Develop Reference

Why AsyncTask make infinity loop

i always found the answer to my Questions in StackoverFlow but not this time, so i'm trying to ask it, and i hope that you can help me, and Thanks even if you coudn't.
I'm trying to use the mysql query
Select * From `Table`
and returning a resultset from asynctask using .get() the problem is that after executing the query and getting the returned value when the asynctask tries to get back in the program he loop infinity,
PS:when i use other query like "Select * From Table Where something = other thing" it works perfectly.
here 2 methodes in my class DataBaseManager which got 2 params: Conn type connexion and member type ResultSet
/* asynctask pour la connexion*/public void Selmem(String ...a){
final class Select_member extends AsyncTask<String, Integer, ResultSet> {
#Override
protected ResultSet doInBackground(String... params) {
try {
ResultSet member2;
String myDriver = "com.mysql.jdbc.Driver";
Class.forName(myDriver).newInstance();
conn = DriverManager.getConnection(params[0], "root", "");
if(params.length==6)
member2=select_member(params[1],params[2],params[3],params[4],params[5]);
else
member2=select_member(params[1],params[2],params[3]);
conn.close();
return(member2);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
Log.i("printf","NOT SELECTED");
return null;
}
// TODO Auto-generated method stub
}
}
try {
if(a.length==6)
member=new Select_member().execute(a[0],a[1],a[2],a[3],a[4],a[5]).get();
else
member=new Select_member().execute(a[0],a[1],a[2],a[3]).get();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ExecutionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public ResultSet select_member(String ...a){
String sql;
PreparedStatement prest;
try {
if(a.length==5)
{
sql="SELECT * FROM `"+a[0]+"` WHERE "+a[1]+" = '"+a[2]+"' and `"+a[3]+"` = '"+a[4]+"'";
prest= conn.prepareStatement(sql);
}
else if (a[2].equals(""))
{
sql="SELECT * FROM `"+a[0]+"`";
prest= conn.prepareStatement(sql);
}
else
{
sql="SELECT * FROM `"+a[0]+"` WHERE `"+a[1]+"` = '"+a[2]+"'";
prest= conn.prepareStatement(sql);
}
prest= conn.prepareStatement(sql);
ResultSet member1;
member1 = prest.executeQuery();
ResultSet member2=member1;
if(member1.next())
return member2;
else
return null;
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
this is where i Call my Class to try to Select from my database, ps: the program dosen't even get to my loop (so i don't think that my loop is the problem i used the debugger to see where is the problem)
public class Deniere_Op extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_deniere__op);
Intent activite=getIntent();
DataBaseManager base=new DataBaseManager();
String login=activite.getExtras().getString("login");
base.Selmem("jdbc:mysql://10.0.2.2:3306/db_app",login , "", "");
if(base.member==null)
{
Toast.makeText(getApplicationContext(), "Aucune Transaction",Toast.LENGTH_LONG).show();
}
else
{int i=0;
do{i++;
for(int j=1;j<=6;j++)
{String concat=new String();
concat=concat.valueOf(i)+concat.valueOf(j);
String message;
try {
message = base.member.getString(j);
String a="textview"+concat;
int resID=getResources().getIdentifier(a, "id",getPackageName());
TextView text=(TextView) findViewById(resID);
text.setText(message);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
try {
base.member.next();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}while(base.member!=null);
}
}
I hope that this can make you understand my problem and helps you to help me :D :D.
the logcat hope it will help

How to parse json in the class which extends Application in android

I have an AsyncTask class which parse json data and inserts into an object, when I call it in normal activity classes it shows that data have been parsed but when I execute this on a class which extends Application then it gives zero result. Here is my class
public class AppGlobalData extends Application {
public ArrayList<YoutubeItem> gotItem= new ArrayList<YoutubeItem>();
private YouTubeParser parser;
#Override
public void onCreate() {
// TODO Auto-generated method stub
super.onCreate();
new ParserLoader().execute();
}
public class ParserLoader extends AsyncTask<Void, Void, Void> {
#Override
protected Void doInBackground(Void... params) {
Log.i("Succeed?", "Yes");
parser = new YouTubeParser(
"http://powergroupbd.com/youtube/getyoutubejson.php");
try {
gotItem = parser.parseInitiator();
} 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;
}
}
public ArrayList<YoutubeItem> getGotItem() {
return gotItem;
}
public void setGotItem(ArrayList<YoutubeItem> gotItem) {
this.gotItem = gotItem;
}
}
I cant figure out the problem, can anyone help?
please be noted that this class runs and logs my String but doesnt parse data.

I think what might happen is that when new ParserLoader().execute(); it doing the work asynchronously. When your Activity load and call the getGotItem() the Asynctask might not have finished

onPostExecute not being called by ASyncTask execute()

I can't explain why onPostExecute is not being called in my code. I have successfully used almost this exact code with a different app before. It prints 'onPreExecute' and the successful result of the JSON fetch from doInBackground just before return result; but then onPostExecute doesn't print anything - with the super call or not - and moreover doesn't return my string to the UI thread. Any ideas?
public class PrivateLoadFromServer extends AsyncTask<String, Integer, String> {
InputStream is = null;
String result = null;
String error_text="";
JSONObject j = null;
String url;
SQLiteOpenHelper helper;
CustomActivity activity;
private Context context;
private ProgressDialog dialog;
private int count;
String employee;
String text;
public PrivateLoadFromServer(CustomActivity activity,String employee,String url){
this.url=url;
this.employee=employee;
this.activity=activity;
}
#Override
protected void onPreExecute() {
system.out.println("onPreExecute");
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
System.out.println("onPostExecute");
activity.setJSONResult(result);
/*
if(result!=null){
System.out.println("Task reported successful");
taskHandler.taskSuccessful(this.result);
activity.setJSONResult(this.result);
} else {
taskHandler.taskFailed();
}
*/
//return;
}
#Override
protected String doInBackground(String... params) {
System.out.println("Running aSyncTask");
// Successful code to get JSON result string from server omitted.
System.out.println("Raw at doInBackground: " + result);
return result;
EDIT: Should've posted this originally, I call it as an inner class in CustomActivity like this:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
helper=new DBHelper(this);
loadBasicData();
}
private void loadBasicData() {
// If you can encode all of these into one JSON Object, cool.
String url="*****" //Omitted URL.
String employee=null;
PrivateLoadFromServer syncTask = new PrivateLoadFromServer(this,employee,url);
syncTask.execute();
try {
syncTask.get(15000, TimeUnit.MILLISECONDS);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ExecutionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (TimeoutException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println("JSONResult at Activity:"+jsonResult); // jsonResult is null
}
}
public void setJSONResult(String result){
System.out.println("setJSONResult"+result);
this.jsonResult=result; // jsonResult is a field in the Activity.
}

Because you are calling get, the JSON result is also returned from this method (see the source code of AsyncTask.java. So you can call your method directly on the output.
try {
setJSONResult(syncTask.get(15000, TimeUnit.MILLISECONDS));
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
} catch (TimeoutException e) {
e.printStackTrace();
}

Check if your are explicitly cancelling AsyncTask somewhere in the code before it could postExecute.

onPostExecute() is called on the main UI thread. If its not getting called, it means your UI thread is blocked doing something else.

Parsing multiple JSON strings

I would like to thank all the users in this community for helping me get as far as I am in my project today.
I now need your help once again. So far, I am able to establish a connection in my project from this JSON link (REMOVED FOR PRIVACY CONCERNS)
The problem is I am only able to parse one string, (firstName)
Here is my code:
public class JSONActivity extends Activity {
static TextView http;
HttpClient client;
JSONObject json;
final static String URL = "REMOVED FOR PRIVACY CONCERNS
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
http = (TextView) findViewById(R.id.http);
client = new DefaultHttpClient();
new Read().execute("firstName");
}
public JSONObject getpw(String password) throws ClientProtocolException,
IOException, JSONException {
StringBuilder url = new StringBuilder(URL);
url.append(password);
HttpGet get = new HttpGet(url.toString());
HttpResponse r = client.execute(get);
int status = r.getStatusLine().getStatusCode();
if (status == 200) {
HttpEntity e = r.getEntity();
String data = EntityUtils.toString(e);
JSONObject getname = new JSONObject(data);
return getname;
} else {
Toast.makeText(JSONActivity.this, "error", Toast.LENGTH_SHORT);
return null;
}
}
public class Read extends AsyncTask<String, Integer, String> {
#Override
protected String doInBackground(String... arg0) {
// TODO Auto-generated method stub
try {
json = getpw("trustme");
return json.getString("firstName");
} 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(String result) {
// TODO Auto-generated method stub
http.setText(result);
}
}
}
My question is, how can I parse multiple strings rather than just "firstName"?

You can get it all by doing the following:
String firstname = json.getString("firstName");
String lastname = json.getString("lastName");
int checkedIn = json.getInt("checkedIn");
int updated = json.getInt("checkedindatetime");
JSONObject address = json.getJSONObject("address");
String streetaddress = address.getString("streetAddress");
String city = address.getString("city");
etc...
JSONArray phoneNumbers = json.getJSONArray("phoneNumber");
String type = phoneNumbers.getJSONObject(0).getString("type");
etc...
Hope this helps.
A good resource for looking at json, is this validator.

Parsing Google Shopping Json Search Results

After a few weeks of trying numerous examples found here and it seems throughout the web, I'm stumped. I can retrieve the desired search results from Google Shopping just fine:
{ "items": [ { "product": {
"title": "The Doctor's BrushPicks Toothpicks 250 Pack",
"brand": "The Doctor's" } } ] }
My problem is that I have the data sitting in a string, how do I extract the two values (title,brand) in order to use them elsewhere in the program?
Here is the class in question:
public class HttpExample extends Activity {
TextView httpStuff;
DefaultHttpClient client;
JSONObject json;
final static String URL = "https://www.googleapis.com/shopping/search...";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.httpex);
httpStuff = (TextView) findViewById(R.id.tvHttp);
client = new DefaultHttpClient();
new Read().execute("items");
}
public JSONObject products(String upc) throws ClientProtocolException, IOException, JSONException {
StringBuilder url = new StringBuilder(URL);
url.append(upc);
HttpGet get = new HttpGet(url.toString());
HttpResponse r = client.execute(get);
int status = r.getStatusLine().getStatusCode();
if (status == 200) {
HttpEntity e = r.getEntity();
String data = EntityUtils.toString(e);
JSONObject timeline = new JSONObject(data);
return timeline;
} else {
Toast.makeText(HttpExample.this, "error", Toast.LENGTH_SHORT);
return null;
}
}
public class Read extends AsyncTask<String, Integer, String> {
#Override
protected String doInBackground(String... params) {
// TODO Auto-generated method stub
try {
String upc = ExportMenuActivity.upc;
json = products(upc);
return json.getString(params[0]);
} 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(String result){
httpStuff.setText(result);
}
}
}
The output of httpStuff.setText(result):
[{"product":{"brand":"The Doctor's, "title":"The Doctor's..."}}]

A solution that'd work on all versions of Android would look something like this:
JSONObject products = products(jsonStr);
JSONArray itemArray = products.getJSONArray("items");
for(int i=0; i<itemArray.length(); i++) {
if(itemArray.isNull(i) == false) {
JSONObject item = itemArray.getJSONObject(i);
String title = item.getString("title");
String brand = item.getString("brand");
}
}
JsonReader is nice, but is only available in API 10 and up. So it might or might not work for you.

You should use a JsonReader for reading the json string. Its very easy and well documented with very good sample.. here