Develop Reference

How to show ProgressDialog across launching a new Activity?

Goal: Have a ProgressDialog which shows "Loading..." until next Activity is completely loaded and shown on screen.
Tried with ProgressDialog context and activity set to originating Activity. Also tried with getApplicationContext() and getParentContext(). Exceptions on the last two approaches. Need to do this as destination Activity is slow to render due to non-simple Layout file. (Cannot fix that right now due to organizational issues.) Turns out the destination Activity takes 1-2 seconds to OnCreate and then screen goes black for up to 5+ seconds then it paints. The rendering is just slow. Did review with Hierarchy Viewer and see lots of red balls but can't fix now.
Read up on some related but haven't found a fix. E.g. What's the difference between the various methods to get a Context?
E.g. both of these crash. Using the "this" of source Activity doesn't work either.
// Context parentContext = this.getParent().getBaseContext();
Context parentContext = this.getApplicationContext();
ProgressDialogMenuable theProgressDialog = new ProgressDialogMenuable(parentContext,this);
theProgressDialog.setTitle("yeeha");
theProgressDialog.setMessage("weewah");
theProgressDialog.setIndeterminate(true);
theProgressDialog.setCancelable(true);
theProgressDialog.show();
Also, oddly, nothing happens when I do this:
theProgressDialog.show();
ActivityHelper.changeActivity(this, v, InsMyHoldingsActivity.class, extraMap, -1, -1);
User clicks button to show next activity but the ProgressDialog conflicts with the Activity launch and nothing actually happens other than the button becoming yellow ontouch. Button below works. removing ProgressDialog creation and it works. No console messages logged. A little offputting to the developer for sure.

You can show a progress dialog like this -
Define this
private ProgressDialog pd = null;
in your activity class
Put this in your onCreate (Dont setContentView directly here)
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.pd = ProgressDialog.show(this, "Fancy App",
"Loading...Please wait...", true, false);
// Start a new thread that will download all the data
new IAmABackgroundTask().execute();
}
// Background heavy lifting
class IAmABackgroundTask extends
AsyncTask<String, Integer, Boolean> {
#Override
protected void onPreExecute() {
// showDialog(AUTHORIZING_DIALOG);
}
#Override
protected void onPostExecute(Boolean result) {
// Pass the result data back to the main activity
ActivityName.this.data = result;
if (ActivityName.this.pd != null) {
ActivityName.this.pd.dismiss();
}
setContentView(R.layout.main);
}
#Override
protected Boolean doInBackground(String... params) {
//Do all your slow tasks here but dont set anything on UI
//ALL ui activities on the main thread
return true;
}
}
Also go through this :http://developer.android.com/training/improving-layouts/index.html for optimizing layout performance.
Also Use Traceview to look for bottlenecks

There is two ways to
First approach To use Async Task
If you are doing heavy tasks eg loading data from server or parsing xml in that case use AsynTask<> If you want to call ActivityB from ActivityA then
*step-1*create a AsyncTask class. write all background tasks inside doBackground() method and after completion of task you want to call an activity that code write inside onPostExecute() post execute method
import android.content.Context;
import android.content.Intent;
import android.os.AsyncTask;
import android.view.View;
public class LoadingDataFromServer extends AsyncTask {
Context currentContext = null;
boolean isCancelled = false;
public LoadingDataFromServer(Context context) {
currentContext = context;
}
#Override
protected void onPreExecute() {
if (DashboardActivity.progressBarLayout != null) {
DashboardActivity.progressBarLayout.setVisibility(View.VISIBLE);
// Log.i(TAG,".....Now make progress bar visible.....");
}
super.onPreExecute();
}
#Override
protected Object doInBackground(Object... params) {
// do background processing
try {
// do background tasks eg sever communication
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Object result) {
// TODO Auto-generated method stub
// progressDialog.dismiss();
// call second Activity
Intent i = new Intent(currentContext, com.ActvityB.class);
super.onPostExecute(result);
}
#Override
protected void onCancelled() {
// TODO Auto-generated method stub
isCancelled = true;
super.onCancelled();
}
}
step-2 In the activity fro where you want to jump to new activity (eg in ActivityA) call the execute() of AsynTask
new LoadingDataFromServer(context).execute(null);
Second approach
First show progress dialog.
create a thread to do all background tasks. when the thread completes the task then cancel the progress dialog and call the next activity
or
when thread complets the task then call next activity pass this object (progress dialog) and inside that new activity dismiss this dialog.

Here is my code that can help.
In this, I'm only posting the first method of AsyncTask i.e onPreExecute.
User_AsyncTask extends AsyncTask:
public class User_AsyncTask extends AsyncTask<String, String, String>
{
String response = "";
#Override
protected void onPreExecute()
{
try
{
if (progressDialog != null)
progressDialog.cancel();
}
catch (Exception e)
{
}
progressDialog = ProgressDialog.show(DisplayDetails.this, "", "Please wait...", true, true);
progressDialog.setCancelable(false);
progressDialog.show();
}

Android progress dialog force showing

I have this lines of code:
1) m_ProgressDialog = ProgressDialog.show(m_Context, "", m_Context.getString(R.string.dictionary_loading));
2) //important code stuff: interact with db, change some textview values (= 2-3 seconds if i'm unlucky)
3) m_ProgressDialog.dismiss();
But what happens is that phase 2) happens before 1).. which is wrong. First UI freezes then dialog appears..
phase 2) is some code that interacts with DB, might also change some textViews..but since this might take a while i decided to show that progress dialog so that user would know that really important stuff is going on. I cant use Async for these operations since UI code & db code is mengled, it will only complicate my life
How can i force dialog to show at request ??.. to me it seams that code presented just adds it in a "To do list when i have some free time & i dont have time now" stack..

You are doing your work on the ui thread. You should use a separate thread for this to keep the UI (progress bar) responsive. Have a look at AsynchTask.

Do not use UiThread for background operations it lead to freeze of screen.You have to use separate thread like Asyc Task.
do like below
in
onCreate()
{
dialog.show();
new DownloadFilesTask().excute()
}
class DownloadFilesTask extends AsyncTask<Void,Void,Void>
{
protected Long doInBackground(URL... urls) {
//Background operation
}
return null;
}
protected void onProgressUpdate(Integer... progress) {
}
protected void onPostExecute(Long result) {
runOnUiThread(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
//Update you Ui here
dialog.dismiss();
}
});
}
}

For most of cases if you want to simply have 2 methods, ShowLoading() and HideLoading() just use this
public static void ShowLoading()
{
HideLoading();
myLoadingThread = new Thread(new ThreadStart(LoadingThread));
myLoadingThread.Start();
}
private static void LoadingThread()
{
Looper.Prepare();
myProgressDialog = new ProgressDialog(myActivity,
Resource.Style.AppTheme_Dialog);
myProgressDialog.SetMessage("Loading..."); // Or a #string...
myProgressDialog.SetIcon(Resource.Drawable.your_loading_icon);
myProgressDialog.SetProgressStyle(ProgressDialogStyle.Spinner);
myProgressDialog.SetCancelable(false);
myProgressDialog.Show();
Looper.Loop();
}
public static void HideLoading()
{
if (myProgressDialog != null)
{
myProgressDialog.Dismiss();
myProgressDialog = null;
}
if (myLoadingThread != null)
myLoadingThread.Abort();
}
Now I declare and explain the followings variables I used on my code sample, one of them is global, yes, if you don't like to use global vars, or you want to have 2 loading dialogs at a time (wtf...) look for another solution. This is just the simplest way, most friendly and free of weird code with nested methods, new classes and inheritance everywhere for such a simple thing:
private Thread myLoadingThread;
private ProgressDialog myProgressDialog;
// Some people will hate me for this, but just remember
// to call myActivity = this; on each OnStart() of your app
// and end with all your headaches
public Activity myActivity;

How to work with AsyncTask and threads?

The goal:
Using Google App Engine server and Android client, I'm trying to put on the Google map at the Android client Users overlays. Every 30 seconds I'm polling the server and getting Vector that contains users and adding it to the map.
Current status:
I'm dong all that using in one new thread, So after running the app I got:
weird behaviors(delayed overlays, multiple overlays) and after that crushed with ConcurrentModificationException.
After reading a bit i figured out that I need to work with AsyncTask.
Correct me if I'm wrong,But I understand that everything done in the Activity at at onCreate is "running" in UIhread so I need to put the "Logic" (All the Network handling) in doInBackground and all the UI Handling like putting overlays on the map in onPostExecute.
My Question are:
1) In the current status I'm doing:
new Thread()
{
#Override
public void run()
{
super.run();
while(true)
{
SystemClock.sleep(30000);
Vector responseFromServer = getUsersVectorFromServer();
putNewOnlineUserOnTheMap();
}
}
}.start();
What is the right way to convert this To AsyncTask?
Do I poll the server still using new thread in the doInBackground or there is right way to do this?
2) Is there a specific list of what counts as UI to put in onPostExecute or any concepts list?
In my case I guess that in need to put putNewOnlineUserOnTheMap() in onPostExecute.
Thanks.

Something similar to the following:
class UpdateTask extends AsyncTask<Void, Vector, Void>{
#Override
protected Void doInBackground(Void... params) {
// this is running in a background thread.
while (!isCancelled()) {
SystemClock.sleep(30000);
Vector responseFromServer = getUsersVectorFromServer();
// send the result back to the UI thread
// onProgressUpdate will be called then
publishProgress(responseFromServer);
}
return null;
}
#Override
protected void onProgressUpdate(Vector... values) {
// this is executed on the UI thread where we can safely touch UI stuff
putNewOnlineUserOnTheMap(values[0]);
}
}
You can't use the result of the task since the task is finished then. But you can use the progress publishing mechanism to get periodic results. If you use it like that and do the modification on the UI thread you should not get ConcurrentModificationException because you do the modifications on the one thread that can safely modify the UI.
One thing to note here: create new instances of your Vector in the background thread and then use it to update the UI. But don't touch the same object afterwards in the backgroundthread. That way you don't need any synchronization since after the background thread sends it away it is only the UI thread that touches it. (and you could use a simple ArrayList instead of a Vector)

AsyncTask uses generics and varargs.The parameters that are passed to the asyntask are . TypeOfVariableArgumentsParameters is passed into the doInBackground(), ProgressParam is used for progress information and ResultParam must be returned from doInBackground() and is passed to onPostExecute() as parameter.
example:--
protected class ParsingTask extends AsyncTask> {
private ProgressDialog loadingDialog = new ProgressDialog(JsonParserActivity.this);
protected void onPreExecute() {
loadingDialog.setMessage("loading app store..");
loadingDialog.show();
}
#Override
protected ArrayList<Items> doInBackground( Context... params ) {
// do ur process here.
return result;
}
if (!this.isCancelled()) {
}
return result;
}
#Override
protected void onProgressUpdate(String... s) {
super.onProgressUpdate(s);
Toast.makeText(getApplicationContext(), s[0], Toast.LENGTH_SHORT).show();
}
#Override
protected void onPostExecute( ArrayList<Items> response ) {
//if u r dealing with list view and adapters set the adapter here at the onPostExecute()
loadingDialog.dismiss();
}
#Override
protected void onCancelled() {
super.onCancelled();
Toast.makeText(getApplicationContext(), "The operation was cancelled", 1).show();
}
}

You can use AsyncTask like below. Hope this will help you..
Class YourClass{
void YourClass(){
NetworkTask nT = new NetworkTasK();
nT.execute();
}
}
protected class NetworkTask extends AsyncTask<Void, String, Boolean>
{
#Override
protected Boolean doInBackground(Void... params)
{
try
{
String response;
while(keepreceiving)
{
response = in.readLine();//Prog Counter stops here until getting i/p.
if(response != null)
yourFunctionForResponse(response);
}
}
catch (Exception ex)
{
}
return null;
}
private void yourFunctionForResponse(String response){
//things to do....
}
}
You may also try runOnUiThread(Runnable action) along with this to implement your work.

How to execute some code in Android UI thread async?

I'm new to Android development. I've be working on Swing and SWT for several years. Both Swing and SWT has a stratage to execute code in UI thread sync and async. The typical usage is doing some time-consume staff in one thread then display the result in UI thread async.
So my question is, is there similiar stratage in Android? Here is my code. Parameter runnable is some time-consume code. This method will display a waiting dialog during the execution then EXPECT to show a Toast after it is finished. But the Toast need to be show in UI thread. So how to do that?
public static void showWaitingDialog(final Activity parent, final Runnable runnable, String msg) {
if (StringUtils.isEmpty(msg)) {
msg = "processing...";
}
final ProgressDialog waitingDialog = ProgressDialog.show(parent, "Please Wait...", msg, true);
// execute in a new thread instead of UI thread
ThreadPoolUtil.execute(new Runnable() {
public void run() {
try {
// some time-consume operation
runnable.run();
} catch (Exception e) {
e.printStackTrace();
} finally {
waitingDialog.dismiss();
}
// TODO: How to display a Toast message here? execute some code in UI Thread.
}
});
}
And is there some words about Android UI system? Such as is it Thread-Safe, how thread works together and so on. Many Thanks!

There are several ways for doing that,
AsyncTask -
AsyncTask enables proper and easy use of the UI thread. This class
allows to perform background operations and publish results on the UI
thread without having to manipulate threads and/or handlers. Example for using AsyncTask
Service -
A Service is an application component representing either an
application's desire to perform a longer-running operation while not
interacting with the user or to supply functionality for other
applications to use. Example for Using Service.
IntentService -
IntentService is a base class for Services that handle asynchronous
requests (expressed as Intents) on demand. Clients send requests
through startService(Intent) calls; the service is started as needed,
handles each Intent in turn using a worker thread, and stops itself
when it runs out of work. Example for using IntentService.

You can use AsyncTask like this.
To call AsyncTask
new getAsynctask().execute("");
and here is the class for geting result.
class getAsynctask extends AsyncTask<String, Long, Integer> {
protected void onPreExecute() {
super.onPreExecute();
loading = ProgressDialog.show(Pass.this, null, "Please wait...");
}
protected Integer doInBackground(String... params) {
try {
// do your coding
return null;
} catch (Exception e) {
return null;
}
}
protected void onPostExecute(Integer result) {
super.onPostExecute(result);
try {
if (loading != null && loading.isShowing())
loading.dismiss();
} catch (Throwable t) {
Log.v("this is praki", "loading.dismiss() problem", t);
}
}
}

Whenever you are working with Separate thread which is not your UI thread the best way is to use Handler. Whenever you want to intimate user from your Thread, suppose a progress then send a message to Handler to so. Inside Handler you can handle message and write a code snippet to Change anything on UI. This is the preferred way for Android. see these link1 , link2 & link3

You use this AsynTask as a inner class of your activity. In do in background do the time consuming task you want to do and then in on postexecute you can show the text message.
call this from your main activity
initTask = new InitTask();
initTask.execute(this);
protected class InitTask extends AsyncTask<Context, Integer, String> {
#Override
protected String doInBackground(Context... params) {
// Do the time comsuming task here
return "COMPLETE!";
}
// -- gets called just before thread begins
#Override
protected void onPreExecute() {
super.onPreExecute();
}
// -- called from the publish progress
// -- notice that the datatype of the second param gets passed to this
// method
#Override
protected void onProgressUpdate(Integer... values) {
}
// -- called if the cancel button is pressed
#Override
protected void onCancelled() {
super.onCancelled();
}
// -- called as soon as doInBackground method completes
// -- notice that the third param gets passed to this method
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
// Show the toast message here
}
}

Use a handler:
static final int SHOW_TOAST = 0;
public static void showWaitingDialog(final Activity parent, final Runnable runnable, String msg) {
if (StringUtils.isEmpty(msg)) {
msg = "processing...";
}
final ProgressDialog waitingDialog = ProgressDialog.show(parent, "Please Wait...", msg, true);
// execute in a new thread instead of UI thread
ThreadPoolUtil.execute(new Runnable() {
public void run() {
try {
// some time-consume operation
runnable.run();
} catch (Exception e) {
e.printStackTrace();
} finally {
waitingDialog.dismiss();
}
handler.sendMessage(handler.obtainMessage(SHOW_TOAST));
}
});
}
public Handler handler = new Handler() {
#Override
public void handleMessage(Message msg) {
switch (msg.what) {
case SHOW_TOAST:
//Toast here
break;
}
}
};

The Painless threading article from the android developer resources provides different alternatives depending on the specific SDK version.

AsyncTask not locking main thread?

I'm using following code to fill a custom ListPreference dialog. Since the fill procedure takes a lot of time i want to show a progress dialog during the fill procedure.
My problem is that filler.execute() does not block onPrepareDialogBuilder and functions goes till the end before values are filled causing an exception... Any idea?
#Override
protected void onPrepareDialogBuilder(Builder builder) {
// Load data
if (this.getEntries()==null) {
FillerTask filler = new FillerTask();
filler.execute();
}
Log.d(TAG, "Filler finished");
super.onPrepareDialogBuilder(builder);
}
Here is Filltertask code, basically he looks for every activity with a MAIN Intent filling a list:
private class FillerTask extends AsyncTask<Void, Void, String[][]> {
private ProgressDialog dialog;
#Override
protected void onPreExecute() {
Log.d(TAG, "Dismiss dialog");
dialog = ProgressDialog.show(MyListPreference.this.getContext(), "", "Doing stuff...", true);
}
#Override
protected String[][] doInBackground(Void... params) {
return fill();
}
public String[][] fill() {
Log.d(TAG, "Fill started");
CREATE LISTS...
// Done
Log.d(TAG, "Fill done");
String[][] result = new String[][] {entryNames, entryValues};
return result;
}
#Override
protected void onPostExecute(String[][] result) {
Log.d(TAG, "Post execute");
MyListPreference.this.setEntries(result[0]);
MyListPreference.this.setEntryValues(result[1]);
dialog.dismiss();
}
}

My problem is that filler.execute() does not block onPrepareDialogBuilder and functions goes till the end before values are filled causing an exception... Any idea?
That is the entire point behind an AsyncTask. The "Async" in AsyncTask means asynchronous.
Use your AsyncTask to get your data. Then, in onPostExecute(), display the dialog.

Found the solution, best way to do this is override the onClick method and let the AsyncTask postExecute call the "super()", so click is not passed until content is loaded and during load progress bar is correctly displayed.

asyntask doesn't lock main thread, it just drops a message to message queue of main thread