I have a map that i want to update from a separate thread. Im having some issues when i try to update the UI from my class that extends asynctask. And when i move the code to a handler in the main thread i get NetworkOnMainThreadException. Below is my asynctask. Is there any way to modify it to make it work?
#Override
protected Integer doInBackground(Void... params) {
try {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://83.xx.xx:8080/android/service.php");
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
nameValuePairs.add(new BasicNameValuePair("action", "getusers"));
nameValuePairs.add(new BasicNameValuePair("interval", Integer.toString(interval)));
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
String jsonString = EntityUtils.toString(response.getEntity());
Gson gson = new GsonBuilder().create();
Type listType = new TypeToken<ArrayList<User>>() {}.getType();
ArrayList<User> userList = gson.fromJson(jsonString, listType);
((GoogleMapsActivity) activity).removeOverlayItems();
for(User user : userList ){
((GoogleMapsActivity) activity).addOverlayItem(Double.parseDouble(user.last_lat), Double.parseDouble(user.last_lng), user.bluetooth_name, "test desc");
}
return 1;
} catch (Exception e) {
e.printStackTrace();
}
return null;
Rather than touching the map in your doInBackground, return your data into onPostExecute. Then update the map from onPostExecute.
Please note that you should never retain a reference to your Activity from inside your AsyncTask or you could cause a memory leak.
Ideally, you should create an observer that can return data to your Activity.
interface Observer {
public void onMyDataAvailable(MyDataClass data);
}
Then, you instantiate your AsyncTask with a reference to this observer.
class MyAsyncTask extends AsyncTask ...
private Observer observer;
public MyAsyncTask(Observer observer) {
mObserver = observer;
}
public synchronized void onActivityDestroyed() {
mObserver = null;
}
public synchronized void onPostExecute(MyDataClass result) {
if (mObserver != null) {
mObserver.onMyDataAvailable(result);
}
}
Just make sure you call onActivityDestroyed() from your activity's onDestroy method. Otherwise your Activity will leak.
Related
i wrote those threads:
How to manage multiple Async Tasks efficiently in Android
Running multiple AsyncTasks at the same time -- not possible?
but didnt find answer for my question, maybe someone can help..
I have android app which makes Login POST and getting json response,
if the Json is OK i need to POST another data to get another response.
i have extends Async Class which doing the post to the URL:
public class AsyncHttpPost extends AsyncTask<String, String, String> {
private HashMap<String, String> mData = null;
public AsyncHttpPost(HashMap<String, String> data) {
mData = data;
}
#Override
protected String doInBackground(String... params) {
byte[] result = null;
String str = "";
HttpClient client = new DefaultHttpClient();
HttpPost post = new HttpPost(params[0]);// in this case, params[0] is URL
try {
ArrayList<NameValuePair> nameValuePair = new ArrayList<NameValuePair>();
Iterator<String> it = mData.keySet().iterator();
while (it.hasNext()) {
String key = it.next();
nameValuePair.add(new BasicNameValuePair(key, mData.get(key)));
}
post.setEntity(new UrlEncodedFormEntity(nameValuePair, "UTF-8"));
HttpResponse response = client.execute(post);
StatusLine statusLine = response.getStatusLine();
if(statusLine.getStatusCode() == HttpURLConnection.HTTP_OK){
result = EntityUtils.toByteArray(response.getEntity());
str = new String(result, "UTF-8");
}
}
catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
catch (Exception e) {
return null;
}
return str;
}
#Override
protected void onPostExecute(String result) {
try {
JSONArray Loginjson = new JSONArray(result);
strStt = Loginjson.getJSONObject(0).getJSONObject("fields").getString("status");
if (strStt.equals("ERR")) {
ErrorMsg("Authentication failed");
} else if (strStt.equals("OK")) {
ErrorMsg("Login OK!!!");
ClientPage();
} else {
ErrorMsg("Connection Error");
}
} catch (JSONException e) {
ErrorMsg("Connection Error");
}
}
}
Now - i need to get another POST if the status is Error. do i need to make another Async class? with the same all procedures ? the issue is only the onPostExecute part is different.. actually the "doInBackground" will be always the same..
any idea how can i easily do multiple posts in the same activity?
Firstly, since your doInBackground() code will always stay the same, I recommend you move it into a general utility class.
Beyond that, you can go one of two ways:
Create a new AsyncTask for each type of request that can call your utility class, and have its own onPostExecute()
Create one AsyncTask that has a flag in it, which can be checked in the onPostExecute() method to see what code needs to be executed there. You will have to pass the flag in in the constructor or as a parameter in execute.
You can use a parameter at AsyncHttpPost constructor/execute or global variable to indicate if it is first or second POST (by other words - a flag). Then just create and execute another instance of AsyncHttpPost in onPostExecute (only if parameter/variable is set as "first POST").
I am new to android development. I have a AsyncTask function in my application. Calling http request from all activities. Now in each activity I am using the following class to connect to server, in some activities I even called twice !!.
Basically I am a web developer and in such cases we use a single class which can be accessed from entire application(web) and use the common function to do the same activity. The only difference is input and out put will be changed.
My doubt is in this case can I use ( convert) this to such a function or class ?
My assume is
Create an android class ( which can be accessed from all the activities )
Just make the JSON string we need with specific server ( for process in server )
Just pass the created json to the created class and then made the http connect )
Process the returned data from server
Pass that to the corresponding activity
So that I can use the same function for all the activities and I can avoid duplicate query
Can I convert this code to such a manner ?
My Code
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRequestedOrientation (ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
setContentView(R.layout.activity_main);
LogIN loginUser = new LogIN();
LoginUser.execute("");
}
private class LogIN extends AsyncTask<String, Integer, String> {
#Override
protected String doInBackground(String... sUrl) {
try {
String path = "http://www.domain_name.com/app/checkSession.php";
HttpClient client = new DefaultHttpClient();
HttpConnectionParams.setConnectionTimeout(client.getParams(), 10000);
HttpResponse response;
JSONObject json = new JSONObject();
try {
HttpPost post = new HttpPost(path);
json.put("access_token", "123456");
post.setHeader("json", json.toString());
StringEntity se = new StringEntity(json.toString());
se.setContentEncoding((Header) new BasicHeader(HTTP.CONTENT_TYPE, "application/json"));
post.setEntity(se);
response = client.execute(post);
/* Checking response */
if (response != null) {
InputStream in = response.getEntity().getContent();
String a = convertStreamToString(in);
JSONObject jsono = stringToJsonobj(a);
String passedStringValue = jsono.getString("result");
if(passedStringValue.equals("1")){
flags=1;
//Log.v("TAGG", "Success");
}
else {
flags=0;
//Log.v("TAGG", "Failed !");
}
}
} catch (Exception e) {
e.printStackTrace();
}
} catch (Exception e) {
}
return null;
}
#Override
protected void onPreExecute() {
super.onPreExecute();
showDialogue("Login Processing", "Loading");
}
#Override
protected void onProgressUpdate(Integer... progress) {
super.onProgressUpdate(progress);
}
#Override
protected void onPostExecute(String result) {
if(flags.equals(1)){
Itent homepage = new Intent(MainActivity.this, RegisterDevice.class);
startActivity(homepage);
finish();
}
else {
Intent homepage = new Intent(MainActivity.this, LoginActivity.class);
startActivity(homepage);
finish();
}
super.onPostExecute(result);
}
}
}
Please any one help/advise
Thanks in advance
Extract your class to a different file and make it public
public class LogIN extends AsyncTask<Object, Integer, String> {
private ILoginListener listener;
#Override
protected String doInBackground(Object... arg0) {
try {
this.listener = (ILoginListener) arg0[0];
//You can also send the url in the obj array
String theUrl = (String) arg0[1];
String path = "http://www.domain_name.com/app/checkSession.php";
HttpClient client = new DefaultHttpClient();
HttpConnectionParams.setConnectionTimeout(client.getParams(), 10000);
HttpResponse response;
JSONObject json = new JSONObject();
try {
HttpPost post = new HttpPost(path);
json.put("access_token", "123456");
post.setHeader("json", json.toString());
StringEntity se = new StringEntity(json.toString());
se.setContentEncoding((Header) new BasicHeader(HTTP.CONTENT_TYPE, "application/json"));
post.setEntity(se);
response = client.execute(post);
/* Checking response */
if (response != null) {
InputStream in = response.getEntity().getContent();
String a = convertStreamToString(in);
JSONObject jsono = stringToJsonobj(a);
String passedStringValue = jsono.getString("result");
if(passedStringValue.equals("1")){
flags=1;
//Log.v("TAGG", "Success");
}
else {
flags=0;
//Log.v("TAGG", "Failed !");
}
}
} catch (Exception e) {
e.printStackTrace();
}
} catch (Exception e) {
}
return null;
}
#Override
protected void onPreExecute() {
super.onPreExecute();
showDialogue("Login Processing", "Loading");
}
#Override
protected void onProgressUpdate(Integer... progress) {
super.onProgressUpdate(progress);
}
#Override
protected void onPostExecute(String result) {
listener.logInSessionCheckListener(flag.equals(1));
super.onPostExecute(result);
}
}
Regarding your other question, I normally have an interface for that, something like this:
public interface ILoginListener {
public void logInSessionCheckListener(SomeNeeded Value);
}
I implement the interface in the class where i need the postExecute result and in the overriden method you can to what you want with the result of your task.
Your class where you user it will look something like this:
public class SomeClass implements ILoginListener {
//Call it like this from any class:
LogIN loginTask = new LogIn();
Object[] someParams = new Object[2];
//add the listener
someParams[0] = SomeClass.this
//add the url
someParams[1] = someUrlString;
loginTask.execute(someParams);
#Override
public void logInSessionCheckListener(SomeNeeded Value){
//do Stuff with your results
}
}
You can do it like make separate class for everything inside doInBackground() method and called it in all activity with passing parameter to
LogIN loginUser = new LogIN(yourparameter);
LoginUser.execute("");
and check parameter in AsyncTask Class constructor like
public LogIN(Myparameter){
// Your data
}
On the other hand you can use this great framework for android : android-query and the async API.
It allows you to perform asynchroneous network tasks from activities and easily work with the results of your requests.
You should use interfaces to implement a callback to your ui activity.
Have a look at this thread, it might be useful:
android asynctask sending callbacks to ui
And your asyntask class should be in a seperate java file with public acces.
And to pass the parametres you simply have to call a new LogIN async Task like this:
new LogIN().execute(urls);
Hope it helped :)
Remember that you can never know when AsyncTask is going to finish. So if you're using this to authenticate users and then perform task X, task Y, or task Z,
then maybe it's better to create a Login helper class
public class LoginHelper {
public boolean login(params){
// Authenticate user and return true if successfull
}
}
and then have in your Activity classes
private class X extends AsyncTask {
#Override
protected String doInBackground(String... sUrl) {
...
boolean authenticated = LoginHelper.login(params...);
if(authenticated == true) {
// Perform task X here...
} else {
// Inform the user that the login failed...
}
}
First of all
You have to pass the context in which you are calling your async task
Sample Code
Login loginTask = new Long(getContext());
loginTask.execute();
You class Login should have a constructor that accepts the Context
Sample Code
public class Login extends AsyncTask<String, Integer, String> {
private Context mContext ;
private ProgressDialog pd;
private Handler handler = new Handler { };
public Login (Context context){
mContext = context ;
}
.....
Then make sure to create the method showDialog inside Login class to show the progress dialog
Note
You can add what ever Constructors you need to customize the behaviour of your Login task
for example : pass boolean parameter to tell that the Login Task is cancelable....
Hope that help you :)
I'm developing an Android app. I want to post to a server using asynctask. However, I still have an error which indicates that the UI thread is blocked.
I want to parse the XML response and display it in a list view, but I cannot proceed because the UI thread is still blocked.
public class AsynchronousPost extends ListActivity implements OnClickListener {
EditText SearchValue;
Button SearchBtn;
String URL = "";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.search_interface);
SearchBtn = (Button) findViewById(R.id.searchbtn);
SearchBtn.setOnClickListener(this);
}
public void onClick(View views) {
new MyAsyncTask().execute();
}
private class MyAsyncTask extends AsyncTask<String, Integer, Document> {
private final String URL = "url";
private final String username = "username";
private final String password = "password";
private EditText SearchValue;
#Override
protected Document doInBackground(String... arg0) {
// TODO Auto-generated method stub
getXmlFromUrl(URL); // getting XML
return null;
}
#Override
protected void onPostExecute() {
//want to parse xml response
//display on listview
}
public String getXmlFromUrl(String url) {
String xml = null;
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
SearchValue = (EditText) findViewById(R.id.search_item);
String Schvalue = SearchValue.getText().toString();
// Add your data
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(
5);
nameValuePairs
.add(new BasicNameValuePair("username", username));
nameValuePairs
.add(new BasicNameValuePair("password", password));
nameValuePairs.add(new BasicNameValuePair("searchItem",
Schvalue));
// response stored in response var
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
xml = EntityUtils.toString(httpEntity);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
return null;
} catch (ClientProtocolException e) {
e.printStackTrace();
return null;
} catch (IOException e) {
e.printStackTrace();
return null;
}
// return XML
return xml;
}
}
}
There are a couple problems that I see. First, you aren't passing anything in execute() but in your class declaration you are telling doInBackground() to expect a String. Secondly, you are telling onPostExecute() to expect a Document but you are returning null from doInBackground() and not taking any parameters in onPostExecute(). Unless I missed something, I don't see how this even compiles
protected Object doInBackground(String... params) {
//this method of AsyncTask is not running on the UI Thread -- here do just non UI taks
return result;
}
#Override
protected void onPostExecute(Object result) {
//I'm not sure but I think this method is running on the UI Thread
//If you have long operations here to do you will block UI Thread
//put the tasks in the doInBackground...
//to fill the elements in the UI elements use
//
runOnUiThread (new Runnable() {
#Override
public void run() {
//here fill your UI elements
}});
}
I am not reaching an onPostExecute in an AsyncTask Class.
I call the task this way, inside an onClick in a dialog box:
new HelpfulTask().execute(passing);
Note: When I hover over the above code, I get a warning:
A generic Array of ArrayList is created for a varargs
parameter.
I am not sure what that means and if that is preventing my Task from even running?
Here is the Task Code:
protected class UnHelpfulTask extends
AsyncTask<ArrayList<String>, Void, ArrayList<String>> {
ArrayList<String> passed;
protected ArrayList<String> doInBackground(ArrayList<String>... passing) {
passed = passing[0];
String url_select = "http://www.---.com/---/bad.php";
ArrayList<NameValuePair> param = new ArrayList<NameValuePair>();
param.add(new BasicNameValuePair("item", passed.get(0)));
param.add(new BasicNameValuePair("text", passed.get(1)));
param.add(new BasicNameValuePair("category", passed.get(2)));
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());
}
return null;
}
InputStream is = null;
String result = "";
protected void onPostExecute(Void v) {
Toast.makeText(getContext(), "You have voted this down!",
Toast.LENGTH_SHORT).show();
}
}
I get no errors on run and in the onPostExecute, the Toast never shows. (Note: This is an inner class inside of an ArrayAdapter.) I also added a toast to see if my ArrayList was unwrapping properly and put that in the onPostExecute but it never showed either.
How can I test to see if this Task is even running?
Change
protected void onPostExecute(Void v) {
so it is
protected void onPostExecute(ArrayList<String> arr)
Or change your AsyncTask declaration so it
extends AsyncTask<ArrayList<String>, Void, Void>
Which is the better idea since you return null in doInBackground(). The reason why you weren't getting the toast is because you were making a different method than what your AsyncTask specifies. This is why we ususally use the #Override annotation - it forces a check for actual overrides, which you need to do in classes like AsyncTasks.
Please can anyone tell me how to make an http post to work in the background with AsyncTask and how to pass the parameters to the AsyncTask? All the examples that I found were not clear enough for me and they were about downloading a file.
I'm running this code in my main activity and my problem is when the code sends the info to the server the app slows down as if it is frozen for 2 to 3 sec's then it continues to work fine until the next send. This http post sends four variables to the server (book, libadd, and time) the fourth is fixed (name)
Thanks in advance
public void SticketFunction(double book, double libadd, long time){
Log.v("log_tag", "%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% SticketFunction()");
//HttpClient
HttpClient nnSticket = new DefaultHttpClient();
//Response handler
ResponseHandler<String> res = new BasicResponseHandler();
HttpPost postMethod = new HttpPost("http://www.books-something.com");
try {
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(5);
nameValuePairs.add(new BasicNameValuePair("book", book+""));
nameValuePairs.add(new BasicNameValuePair("libAss", libass+""));
nameValuePairs.add(new BasicNameValuePair("Time", time+""));
nameValuePairs.add(new BasicNameValuePair("name", "jack"));
//Encode and set entity
postMethod.setEntity(new UrlEncodedFormEntity(nameValuePairs, HTTP.UTF_8));
//Execute
//manSticket.execute(postMethod);
String response =Sticket.execute(postMethod, res).replaceAll("<(.|\n)*?>","");
if (response.equals("Done")){
//Log.v("log_tag", "!!!!!!!!!!!!!!!!!! SticketFunction got a DONE!");
}
else Log.v("log_tag", "!!!!!!!?????????? SticketFunction Bad or no response: " + response);
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
//Log.v("log_tag", "???????????????????? SticketFunction Client Exception");
} catch (IOException e) {
// TODO Auto-generated catch block
//Log.v("log_tag", "???????????????????? IO Exception");
}
}
}
At first,
You put a class like following:
public class AsyncHttpPost extends AsyncTask<String, String, String> {
interface Listener {
void onResult(String result);
}
private Listener mListener;
private HashMap<String, String> mData = null;// post data
/**
* constructor
*/
public AsyncHttpPost(HashMap<String, String> data) {
mData = data;
}
public void setListener(Listener listener) {
mListener = listener;
}
/**
* background
*/
#Override
protected String doInBackground(String... params) {
byte[] result = null;
String str = "";
HttpClient client = new DefaultHttpClient();
HttpPost post = new HttpPost(params[0]);// in this case, params[0] is URL
try {
// set up post data
ArrayList<NameValuePair> nameValuePair = new ArrayList<NameValuePair>();
Iterator<String> it = mData.keySet().iterator();
while (it.hasNext()) {
String key = it.next();
nameValuePair.add(new BasicNameValuePair(key, mData.get(key)));
}
post.setEntity(new UrlEncodedFormEntity(nameValuePair, "UTF-8"));
HttpResponse response = client.execute(post);
StatusLine statusLine = response.getStatusLine();
if(statusLine.getStatusCode() == HttpURLConnection.HTTP_OK){
result = EntityUtils.toByteArray(response.getEntity());
str = new String(result, "UTF-8");
}
}
catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
catch (Exception e) {
}
return str;
}
/**
* on getting result
*/
#Override
protected void onPostExecute(String result) {
// something...
if (mListener != null) {
mListener.onResult(result)
}
}
}
Now.
You just write some lines like following:
HashMap<String, String> data = new HashMap<String, String>();
data.put("key1", "value1");
data.put("key2", "value2");
AsyncHttpPost asyncHttpPost = new AsyncHttpPost(data);
asyncHttpPost.setListener(new AsyncHttpPost.Listener(){
#Override
public void onResult(String result) {
// do something, using return value from network
}
});
asyncHttpPost.execute("http://example.com");
First i would not recommend do a Http request in a AsyncTask, you better try a Service instead. Going back to the issue on how to pass parameter into an AsyncTask when you declared it you can defined each Object class of the AsyncTask like this.
public AsyncTask <Params,Progress,Result> {
}
so in your task you should go like this
public MyTask extends<String,Void,Void>{
public Void doInBackground(String... params){//those Params are String because it's declared like that
}
}
To use it, it's quite simple
new MyTask().execute("param1","param2","param3")