Develop Reference

I'm using the answer from another SO post and I'm getting an exception JSONArray cannot be converted to JSONObject. How can I get this resolved?

Here is the answer I'm using How to implement Login with HttpURLConnection and PHP server in Android
Here is my JSONParser.java:
package com.example.android.simplejson;
import android.util.Log;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
public class JSONParser {
String charset = "UTF-8";
HttpURLConnection conn; // Connection
DataOutputStream wr; // Write
StringBuilder result;
URL urlObj;
JSONObject jObj = null;
StringBuilder sbParams;
String paramsString;
public JSONObject makeHttpRequest(String url, String method,
HashMap<String, String> params) {
sbParams = new StringBuilder();
int i = 0;
for (String key : params.keySet()) {
try {
if (i != 0){
sbParams.append("&");
}
sbParams.append(key).append("=")
.append(URLEncoder.encode(params.get(key), charset));
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
i++;
}
if (method.equals("POST")) {
// request method is POST
try {
urlObj = new URL("my_url");
conn = (HttpURLConnection) urlObj.openConnection();
conn.setDoOutput(true);
conn.setRequestMethod("POST");
conn.setRequestProperty("Accept-Charset", charset);
conn.setReadTimeout(10000);
conn.setConnectTimeout(15000);
conn.connect();
paramsString = sbParams.toString();
wr = new DataOutputStream(conn.getOutputStream());
wr.writeBytes(paramsString);
wr.flush();
wr.close();
} catch (IOException e) {
e.printStackTrace();
}
}
else if(method.equals("GET")){
// request method is GET
try {
urlObj = new URL("my_url");
conn = (HttpURLConnection) urlObj.openConnection();
conn.setDoOutput(false);
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept-Charset", charset);
conn.setConnectTimeout(15000);
conn.connect();
} catch (IOException e) {
e.printStackTrace();
}
}
try {
//Receive the response from the server
InputStream in = new BufferedInputStream(conn.getInputStream());
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
result = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
result.append(line);
Log.d("Response: ", "> " + line); //here you'll get the whole response
}
Log.d("JSON Parser", "result: " + result.toString());
} catch (IOException e) {
e.printStackTrace();
}
conn.disconnect();
// try parse the string to a JSON object
try {
jObj = new JSONObject(result.toString());
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON Object
return jObj;
}
}
Here is a snippet of my MainActivity.java:
class checkLogin extends AsyncTask<String, String, JSONObject> {
JSONParser jsonParser = new JSONParser();
private ProgressDialog pd;
private static final String LOGIN_URL = "my_url";
private static final String TAG_SUCCESS = "success";
private static final String TAG_MESSAGE = "message";
#Override
protected void onPreExecute() {
super.onPreExecute();
pd = new ProgressDialog(MainActivity.this);
pd.setMessage("Attempting login...");
pd.setIndeterminate(false);
pd.setCancelable(true);
pd.show();
}
protected JSONObject doInBackground(String... params) {
try {
HashMap<String, String> credentials = new HashMap<>();
credentials.put("username", params[0]);
credentials.put("password", params[1]);
Log.d("request", "starting");
JSONObject json = jsonParser.makeHttpRequest(
LOGIN_URL, "POST", credentials);
if (json != null) {
Log.d("JSON result", json.toString());
return json;
}
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
protected void onPostExecute(JSONObject json) {
int success = 0;
String message = "";
if (pd != null && pd.isShowing()) {
pd.dismiss();
}
if (json != null) {
Toast.makeText(MainActivity.this, json.toString(),
Toast.LENGTH_LONG).show();
try {
success = json.getInt(TAG_SUCCESS);
message = json.getString(TAG_MESSAGE);
} catch (JSONException e) {
e.printStackTrace();
}
}
if (success == 1) {
Log.d("Success!", message);
} else {
Log.d("Failure", message);
}
}
}
}
It gets a JSONArray from the server [{"AuthStatus":true,"AuthMessage":"This is my sample message","username":"username=&password="}]
My problem is the JSONArray can't be converted to JSONObject. So what can I change in my code to return the JSONArray as jObj? My ultimate goal is to set the text in my main activity as [{"AuthStatus":true,"AuthMessage":"This is my sample message","username":"username=&password="}].
Thanks!

You can't parse a JSON array as a JSON object. First you have to parse the payload as an array and then get the object from it.
public JSONObject makeHttpRequest(String url, String method,
HashMap<String, String> params) {
// ...
try {
JSONArray jArr = new JSONArray(result.toString());
jObj = jArr.getJSONObject(0);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON Object
return jObj;
}

Refer the below exampe :
String str = {"xyz":[{"name":"apple","email_id":"apple#apple.com"}]};
JSONObject json = JSONObject.fromObject(str);
So essentially your response is in format of a JSONArray [{"AuthStatus":true,"AuthMessage":"This is my sample message","username":"username=&password="}]'
where it should have been something like
{"response": [{"AuthStatus":true,"AuthMessage":"This is my sample message","username":"username=&password="}]}
or simply
{"AuthStatus":true,"AuthMessage":"This is my sample message","username":"username=&password="}
depending on your preference. If you are always going to return a single JSONObject (probably as this is a login service response) there is no need to use the square braces which makes it a JSONArray.

Error JSON Parser android app

I have a small problem with my code and I can't find why. I get the error parsing data for my email value.
The exact error is :
Error parsing data org.json.JSONException: Value Mail of type java.lang.String cannot be converted to JSONObject.
It happens after having the Log.d(request!, starting)
Here are the code.
Activity.java:
package com.example.mysqltest;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.SharedPreferences;
import android.os.AsyncTask;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class ForgotPassword extends Activity implements OnClickListener{
private EditText email;
private Button mForgotPassword;
// Progress Dialog
private ProgressDialog pDialog;
// JSON parser class
JSONParser jsonParser = new JSONParser();
//php register script
private static final String REGISTER_URL = "test";
//ids
private static final String TAG_SUCCESS = "success";
private static final String TAG_MESSAGE = "message";
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_forgot_password);
email = (EditText)findViewById(R.id.emailforf);
mForgotPassword = (Button)findViewById(R.id.forgotPassword);
mForgotPassword.setOnClickListener(this);
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
new ForgotPass().execute();
}
class ForgotPass extends AsyncTask<String, String, String> {
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(ForgotPassword.this);
pDialog.setMessage("Retrieving password...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
#Override
protected String doInBackground(String... args) {
// TODO Auto-generated method stub
// Check for success tag
int success;
String emails = email.getText().toString();
if (emails instanceof String){
Log.d("lol","ok");
}else{
Log.d("lol","not ok");
}
try {
// Building Parameters
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(ForgotPassword.this);
String userpref = prefs.getString("username","arnaud");
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("emailForgot", emails));
Log.d(userpref,"lol");
params.add(new BasicNameValuePair("username", userpref));
Log.d("request!", "starting");
//Posting user data to script
JSONObject json = jsonParser.makeHttpRequest(
REGISTER_URL, "POST", params);
// full json response
Log.d("Registering attempt", json.toString());
// json success element
success = json.getInt(TAG_SUCCESS);
if (success == 1) {
Log.d("User Created!", json.toString());
finish();
return json.getString(TAG_MESSAGE);
}else{
Log.d("Registering Failure!", json.getString(TAG_MESSAGE));
return json.getString(TAG_MESSAGE);
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
protected void onPostExecute(String file_url) {
// dismiss the dialog once product deleted
pDialog.dismiss();
if (file_url != null){
Toast.makeText(ForgotPassword.this, file_url, Toast.LENGTH_LONG).show();
}
}
}
}
JSONParser.java :
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.List;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URLEncodedUtils;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;
import android.util.Log;
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
public JSONObject getJSONFromUrl(final String url) {
// Making HTTP request
try {
// Construct the client and the HTTP request.
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
// Execute the POST request and store the response locally.
HttpResponse httpResponse = httpClient.execute(httpPost);
// Extract data from the response.
HttpEntity httpEntity = httpResponse.getEntity();
// Open an inputStream with the data content.
is = httpEntity.getContent();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
// Create a BufferedReader to parse through the inputStream.
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
// Declare a string builder to help with the parsing.
StringBuilder sb = new StringBuilder();
// Declare a string to store the JSON object data in string form.
String line = null;
// Build the string until null.
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
// Close the input stream.
is.close();
// Convert the string builder data to an actual string.
json = sb.toString();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// Try to parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// Return the JSON Object.
return jObj;
}
// function get json from url
// by making HTTP POST or GET mehtod
public JSONObject makeHttpRequest(String url, String method,
List<NameValuePair> params) {
// Making HTTP request
try {
// check for request method
if(method == "POST"){
// request method is POST
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
httpPost.setEntity(new UrlEncodedFormEntity(params));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
}else if(method == "GET"){
// request method is GET
DefaultHttpClient httpClient = new DefaultHttpClient();
String paramString = URLEncodedUtils.format(params, "utf-8");
url += "?" + paramString;
HttpGet httpGet = new HttpGet(url);
HttpResponse httpResponse = httpClient.execute(httpGet);
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 parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}
Thanks for any help.
[Edit] Here is my web service :
<?php
try {
$to = $_POST['emailForgot'];
$subject = "Test mail";
$message = "Hello! This is a simple email message.";
$from = "track_my_mate#example.com";
$headers = "From:" . $from;
mail($to,$subject,$message,$headers);
echo "Mail Sent.";
$randome = 'pierre';
$query = "UPDATE 'users' SET 'password' = ? WHERE 'id' = ? ";
//Again, we need to update our tokens with the actual data:
$query_params = array(
':pass' => $randome,
':user' => $_POST['username']
);
//time to run our query, and create the user
try {
$stmt = $db->prepare($query);
$result = $stmt->execute($query_params);
}
catch (PDOException $ex) {
// For testing, you could use a die and message.
//die("Failed to run query: " . $ex->getMessage());
//or just use this use this one:
$response["success"] = 0;
$response["message"] = "Database Error2. Please Try Again!";
die(json_encode($response));
}
} catch (Exception $e) {
$response["success"] = 0;
$response["message"] = "Please Try Again!";
}
//If we have made it this far without dying, we have successfully added
//a new user to our database. We could do a few things here, such as
//redirect to the login page. Instead we are going to echo out some
//json data that will be read by the Android application, which will login
//the user (or redirect to a different activity, I'm not sure yet..)
$response["success"] = 1;
$response["message"] = "Password Successfully Changed!";
try {
echo json_encode($response);
} catch (Exception $e) {
echo ("pierre");
}
//for a php webservice you could do a simple redirect and die.
//header("Location: login.php");
//die("Redirecting to login.php");
//}
?>
[EDIT2] I get : Mail Sent. {"success":0,"message":"Database Error2. Please Try Again !"} The problem is in my query I guess?
Arnaud

From server side,
you need to send
{"success":0,"message":"Database Error2. Please Try Again !"}
instead of
Mail Sent. {"success":0,"message":"Database Error2. Please Try Again !"}

get JSONException: Value of type java.lang.String cannot be converted to JSONObject when parsing a JSON response
Likely that your web service is not returning correct JSON.

i wanted to put some comment but i should have at list 50 reputation!!! so i should give my answer here... i had same problem with json object. use "GET" method instead of "POST". try it...
USE THIS JSON PARSER
public class JSONParser extends Activity{
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
// function get json from url
// by making HTTP POST or GET mehtod
public JSONObject makeHttpRequest(String url, String method,
List<NameValuePair> params) {
// Making HTTP request
try {
// check for request method
if(method == "POST"){
// request method is POST
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
httpPost.setEntity(new UrlEncodedFormEntity(params));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
}else if(method == "GET"){
// request method is GET
DefaultHttpClient httpClient = new DefaultHttpClient();
String paramString = URLEncodedUtils.format(params, "utf-8");
url += "?" + paramString;
HttpGet httpGet = new HttpGet(url);
HttpResponse httpResponse = httpClient.execute(httpGet);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
}
} catch (UnsupportedEncodingException e) {
Log.e("JSON PARSER", "GET OR POST");
Toast.makeText(getApplicationContext(), "Something is wrong with network!", Toast.LENGTH_LONG).show();
json="";
create_JSon_Object();
} catch (ClientProtocolException e) {
Toast.makeText(getApplicationContext(), "Something is wrong with network!", Toast.LENGTH_LONG).show();
Log.e("JSON PARSER", "GET OR POST");
json="";
return create_JSon_Object();
} catch (IOException e) {
Toast.makeText(getApplicationContext(), "Something is wrong with network!", Toast.LENGTH_LONG).show();
Log.e("JSON PARSER IO ERROR", "GET OR POST");
json="";
return create_JSon_Object();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(is, "utf-8"), 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) {
Toast.makeText(getApplicationContext(), "Something is wrong with network!", Toast.LENGTH_LONG).show();
Log.e("JSON PARSER Buffer Error", "Error converting result ");
json="";
return create_JSon_Object();
}
return create_JSon_Object();
}
private JSONObject create_JSon_Object() {
// try parse the string to a JSON object
try {
//jObj = new JSONObject(json);
jObj = new JSONObject(json);
} catch (JSONException e) {
Toast.makeText(getApplicationContext(), "Something is wrong with network!", Toast.LENGTH_LONG).show();
Log.e("JSON Parser", "Error parsing data " + e.toString());
return jObj;
}
// return JSON String
return jObj;
}
}

JSON reads me only objects, no arrays

I'm using Eclipse, for an application where I have to read a JSON file from an URL.
The code I'm using is this one:
http://collegewires.com/android/2012/06/json-parsing-in-android/
Ok, the CLASS which I'm using for reading JSON files is called Parser.java:
package com.cw.json;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;
public class Parser {
static InputStream is = null;
static JSONObject jsonObject = null;
static String json = "";
// class constructor
public Parser() {
}
public JSONObject getJSONFromUrl(String url) {
// Making HTTP request
try {
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} catch (UnsupportedEncodingException exception) {
exception.printStackTrace();
} catch (ClientProtocolException exception) {
exception.printStackTrace();
} catch (IOException exception) {
exception.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sBuilder = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sBuilder.append(line + "\n");
}
is.close();
json = sBuilder.toString();
} catch (Exception exception) {
exception.printStackTrace();
}
// Parsing the string to a JSON object
try {
jsonObject = new JSONObject(json);
} catch (JSONException exception) {
exception.printStackTrace();
}
// JSON String
return jsonObject;
}
}
I was using this code for reading a JSON file which is directly an ARRAY, but the code gives me an error.
My question is: is it possible to read an Array instead always reading an Object??
maybe using another class?

Try to modify your Parser.java to this, so you gat a Array not a Object. And please buy you a JAVA Book for beginners, so you do learn how to speak JAVA
public JSONArray getJSONFromUrl(String url) {
....
static JSONArray jsonArray = null;
....
// Parsing the string to a JSON Array
try {
jsonArray = new JSONArray(json);
} catch (JSONException exception) {
exception.printStackTrace();
}
return jsonArray;
}

Android, Web Services, AsyncTask please help a noob/make sure im starting right

Ive made edits since the orignal post Im making an android app that connects to an JSON API. Everything so far works ok except if there is a delay from the server. The UI of course can stop responding if it takes too long. Ive read that asynctask can solve my problem. Ive had a really ard time with the examples though.
Here is the restclient class making the http calls... parsing the json and storing custom objects to a public list that my other class can access.
package com.bde.dgcr;
import android.app.Activity;
import android.content.Context;
import android.os.AsyncTask;
import android.util.Log;
import android.view.View;
import android.widget.ListView;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
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 java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
public class RestClient {
static List<ResponseHolder> list = new ArrayList<ResponseHolder>();
protected Context context = this.context;
private static String convertStreamToString(InputStream is) {
/*
* To convert the InputStream to String we use the BufferedReader.readLine()
* method. We iterate until the BufferedReader return null which means
* there's no more data to read. Each line will appended to a StringBuilder
* and returned as String.
*/
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}
/* This is a test function which will connects to a given
* rest service and prints it's response to Android Log with
* labels "Praeda".
*/
public void connect(String url) {
AsyncTask<String, Void, Void> connection = new AsyncTask<String, Void, Void>() {
protected Context context;
#Override
protected Void doInBackground(String... params) {
// Prepare a request object
HttpGet httpget = new HttpGet(params[0]);
// Execute the request
HttpResponse response;
HttpClient httpclient = new DefaultHttpClient();
try {
list.clear();
response = httpclient.execute(httpget);
// Examine the response status
Log.i("Praeda", response.getStatusLine().toString());
// Get hold of the response entity
HttpEntity entity = response.getEntity();
// If the response does not enclose an entity, there is no need
// to worry about connection release
if (entity != null) {
// A Simple JSON Response Read
InputStream instream = entity.getContent();
String result = convertStreamToString(instream);
// A Simple JSONObject Creation
//JSONObject json= new JSONObject(result);
JSONArray jsonArray = new JSONArray(result);
// A Simple JSONObject Parsing
for (int i = 0; i < (jsonArray.length()); i++) {
JSONObject json_obj = jsonArray.getJSONObject(i);
ResponseHolder rh = new ResponseHolder(json_obj);
list.add(rh);
}
instream.close();
}
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void aVoid) {
ListView listView1;
super.onPostExecute(aVoid); //To change body of overridden methods use File | Settings | File Templates.
ResponseHolderAdapter adapter = new ResponseHolderAdapter(context, R.layout.listview_item_row, RestClient.list);
listView1 = (ListView) findViewById(R.id.listView1);
View header = (View) getLayoutInflater().inflate(R.layout.listview_header_row, null);
listView1.addHeaderView(header);
listView1.setAdapter(adapter);
}
};
connection.execute(url);
}
}
Here is the class calling the static connect method and using the list for an adapter to go in a list view.
public class JsonGrabber extends Activity {
private final String API_KEY = "key";
private final String SECRET = "secret";
private String state;
private String city;
private String country;
private static String mode;
private String md5;
private String url;
CourseSearch cs;
private ListView listView1;
/**
* Called when the activity is first created.
*/
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.results);
Bundle extras = getIntent().getExtras();
state = extras.getString("state");
city = URLEncoder.encode(extras.getString("city"));
country = extras.getString("country");
mode = extras.getString("mode");
md5 = MD5.getMD5(API_KEY + SECRET + mode);
System.out.println(md5);
url = "http://www.api.com/?key=" + API_KEY + "&mode=" + mode + "&id=1&sig=" + md5;
String findByLocUrl = "http://www.api.com/?key=" + API_KEY + "&mode=" + mode + "&city=" + city + "&state=" + state + "&country=" + country + "&sig=" + md5;
System.out.println(findByLocUrl);
RestClient rc = new RestClient();
rc.connect(findByLocUrl);
//RestClient.connect(findByLocUrl);
/* if (RestClient.list.isEmpty())
{
setContentView(R.layout.noresults);
} else
{
ResponseHolderAdapter adapter = new ResponseHolderAdapter(this, R.layout.listview_item_row, RestClient.list);
listView1 = (ListView) findViewById(R.id.listView1);
View header = (View) getLayoutInflater().inflate(R.layout.listview_header_row, null);
listView1.addHeaderView(header);
listView1.setAdapter(adapter);
}
*/
}
}
Somehow Im supposed to mesh all this up into using an innerclass extending asyctask to do the API calls in the background parse the json add to my list and set up the adapter. I know i may have some object orientation problems and was hoping before i continue on with my app that you guys can make sure im going in the right direction. I have a few other classes I didnt include. Let me know if it will make more sense if I added the other classes. Thanks In Advance for any help you guys/girls may be able to offer.

You can rewrite your connect method using an AsyncTask like this:
public static void connect(String url) {
HttpClient httpclient = new DefaultHttpClient();
AsyncTask<String, Void, Void> connection = new AsyncTask<String, Void, Void>() {
#Override
protected Void doInBackground(String... params) {
// Prepare a request object
HttpGet httpget = new HttpGet(params[0]);
// Execute the request
HttpResponse response;
try {
list.clear();
response = httpclient.execute(httpget);
// Examine the response status
Log.i("Praeda", response.getStatusLine().toString());
// Get hold of the response entity
HttpEntity entity = response.getEntity();
// If the response does not enclose an entity, there is no need
// to worry about connection release
if (entity != null) {
// A Simple JSON Response Read
InputStream instream = entity.getContent();
String result= convertStreamToString(instream);
// A Simple JSONObject Creation
//JSONObject json= new JSONObject(result);
JSONArray jsonArray = new JSONArray(result);
// A Simple JSONObject Parsing
for (int i = 0; i < (jsonArray.length()); i++) {
JSONObject json_obj = jsonArray.getJSONObject(i);
ResponseHolder rh = new ResponseHolder(json_obj);
list.add(rh);
}
instream.close();
}
}
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
connection.execute(url);
}

If you want to do it right, you should use a contentprovider, service, and a database, here's a good tutorial:
http://mobile.tutsplus.com/tutorials/android/android-fundamentals-downloading-data-with-services/

Problem returning an object from an AsyncTask

I have a class (RestClient.java) that extends AsyncTask:
package org.stocktwits.helper;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
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.JSONException;
import org.json.JSONObject;
import android.os.AsyncTask;
import android.util.Log;
public class RestClient extends AsyncTask<String, Void, JSONObject>{
public JSONObject jsonObj = null;
private static String convertStreamToString(InputStream is) {
/*
* To convert the InputStream to String we use the BufferedReader.readLine()
* method. We iterate until the BufferedReader return null which means
* there's no more data to read. Each line will appended to a StringBuilder
* and returned as String.
*/
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}
/* This is a test function which will connects to a given
* rest service and prints it's response to Android Log with
* labels "Praeda".
*/
public static JSONObject connect(String url)
{
HttpClient httpclient = new DefaultHttpClient();
// Prepare a request object
HttpGet httpget = new HttpGet(url);
// Execute the request
HttpResponse response;
try {
response = httpclient.execute(httpget);
// Examine the response status
Log.i("Praeda",response.getStatusLine().toString());
// Get hold of the response entity
HttpEntity entity = response.getEntity();
if (entity != null) {
// A Simple JSON Response Read
InputStream instream = entity.getContent();
String result= convertStreamToString(instream);
// A Simple JSONObject Creation
JSONObject json=new JSONObject(result);
// Closing the input stream will trigger connection release
instream.close();
return json;
}
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
#Override
protected JSONObject doInBackground(String... urls) {
return connect(urls[0]);
}
#Override
protected void onPostExecute(JSONObject json ) {
this.jsonObj = json;
}
public void setJSONObject(JSONObject jsonFromUI){
this.jsonObj = jsonFromUI;
}
public JSONObject getJSONObject(){
return this.jsonObj;
}
}
I am trying to execute the AsyncTask on my Main class (Main.java):
RestClient rc = new RestClient();
JSONObject json = new JSONObject();
rc.setJSONObject(json);
rc.execute(buildQuery());
json = rc.getJSONObject();
//do some stuff with the json object
try { JSONObject query = json.getJSONObject("query");
//...
}
json is null because it is called before onPostExecute(). How can I get my JSON?
UPDATE:
I need to run this try block in onPostExecute():
try {
JSONObject query = json.getJSONObject("query");
JSONObject results = query.getJSONObject("results");
if (query.getString("count").equals("1")) { // YQL JSON doesn't
// return an array for
// single quotes
JSONObject quote = results.getJSONObject("quote");
Quote myQuote = new Quote();
myQuote.setName(quote.getString("Name"));
myQuote.setSymbol(quote.getString("Symbol"));
myQuote.setLastTradePriceOnly(quote
.getString("LastTradePriceOnly"));
myQuote.setChange(quote.getString("Change"));
myQuote.setOpen(quote.getString("Open"));
myQuote.setMarketCapitalization(quote
.getString("MarketCapitalization"));
myQuote.setDaysHigh(quote.getString("DaysHigh"));
myQuote.setYearHigh(quote.getString("YearHigh"));
myQuote.setDaysLow(quote.getString("DaysLow"));
myQuote.setYearLow(quote.getString("YearLow"));
myQuote.setVolume(quote.getString("Volume"));
myQuote.setAverageDailyVolume(quote
.getString("AverageDailyVolume"));
myQuote.setPeRatio(quote.getString("PERatio"));
myQuote.setDividendYield(quote.getString("DividendYield"));
myQuote.setPercentChange(quote.getString("PercentChange"));
quotesAdapter.add(myQuote);}

Hey You can use listeners to fix this problem.
I've changed the code slightly to use this.
package com.insidetip.uob.data;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
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.JSONException;
import org.json.JSONObject;
import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.util.Log;
public class JSONClient extends AsyncTask<String, Void, JSONObject>{
ProgressDialog progressDialog ;
GetJSONListener getJSONListener;
Context curContext;
public JSONClient(Context context, GetJSONListener listener){
this.getJSONListener = listener;
curContext = context;
}
private static String convertStreamToString(InputStream is) {
/*
* To convert the InputStream to String we use the BufferedReader.readLine()
* method. We iterate until the BufferedReader return null which means
* there's no more data to read. Each line will appended to a StringBuilder
* and returned as String.
*/
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}
public static JSONObject connect(String url)
{
HttpClient httpclient = new DefaultHttpClient();
// Prepare a request object
HttpGet httpget = new HttpGet(url);
// Execute the request
HttpResponse response;
try {
response = httpclient.execute(httpget);
// Examine the response status
Log.i("Praeda",response.getStatusLine().toString());
// Get hold of the response entity
HttpEntity entity = response.getEntity();
if (entity != null) {
// A Simple JSON Response Read
InputStream instream = entity.getContent();
String result= convertStreamToString(instream);
// A Simple JSONObject Creation
JSONObject json=new JSONObject(result);
// Closing the input stream will trigger connection release
instream.close();
return json;
}
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
#Override
public void onPreExecute() {
progressDialog = new ProgressDialog(curContext);
progressDialog.setMessage("Loading..Please wait..");
progressDialog.setCancelable(false);
progressDialog.setIndeterminate(true);
progressDialog.show();
}
#Override
protected JSONObject doInBackground(String... urls) {
return connect(urls[0]);
}
#Override
protected void onPostExecute(JSONObject json ) {
getJSONListener.onRemoteCallComplete(json);
progressDialog.dismiss();
}
}
Use in the calling class like this.
JSONClient client = new JSONClient(context, listener);
client.execute(URL);
Dont forget to implement the listener
public interface GetJSONListener {
public void onRemoteCallComplete(JSONObject jsonFromNet);
}

I'm be mistaken by result of doInBackground can be consumed in onPostExecute
doInBackground(Params...), invoked on
the background thread immediately
after on PreExecute() finishes
executing. This step is used to
perform background computation that
can take a long time. The parameters
of the asynchronous task are passed
to this step. The result of the
computation must be returned by this
step and will be passed back to the
last step. This step can also use
publishProgress(Progress...) to
publish one or more units of
progress. These values are published
on the UI thread, in the
onProgressUpdate(Progress...) step.
#Override
protected void onPostExecute(JSONObject json ) {
// DO stuff here ( it's UI thread )
mJsonFromTheActivity = json;
}

execute() always returns the AsyncTask itself. The object you return from doInBackground() is handed to you in onPostExecute().

If you have your asynctask as a nested inner class of your activity, you can set one of your activities variables to the result of your asynctask