Develop Reference

java.lang.String cannot be converted to JSONObject

#Override
protected JSONObject doInBackground(String... params) {
String path = null;
String response = null;
HashMap<String, String> request = null;
JSONObject requestJson = null;
DefaultHttpClient httpClient = null;
HttpPost httpPost = null;
StringEntity requestString = null;
ResponseHandler<String> responseHandler = null;
// get the username and password
Log.i("Email", params[0]);
Log.i("Password", params[1]);
try {
path = "http://192.xxx.x.xxx/xxxxService/UsersService.svc/UserAuthentication";
new URL(path);
} catch (MalformedURLException e) {
e.printStackTrace();
}
try {
// set the API request
request = new HashMap<String, String>();
request.put(new String("Email"), params[0]);
request.put(new String("Password"), params[1]);
request.entrySet().iterator();
// Store locations in JSON
requestJson = new JSONObject(request);
httpClient = new DefaultHttpClient();
httpPost = new HttpPost(path);
requestString = new StringEntity(requestJson.toString());
// sets the post request as the resulting string
httpPost.setEntity(requestString);
httpPost.setHeader("Content-type", "application/json");
// Handles the response
responseHandler = new BasicResponseHandler();
response = httpClient.execute(httpPost, responseHandler);
responseJson = new JSONObject(response);
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
try {
responseJson = new JSONObject(response);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
return responseJson;
}
I'm using this code to login to my app.
responseJson = new JSONObject(response);
I'm getting "success" for the response, but responseJson value is "null"
This is what I got:
Error converting result org.json.JSONException: Value Fail of type java.lang.String cannot be converted to JSONObject
I t will be good if i can get a salution
Thanks in advance.

Try below code:
Object json = new JSONTokener(response).nextValue();
if (json instanceof JSONArray) {
JSONArray jsonArray = (JSONArray) json;
// your logic
}else if(json instanceof JSONObject){
//your logic
}

JSONArray error getting

I have login system, and i get NullPointerException after getting response or in process request generation. My login request is:
try {
if (json.getString(KEY_SUCCESS) != null) {
String res = json.getString(KEY_SUCCESS);
if(res == "sucess"){
pDialog.setMessage("Loading User Space");
pDialog.setTitle("Getting Data");
UserFunctions logout = new UserFunctions();
logout.logoutUser(getApplicationContext());
Intent upanel = new Intent(getApplicationContext(), Main.class);
upanel.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
pDialog.dismiss();
startActivity(upanel);
finish();
}else{
pDialog.dismiss();
loginErrorMsg.setText("Incorrect username/password");
}
}
}
And login building is:
public JSONArray loginUser(String email, String password, String appkey) {
String conc = email + password + appkey;
JSONArray json = jsonParser.getJSONFromUrl(loginURL + "?login=" + email
+ "&password=" + password + "&sign=" + conc);
return json;
}
In the jsonParser i have this code:
public class JSONParser {
static InputStream is = null;
static JSONArray jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
public JSONArray getJSONFromUrl(String url) {
// Making HTTP request
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
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();
// try parse the string to a JSON object
jObj = new JSONArray(json);
// return JSON String
return jObj;
}
}
By the way JSON response of the type:
{ "status": "success",
"message": "",
"session_id": "asdasddfcvxgdgfdfv",
"user":
[{ "company": "company",
"last_name": "last_name·",
"name": "name",
"middle_name": "middle_name",
"phone": "+1234567890",
"photo": "avatar.png" }] }
After this action i get error of "null values" like this:
Error converting result java.lang.NullPointerException: lock == null
Error parsing data org.json.JSONException: End of input at character 0 of

Try this way,hope this will help you to solve your problem.
public JSONObject getJSONFromUrl(String url) {
try {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpclient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
StringBuilder buffer = new StringBuilder();
BufferedReader reader = new BufferedReader(new InputStreamReader(
httpEntity.getContent(), HTTP.UTF_8));
String line = null;
try {
while ((line = reader.readLine()) != null) {
buffer.append(line);
}
} finally {
reader.close();
}
jObj = new JSONObject(reader.toString());
return jObj;
} catch (MalformedURLException localMalformedURLException) {
return null;
} catch (IOException localIOException) {
return null;
}catch (Exception e){
return null;
}
}

Your response is a JsonObject and you are parsing it to JSONArray
For more info. http://json.org/

How to parse all JSON values correctly in Android

First the: Android Code
public class MachineController extends AsyncTask<String, String,List<Machine>> {
private static String REST_URL = "...";
List<Machine> machines;
#Override
protected List<Machine> doInBackground(String... params) {
machines = new ArrayList<Machine>();
HttpClient httpClient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(REST_URL);
httpGet.addHeader("accept", "application/json");
HttpResponse response;
try {
response = httpClient.execute(httpGet);
HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream instream = entity.getContent();
BufferedReader reader = new BufferedReader(new InputStreamReader(instream));
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null)
sb.append(line + "n");
String result = sb.toString();
Gson gson = new Gson();
JsonReader jsonReader = new JsonReader(new StringReader(result));
jsonReader.setLenient(true);
JsonParser parser = new JsonParser();
JsonArray jsonArray = parser.parse(jsonReader).getAsJsonArray();
for (JsonElement obj : jsonArray) {
Machine machine = gson.fromJson(obj.getAsJsonObject().get("mobileMachine"), Machine.class);
machines.add(machine);
machines.get(0);
}
instream.close();
}
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return machines;
}
}
Here is some Code of the JSON File
[
{ "mobileMachine":
{ "condition":"VERY_GOOD",
"document":"", . . .
"mobileCategory": { "idNr":"1816e5697eb3e0c8442786be5274cb05cff04c06b4338467c8679770bff32313f7f372b5ec2f7527dad0de47d0fb117e",
"mobileCategoryEng":"Bookletmaker",
"mobileCategoryGer":"Broschuerenfertigung" },
"modelYear":2006,
Abmessungen: 665x810mm " } }
{ "mobileMachine":
{
"condition":"VERY_GOOD"," ...... } } ]
Sometimes there is a mobileCategory inside. The mobileCategoryGer and mobileCategoryEng are allways null in the List.
I can't edit the JSON File! I only want the value for mobileCategoryGer and mobileCategoryEng from the Json File. The Rest works fine. I hope u understand and can help me to parse it correctly.
(Sorry for my english)

Here you go.
Type listType = new TypeToken<List<Machine>>() {}.getType();
ArrayList<Result> results = gson.fromJson(result, listType);
Here is your complete modified code:
public class MachineController extends AsyncTask<String, String,List<Machine>> {
private static String REST_URL = "...";
List<Machine> machines;
#Override
protected List<Machine> doInBackground(String... params) {
HttpClient httpClient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(REST_URL);
httpGet.addHeader("accept", "application/json");
HttpResponse response;
try {
response = httpClient.execute(httpGet);
HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream instream = entity.getContent();
BufferedReader reader = new BufferedReader(new InputStreamReader(instream));
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null)
sb.append(line + "n");
String result = sb.toString();
Gson gson = new Gson();
Type listType = new TypeToken<List<Machine>>() {}.getType();
machines= gson.fromJson(result, listType);
instream.close();
}
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return machines;
}

You could check if it has the key with has() method. Also you can get optional value with optJSONObject() and check if it is not null.
JsonArray jsonArray = parser.parse(jsonReader).getAsJsonArray();
try {
doSomething(jsonArray);
} catch (JSONException e) {
Log.wtf("Terrible Failure", e);
}
private void doSomething(JsonArray jsonArray) throws JSONException{
for (int i=0; i<jsonArray.length(); i++){
JSONObject obj = jsonArray.getJSONObject(i);
JSONObject mobileCategory = obj.optJSONObject("mobileCategory");
if(mobileCategory !=null){
if(mobileCategory.has("mobileCategoryEng") && mobileCategory.has("mobileCategoryGer") ){
String mobileCategoryEng = mobileCategory.getString("mobileCategoryEng");
String mobileCategoryGer = mobileCategory.getString("mobileCategoryGer");
}
}
}
}

JSONObject not being correctly created (possible JSON formatting error?)

I am getting this JSON string:
[
{
"id": 135,
"date": "2013-08-30 19:00:29",
"timestamp": "2013-08-30 19:00:29",
"lat": "54.328274",
"long": "-2.747215",
"strap": "annual International Festival of Street Arts",
"link": "http://dev.website.co.uk//?p=135",
"title": "Title"
}
]
Which is correct JSON syntax im sure (works fine in the iOS app), however when parsing to a JSONObject it catches an error. Java:
public static JSONObject getJSONfromURL(String url){
//initialize
InputStream is = null;
String result = "";
JSONObject jArray = null;
//http post
try {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(url);
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
} catch (Exception e) {
Log.e("log_tag", "Error in http connection "+e.toString());
}
//convert response to string
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();
result=sb.toString();
} catch (Exception e) {
Log.e("log_tag", "Error converting result "+e.toString());
}
//try parse the string to a JSON object
try {
Log.d("log_tag", "jresult: " + result + "finish");
jArray = new JSONObject(result);
} catch (JSONException e) {
Log.e("log_tag", "Error parsing data "+e.toString());
}
return jArray;
}
Is there an error somewhere in the JSON?

[ represents a json array node
{ represents a json object node
JSONArray jArray = new JSONArray(result);
return jArray;
Also you can have one try block instead of many.

It's an array, so you need to do "new JSONArray()" instead of "new JSONObject()".

when a json string starts with [ the it will be treated as a JSONArray you need to do new JSONArray()

JSONArray is empty

I read data from a database (only the last row, I do it in my php file) what I want to do is to use the data of each field separately but the problem is that the JSONArray is empty I tried a lot of ways to do it looking for it in different posts but it´s always empty.
This is my code
public class MainActivity extends Activity {
/** Called when the activity is first created. */
JSONArray jArray = null;
String result = null;
InputStream is = null;
StringBuilder sb=null;
String ct_id;
String ct_name;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
//http post
try{
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost= new HttpPost("http://xxx.php");
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
}catch(Exception e){
Log.e("log_tag", "Error in http connection"+e.toString());
}
//convert response to string
try{
BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
sb = new StringBuilder();
String line=null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result=sb.toString();
}catch(Exception e){
Log.e("log_tag", "Error converting result "+e.toString());
}
//paring data
try{
jArray = new JSONArray(result);
JSONObject json_data=null;
for(int i=0;i<jArray.length();i++){
json_data = jArray.getJSONObject(i);
ct_id=json_data.getString("fecha");
ct_name=json_data.getString("dia");
}
}
catch(JSONException e1){
Toast.makeText(getBaseContext(), "JSON is empty" ,Toast.LENGTH_LONG).show();
} catch (ParseException e1) {
e1.printStackTrace();
}
}
}
It always catchs JSONException e1.
Thank you everibody in advance

Check returned string in result. Probably there are not only json structure(errors, warning, etc..). JSON spellchecker: http://jsonlint.com/

after checking the json response; better to try using GSON, much more convenient;
JsonParser jsonParser = new JsonParser();
JsonArray jArray;
if ( jsonParser.parse(result).isJsonArray() ) {
jArray = jsonParser.parse(result).getAsJsonArray();
}
else { jArray = new JsonArray(); }

The problem was in PHP file, JSON couldn´t understand the data and that is why it was empty, I changed it and now works properly.