Develop Reference

Bug in AsyncTask causing random response

I am using an AsyncTask for a network call. If successful, it should return a JSON Array, and so far it works well on the device I test(Google nexus 5).
But on a Motorola device, it does not work. In the sense, it is not even sending a request to the server.
Here is the code :
private class SimpleTask extends AsyncTask<String, Void, String> {
ProgressDialog dialog;
#Override
protected void onPreExecute()
{
dialog = new ProgressDialog(MainActivity.this,ProgressDialog.STYLE_SPINNER);
dialog.setMessage("Loading Engine");
dialog.show();
}
protected String doInBackground(String... urls) {
String result = "";
try {
//HttpGet httpGet = new HttpGet(urls[0]);
HttpPost httpPost = new HttpPost(urls[0]);
HttpClient client = new DefaultHttpClient();
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(1);
nameValuePairs.add(new BasicNameValuePair("number",details));
httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = client.execute(httpPost);
int statusCode = response.getStatusLine().getStatusCode();
if (statusCode == 200) {
InputStream inputStream = response.getEntity().getContent();
BufferedReader reader = new BufferedReader
(new InputStreamReader(inputStream));
String line;
while ((line = reader.readLine()) != null) {
result += line;
}
}
} catch (ClientProtocolException e) {
} catch (IOException e) {
}
//Log.w("PREMIERE::::",result);
return result;
}
protected void onPostExecute(String jsonString) {
//dialog.dismiss();
try {
if ((this.dialog != null) && this.dialog.isShowing()) {
this.dialog.dismiss();
}
} catch (final IllegalArgumentException e) {
// Handle or log or ignore
} catch (final Exception e) {
// Handle or log or ignore
} finally {
this.dialog = null;
}
showData(jsonString);
}
}
private void showData(String jsonString)
{
// try
// {
Log.w("VALS:",""+jsonString);
Gson gson = new Gson();
JsonParser parser = new JsonParser();
JsonArray jArray = parser.parse(jsonString).getAsJsonArray();
SharedPreferences pref = getSharedPreferences("ActivitySession", Context.MODE_PRIVATE);
for(JsonElement obj : jArray )
{
MainPojo cse = gson.fromJson( obj , MainPojo.class);
uid.add(cse);
}
if(!uid.isEmpty())
{
new SimpleTask2().execute(URL2);
}
else
{
Snackbar.make(this.findViewById(android.R.id.content), "Invalid Credentials", Snackbar.LENGTH_LONG).show();
}
/*
}
catch (Exception e){
Snackbar.make(this.findViewById(android.R.id.content), "Check data connection", Snackbar.LENGTH_LONG).show();
e.printStackTrace();
}*/
}
And I purposefully, did not catch exception, and traced the bug via Crashlytics. The bug occurs on this line.
JsonArray jArray = parser.parse(jsonString).getAsJsonArray();
which says :
Fatal Exception: java.lang.IllegalStateException: This is not a JSON
Array.
Which I believes also occurs when the response is empty, and since I can't also trace a request in server, I believe this is because No request is being sent.(Correct me if wrong).
So, my question is : Am I missing something | or is there anything wrong in the way I defined AsyncTask?
EDIT 1
PS: I am using an HTTPS URL in this AsyncTask

In Crashalitics you can log debug messages and stack traces from exceptions that were caught. So the answer for you is to proper collect this information, and then the issue will be clear
// catch everythin n log everything
} catch (ClientProtocolException e) {
Crashlytics.logException(e);
} catch (IOException e) {
Crashlytics.logException(e);
}
also put log messages before the possible crash
Crashlytics.log("Here is the async task that keeps giving me headache");

Why doesn't the function get data from php in android?

I want to get response after post data but it fails. I want to create a login system, I have successfully submited data to php file, everything is working fine now I want to get response from same function but I'm unable to know where the issue is.
Here is the Java function:
public class PostDataGetRes extends AsyncTask<String, String, String> {
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected String doInBackground(String... strings) {
try {
postRData();
} catch (NullPointerException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(String lenghtOfFile) {
// do stuff after posting data
}
}
public void postRData() {
String result = "";
InputStream isr = null;
final String email = editEmail.getText().toString();
final String pass = editPass.getText().toString();
// Create a new HttpClient and Post Header
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://website.com/appservice.php");
try {
// Add your data
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
nameValuePairs.add(new BasicNameValuePair("id", email));
nameValuePairs.add(new BasicNameValuePair("stringdata", pass));
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
// Execute HTTP Post Request
HttpResponse response = httpclient.execute(httppost);
resultView.setText("Inserted");
HttpEntity entity = response.getEntity();
isr = entity.getContent();
//convert response to string
try{
BufferedReader reader = new BufferedReader(new InputStreamReader(isr,"iso-8859-1"),8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
isr.close();
result=sb.toString();
}
catch(Exception e){
Log.e("log_tag", "Error converting result "+e.toString());
}
//parse json data
try {
String s = "";
JSONArray jArray = new JSONArray(result);
for(int i=0; i<jArray.length();i++){
JSONObject json = jArray.getJSONObject(i);
s = s +
"Name : "+json.getString("first_name")+"\n\n";
//"User ID : "+json.getInt("user_id")+"\n"+
//"Name : "+json.getString("first_name")+"\n"+
//"Email : "+json.getString("email")+"\n\n";
}
resultView.setText(s);
} catch (Exception e) {
// TODO: handle exception
Log.e("log_tag", "Error Parsing Data "+e.toString());
}
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
} catch (IOException e) {
// TODO Auto-generated catch block
}
resultView.setText("Done");
}
And here is php code:
if($id){
$query = mysql_query("SELECT first_name FROM users where email = '$id' ");
while($row=mysql_fetch_assoc($query)){
$selectedData[]=$row;
}
print(json_encode($selectedData));
}
Please help me I have tried so far but could not achieve any results. Please help me how can I get response from php file after query execution.

At first be sure you get correct JSON object from your website - try printing it as Toast.makeText(). As far the web browsers keep the html comments away, android gets it in response.
AsyncTask objects and classes aren't designed to be made the way u provided and also you can't make any UI operations in doInBackground(). AsyncTask is made in a way to not to block GUI.
Here is a not much different example how it uses methods you have in AsyncTask class:
class Logging extends AsyncTask<String,String,Void>{
JSONObject json=null;
String output="";
String log=StringCheck.buildSpaces(login.getText().toString());
String pas=StringCheck.buildSpaces(password.getText().toString());
String url="http://www.mastah.esy.es/webservice/login.php?login="+log+"&pass="+pas;
protected void onPreExecute() {
Toast.makeText(getApplicationContext(), "Operation pending, please wait", Toast.LENGTH_SHORT).show();
}
#Override
protected Void doInBackground(String... params) {
HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet(url);
request.addHeader("User-Agent", "User-Agent");
HttpResponse response;
try {
response = client.execute(request);
BufferedReader br = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
String line="";
StringBuilder result = new StringBuilder();
while ((line = br.readLine()) != null) {
result.append(line);
}
output=result.toString();
} catch (ClientProtocolException e) {
Toast.makeText(getApplicationContext(), "Connection problems", Toast.LENGTH_LONG).show();
} catch (IOException e) {
Toast.makeText(getApplicationContext(), "Conversion problems", Toast.LENGTH_LONG).show();
}
return null;
}
#Override
protected void onPostExecute(Void w) {
try {
json = new JSONObject(output);
if(json.getInt("err")==1){
Toast.makeText(getApplicationContext(), json.getString("msg"), Toast.LENGTH_LONG).show();
}else{
String id_user="-1";
Toast.makeText(getApplicationContext(), json.getString("msg"), Toast.LENGTH_LONG).show();
JSONArray arr = json.getJSONArray("data");
for(int i =0;i<arr.length();i++){
JSONObject o = arr.getJSONObject(i);
id_user = o.getString("id_user");
}
User.getInstance().setName(log);
User.getInstance().setId(Integer.valueOf(id_user));
Intent i = new Intent(getApplicationContext(),Discover.class);
startActivity(i);
}
} catch (JSONException e) {
}
super.onPostExecute(w);
}
}
PHP file content:
$data = array(
'err' => 0,
'msg' => "",
'data' => array(),
);
$mysqli = new MySQLi($dbhost,$dbuser,$dbpass,$dbname);
if($mysqli->connect_errno){
$data['err'] = 1;
$data['msg'] = "Brak polaczenia z baza";
exit(json_encode($data));
}
if(isset($_GET['login']) && isset($_GET['pass'])){
$mysqli->query("SET CHARACTER SET 'utf8';");
$query = $mysqli->query("SELECT banned.id_user FROM banned JOIN user ON user.id_user = banned.id_user WHERE user.login ='{$_GET['login']}' LIMIT 1;");
if($query->num_rows){
$data['err']=1;
$data['msg']="User banned";
exit(json_encode($data));
}else{
$query = $mysqli->query("SELECT login FROM user WHERE login='{$_GET['login']}' LIMIT 1;");
if($query->num_rows){
$query = $mysqli->query("SELECT pass FROM user WHERE pass ='{$_GET['pass']}' LIMIT 1;");
if($query->num_rows){
$data['msg']="Logged IN!";
$query = $mysqli->query("SELECT id_user FROM user WHERE login='{$_GET['login']}' LIMIT 1;");
$data['data'][]=$query->fetch_assoc();
exit(json_encode($data));
}else{
$data['err']=1;
$data['msg']="Wrong login credentials.";
exit(json_encode($data));
}
}else{
$data['err']=1;
$data['msg']="This login doesn't exist.";
exit(json_encode($data));
}
}
}else{
$data['err']=1;
$data['msg']="Wrong login credentials";
exit(json_encode($data));
}
I have created there small dictionary $data for my app. I used its err key as a flag to know if any error appeared, msg to inform user about operation results and data to send JSON objects.
Thing you would want to do with if(response == true) if it had exist is similar to construction i used in my onPostExecute(Void w) method in AsyncTask:
if(json.getInt("err")==1){
//something went wrong
}else{
//everything is okay, get JSON, inform user, start new Activity
}
Also here is the way I used $data['data'] to get JSON response:
if($query->num_rows){
while($res=$query->fetch_assoc()){
$data['data'][]=$res;
}
exit(json_encode($data));
}

Send data from android to website but no result returned

I am totally new in java and android.. I am sure I did it wrong on the code, please help me fix it
I try to send the content of a tweet as a String from an android application to this online parser: http://demo.ark.cs.cmu.edu/parse, and I want to retrieve the result of the parsing, here is my code:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.test);
String Tobetag = urlEncode(contentTweet);
new Analyser().execute();
}
private String urlEncode(String s){
try {
return URLEncoder.encode(s,"UTF-8").replace("+", "%20");
}
catch ( UnsupportedEncodingException e) {
throw new RuntimeException(s,e);
}
}
private class Analyser extends AsyncTask<Integer, Integer, Integer>
{
private String mUrl = "http://demo.ark.cs.cmu.edu/parse?sentence=";
#Override
protected Integer doInBackground(Integer... params) {
// TODO Auto-generated method stub
try
{
DefaultHttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet();
request.setURI(new URI(mUrl + mTobetag));
HttpResponse response = client.execute(request);
InputStream in = response.getEntity().getContent();
BufferedReader reader = new BufferedReader( new InputStreamReader(in) );
String result = reader.readLine();
System.out.println("Top");
System.out.println(result);
System.out.println("Bottom");
in.close();
}
catch(Exception e)
{
Log.e("Twitter", "doInBackground_" + e.toString());
}
return new Integer(1);
}
protected void onProgressUpdate(Integer... progress) {
}
#Override
protected void onPostExecute(Integer i) {
}
}
I ran the code, no error reported but I didn't get the parse result, I only have this:
What can I do to get the result I wanted?
P.S. Also I am not sure I used the urlencoder right, it turn the slashes of the tweet content into %2F, but when I use the online parser by a browser, it shows that it doesn't change the slashed at all, please help

You are reading only the first line of the response, if you want to read the entire response you can do it like this:
String result = "";
for(String line;(line=br.readLine())!=null;){
result += line;
}
This will get you the entire http://demo.ark.cs.cmu.edu/parse page as a response, if you want the response to be only a JSON object, use this URL instead http://demo.ark.cs.cmu.edu/parse/api/v1/parse?sentence=....

variable returns null outside asynctask android

I have an asynctask which gets its data through php. The asynctask works fine, it passes the values to a global arraylist. However, when i try to call the variable on onCreate after .execute(), it returns a null size/value(s). I would like to know why this global variable returns a null when its supposed to have a value. Thanks in advance!
this is the code for asyntask:
private class get_pendingreq extends AsyncTask<String, Integer, String>
{
#Override
protected String doInBackground(String... arg0)
{
InputStream is = null;
String result = "";
try
{
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(url+"pending_requests.php");
List<NameValuePair> parameter = new ArrayList<NameValuePair>();
parameter.add(new BasicNameValuePair("email", globalVariables.accountemail));
httppost.setEntity(new UrlEncodedFormEntity(parameter));
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());
}
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());
}
return result;
}
#Override
protected void onPostExecute(String result)
{
super.onPostExecute(result);
try
{
/* JSON parsing starts here */
JSONObject jArray = new JSONObject(result);
/*globalVariables.pendingdate = new ArrayList<String>();*/
JSONArray request = jArray.getJSONArray("request");
for (int i = 0; i < request.length(); i++)
{
JSONObject e = request.getJSONObject(i);
/* puts values to arraylist<String> */
globalVariables.pendingdate.add(e.getString("date"));
}
Log.d("striiing", globalVariables.pendingdate.toString());
} catch (JSONException e)
{
e.printStackTrace();
}
}
}
Main activity:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.calendar);
new get_pendingreq().execute();
System.out.print("alalala" + globalVariables.pendingdate.size());
}//this returns null
Global Variable:
public static ArrayList<String> pendingdate = new ArrayList<String>;

Because AsyncTask not finished. Put System.out.print("finish"); in onPostExcute() and see who is printed first.

The idea behind an AsyncTask is that it runs asynchronously from the main thread, thus on a background thread. That way it doesn't block the execution of any code on the main thread.
Knowing that, the following lines will execute right after each other:
new get_pendingreq().execute();
System.out.print("alalala" + globalVariables.pendingdate.size());
Your get_pendingreq class will not do any actual work until after a small delay, meaning that after calling the first lines in above snippet, nothing has really happened. You've only instructed the platform to start the async task somewhere in the near future.
Now, the globalVariables.pendingdate field you're accessing on the second line will not have any values until the async task finishes its work. That doesn't happen until onPostExecute() is executed. In other words: you're trying to print the values at the wrong moment in time.
Simply move that print to the end of the async task's onPostExectute() method (but obviously before the return - why's that even there at all?).
I highly recommend you have a read through the AsyncTask class documentation and the Processes and Threads article.

It is clear form the name indeed AsyncTask runs Asynchronously ...
Let me explain taking your code into consideration:
new get_pendingreq().execute();
This line will create a new thread for execution and it will run
asynchronously and so the next line(i.e.System.out.print("alalala" +
globalVariables.pendingdate.size());) gets executed immidiatly after this line without waiting the async task to get executed completly.so put this system.print line inside
the post execute method...

Are u sure, that globalVariables.pendingdate.add(e.getString("date")); realy have field "data" ?

Scope of Variables in Java

In a Java Class, I have three List as fields in a class.
So I believe I made them available to the whole class? and all inner classes?
However, this does not work:
(For the example, I will only show one list here, not all three)
class Items extends ListActivity {
List<String> items = null; // field
Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// stuff
items = new ArrayList<String>();
new Task().execute();
Log.d("Size", String.valueOf(items.size()));
}
class Task extends AsyncTask<String, String, Void> {
// in this subclass, I parse items from JSON and add to List "items".
items = add(item);
}
Once I exit the task, I seem to lose the items in the List. It Logs "size 0"; if I do it inside the task, it shows the proper amount of items. Am I missing a very basic point about the scope of List variables here?
EDIT: Below is the complete Task class (slightly cleaned up for posting)
class Task extends AsyncTask<String, String, Void> {
private InputStream is = null;
private String result = "";
#Override
protected Void doInBackground(String... params) {
String url_select = "items.php";
param = new ArrayList<NameValuePair>();
param.add(new BasicNameValuePair("category", Category));
HttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url_select);
try {
httpPost.setEntity(new UrlEncodedFormEntity(param));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
// read content
is = httpEntity.getContent();
} catch (Exception e) {
Log.e("log_tag", "Error in http connection " + e.toString());
}
try {
BufferedReader br = new BufferedReader(
new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = "";
while ((line = br.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result = sb.toString();
} catch (Exception e) {
// TODO: handle exception
Log.e("log_tag", "Error converting result " + e.toString());
}
return null;
}
protected void onPostExecute(Void v) {
try {
JSONArray jArray = new JSONArray(result);
JSONObject json_data = null;
for (int i = 0; i < jArray.length(); i++) {
json_data = jArray.getJSONObject(i);
item = json_data.getString("item");
items.add(item);
Log.d("Items", item);
}
} catch (JSONException e1) {
Toast.makeText(getBaseContext(), "No items!",
Toast.LENGTH_SHORT).show();
} catch (ParseException e1) {
e1.printStackTrace();
}
}
}

I am not Android developer but isn't AsyncTask something like new Thread? If yes then you just see "size 0" because Log.d("Size", String.valueOf(items.size())); was executed before new task().execute(); updated your list.

You'll want to read through this tutorial
Basically, the default access level is package private (I could be wrong on the description), but basically it means that so long as you're in the same package you can see the member, but it is not visible to sub classes.
Try using the protected access level instead