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Update the view in the MainActivity immediately from the server

I am createing checkbox list from an arrayList that I am getting from the Server, programmatically.The checkBox list is being created but I am facing problem that the value change in the MySQL table every minute. Regarding, I have to update the values of checkboxes list in the MainActivity. Is there any way in Android to update the values (getText) of the checkboxes in the MainActivity immediately like Ajax in JavaScript?
What I am trying to achieve, to rebuild the check box list in the MainActivity when value of the tables's record changes immediately. Which approach can I use to achieve that or the best what I can achieve, to remove the chechbox list element from the xml file and then send a new request to the Server periodically?
I appreciate any help.

Try to use this code in you onPostExecute()
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
new MyAsyncTask().execute();
}
}, 5*60*1000); // this is for a gap of 5 minutes

Maybe I understand what you want, update information from server continuous. Still using Handler, but by this way:
final Handler updateInfoHandler;
protected void onCreate(Bundle savedInstanceState) {
...
updateInfoHandler.post(new Runnable() {
#Override
public void run() {
//code update infomation
updateInfoHandler.postDelayed(this, 60000);//auto update info each 60s
}
});
}

How can I update the data on my listview using AsyncTask in android?

I am a newbie here, and I have searched online (and on stackoverflow) for the answer but I am still struggling to make it work.
What I am trying to do, is (1) update my list with fresh "posts" using an asyncronous task - thus allowing the user to continue using the app as I download new posts to their android.
I am struggling to get the updating task to work, and it could be tied to an obvious implementation problem (or not).
What I have is (1) A customized list (it allows "pull to refresh" - but as stated it is a problem that it is not refreshing any data at this point). (2) a custom AsyncTask that will theoretically populate more posts for the main list on the main screen.
Here is problem point in the list:
listView.setOnRefreshListener(new PullToRefreshListView.OnRefreshListener(listView) {
#Override
public void onRefresh() {
mylistAdapter.loadNewData(); //loads new data <-------------------
m_ptrlistView.postDelayed(new Runnable() {
#Override
public void run() {
m_ptrlistView.onRefreshComplete();
}
}, 2000);
////////////
Here is the function "loadNewData" in the adapter
public void loadNewData(PullToRefreshListView List){
//load new stuff
new AsyncFetchMore(list).execute();
// MANDATORY: Notify that the data has changed
notifyDataSetChanged();
return;
}
And... my asyncTask that is extended's implementation
#Override
protected Object doInBackground() {
try {
//simulating a long task
Thread.sleep(5000);
} catch (InterruptedException e) {
Log.d("Notes", "Thread failed to sleep");
}
//create dummy posts for testing
for ( int i = 12; i < 24; i++ ) {
Post pNewPost = new Post();
pNewPost.setText("POST # " + i);
m_alNewPosts.add(pNewPost);
}
return null;
}
///////////////////////////////
Perhaps I'm approaching it all wrong. I'm having doubts... But I just don't know what the right next step is and I am pretty lost here! Can you give me any tips?

It looks like you arent doint anything with results that are returned by your async task. But before you go to fix it, please consider using Loaders - they are asyncronous and made specifically for your purpouse - getting data for Fragment/Activity. Here is documentation for them. It looks like you might have a fair amount of refactoring to do if you want to implement them, but its well worth it - its the right way. hope this helps.

You are calling notifyDataSetChanged() right after you start your Async thread, which hasn't populated your data. Call notifyDataSetChanged() after the data has been updated. Check out the examples in ApiDemos in the samples directory of the SDK.

What may prevent the UI in android to be updated on time?

I'm developing an Android app that has to update it's UI depending on receiving and processing some server responses, I'm using runOnUiThread for that. I have like five activities in that app, all is working very well but one requires me to relaunch the Activity(like going to another one and then returning to it) or interacting with it in order to that update takes place, and that is the way i'm using with all the Activities including the infected one:
runOnUiThread(new Runnable() {
public void run() {
try {
response_received(response);
} catch (Exception e) {
e.printStackTrace(); // never catch any Exceptions
}
}
});
private static void response_received(JSONObject response) throws Exception{
try {
int volume_setted = response.getInt(volume);
Normal_Activity.volume_value.setText(String.valueOf(volume_setted)); // the Volume TextView updated efficiently
Infected_Activity.volume_value.setText(String.valueOf(volume_setted)); // has the problem mentioned above
} catch (JSONException ex) {
}
}
I'm pretty sure the problem is not in the TextView as all the Activity UI has this problem but i just posted an example.

Do not directly set values in a Activity from another Activity. If you want to pass data to Another activity always use Intents. check the below link
pass data from intent to an other intent
If you want to start another activity and get result back check the below link
http://developer.android.com/training/basics/intents/result.html

Multithreading data writing in SQLite [duplicate]

This question already has answers here:
How can I avoid concurrency problems when using SQLite on Android?
(10 answers)
Closed 9 years ago.
I'm confused a little bit when tried to establish a multithreading work with my SQLite db, so I have a service which periodically load a data from server and insert it in different db tables, also any user in any time can store his own data in db when pressed "save button" in app windows, so based on the rules that only one thread at time can write a data in db I'd'd like to make a thread-cooperation. At first I have created a singleton which have only one db instance, and all goes pretty good with my read-db methods, cause all threads can read data in the same time, but what about writing? I use a thread inside write-function, and don't give a start another until previous thread has finished it work.(also I do it for calls from ui thread when user press save button)
Question: All I want to do is consider two situations - first is when threads call's same function to write data then I used synchronized, second - when threads call different write functions I should use a lock, right? So now I came to decision, but is it correct and right to do like that?
Code (Updated):
// Sync method for processing 1st situation
public synchronized void addPoints(final ArrayList<Point> points, final OnDBOperationListener listener) {
if (listener != null) {
// Lock for others write-threads in 2nd situaton
synchronized (mWriteLock) {
while (mWriteWait) {
try {
mWriteLock.wait();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
mWriteWait = true;
try {
SQLiteDatabase db = getDatabase();
// write a data
listener.onSuccess();
} catch (Exception e) {
e.printStackTrace();
listener.onError();
} finally {
closeDatabase();
synchronized (mWriteLock) {
mWriteWait = false;
mWriteLock.notifyAll();
}
}
}
}
}

After a long search i finally found a gret answer for my broblem, so anyone who want to creat e multithreading acess to db should read this first What are the best practices for SQLite on Android?

How to load images from server properly?

I have a code below, this code works perfectly fine when you are trying to load one or two images. However, the problem is, when you have a lot of images in one Activity, all images must load first before you can get in. My question is, what is the best way to handle this images? I want the images to load one by one and not simultaneously. I want it to load just like the ListView made by Fedor "http://stackoverflow.com/questions/541966/android-how-do-i-do-a-lazy-load-of-images-in-listview" (Note: I'm not using a ListView, I just want my images to load like that). Please help me, I would really appreciate it a lot. Thanks in advance!
class ImageDownlaodThread extends Thread {
ImageDownloadMessageHandler imageDownloadMessageHandler;
String imageUrl;
#Override
public void run() {
Drawable drawable = LoadImageFromWebOperations(imageUrl);
Message message = imageDownloadMessageHandler.obtainMessage(1, drawable);
System.out.println("Message sent");
}
}
class ImageDownloadMessageHandler extends Handler {
View imageTextView;
}
#Override
public void handleMessage(Message message) {
progressBar.setVisibility(View.GONE);
imageTextView.setVisibility(View.VISIBLE);
}
}
Drawable LoadImageFromWebOperations(String url) {
Drawable d = null;
InputStream is = null;
try {
} catch (IOException e) {
e.printStackTrace();
}
return d;
}

Would this tutorial help [TUT] ImageView with Loading Spinner:
http://www.anddev.org/novice-tutorials-f8/imageview-with-loading-spinner-t49439.html
It basically show's a spinner until the image has loaded from the remote site :-)
You could strip the code to show a blank space / whatever you want till it loads.
If you don't want anything to happen till it all loads, you could have a count of how many images there are and then increment this each time an image has loaded.

IMO, AsyncTask is the easiest way to do this; in fact, it was basically built for this sort of task.
There's really too much to discuss in a StackOverflow answer. Just see Painless Threading to get started.