null;
static JSONObject jObj = null;
static String json = ""; 
public JSONParser() {
}    

public JSONObject getJSONFromUrl(final String url) {
    try {
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(url);
        HttpResponse httpResponse = httpClient.execute(httpPost);
        HttpEntity httpEntity = httpResponse.getEntity();
        is = httpEntity.getContent();
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    try {
        BufferedReader reader = new BufferedReader(new InputStreamReader(
                is, "iso-8859-1"), 8);
        StringBuilder sb = new StringBuilder();
        String line = null;
        while ((line = reader.readLine()) != null) {
            sb.append(line + "\n");
        }
        is.close();
        json = sb.toString();
    } catch (Exception e) {
        Log.e("Buffer Error", "Error converting result " + e.toString());
    }       
    try {
        jObj = new JSONObject(json);
    } catch (JSONException e) {
        Log.e("JSON Parser", "Error parsing data " + e.toString());
    }       
    return jObj;
}   
}

JSON data from main.php

{"words":[["bra"],["fie"]],"success":1}

PHP code:

<?php
$username = "root"; 
$password = ""; 
$host = "localhost"; 
$dbname = "dictionary_db"; 
$con=mysql_connect($host, $username, $password);
if(!$con) die('could not connect'. mysql_error());
mysql_select_db($dbname,$con);
$query = "SELECT word from local_words" ;
$result=mysql_query($query) or die(mysql_error());
$count = 0;
$wordsArr = array();
$response["words"] = array();
while ($row = mysql_fetch_row($result)){
    array_push($wordsArr,$row);
    $count++;
}
$response["success"] = 1;   
$response["words"] = $wordsArr;
echo json_encode($response);
?>

Error message in LogCat:

Buffer Error : Error converting result.lang.NullPointerException: lock == null
JSON Parser : Error parsing data org.json.JSONException: End of input at character 0 of

''' "words":[word1,word2] ''' is enum items. You should use getNames method. — nurisezgin
– nurisezgin, Commented Mar 23, 2014 at 9:28

aravind · Accepted Answer · 2014-03-23 16:26:53Z

1

{"success":1,"words":[word1,word2]} is not a valid JSON. A valid JSON should look like this

{"success":1,"words":["word1","word2"]}

Check your server response if the JSON is being sent correctly. It would help if you add more info what and how exactly your server returns the JSON.

UPDATE

You have two errors -

Buffer Error - lock == null. Reason - You are passing a null value to InputStreamReader, i.e. httpEntity.getContent(); is null.
JSON Error - the parser is trying to parse an empty string, i.e at character 0

Either the HTTP POST method is not supported or there is some other error from server. You need to check the status of httpResponse and log that too. That will nail down the problem

Another Update

You are getting Socket Exception - Permission Denied, the problem here is you haven't added the Internet permission to the app. Go to your manifest, and add the below permission

<uses-permission android:name="android.permission.INTERNET"/>

Try it and let me know if it helps.

edited Mar 23, 2014 at 16:26

answered Mar 23, 2014 at 9:22

aravind

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5 Comments

aravind Over a year ago

Please update it on your question post along with printing how it appears on a browser if the url is called directly in the address bar

Capton Over a year ago

Please i'm having issues logging the httpResponse status. Can you please help me out? I'm a bit novice in android.

aravind Over a year ago

Try logging the status using httpRespons.getStatusLine() and update

Capton Over a year ago

output of: Log.d("httpresponse", "Status code is "+ httpResponse.getStatusLine().getStatusCode()); is: java.net.SocketException: Permission denied

aravind Over a year ago

Looks like you are missing the internet permission in your manifest. Updated my answer with it, check it out

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