I am having a progress dialog for a process. But i am taking a null pointer exception in my thread. But, when i remove the progress dialog. I am no longer taking an exception.
My code is as this
public class PlayedActivity extends ListActivity {
private PullToRefreshListView listView;
final Context context = this;
public Handler handler;
Runnable sendNumbers2;
List<On> playedOn;
DatabaseHandlerOn db;
private ProgressDialog m_ProgressDialog;
private ArrayList<On> m_results = null;
private PlayedOnAdapter m_adapter;
#SuppressLint({ "HandlerLeak", "HandlerLeak" })
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_playedonnumara);
db = new DatabaseHandlerOnNumara(getApplicationContext());
m_results = new ArrayList<OnNumara>();
this.m_adapter = new PlayedOnNumaraAdapter(this, R.layout.playedrowon, m_results);
this.setListAdapter(this.m_adapter);
sendNumbers2 = new Runnable() {
#Override
public void run() {
playedOn = db.getAllContacts();
for (On on : playedOn) {
m_results.add(on);
}
Collections.reverse(m_results);
//m_ProgressDialog.dismiss();
handler.sendEmptyMessage(0);
}
};
Thread thread = new Thread(sendNumbers2,"sendNumbers2");
thread.start();
/*m_ProgressDialog = ProgressDialog.show(PlayedOnNumaraActivity.this,
"",getString(R.string.PleaseWait), true);
m_ProgressDialog.setCancelable(true);
*/
handler = new Handler() {
#Override
public void handleMessage(Message msg) {
m_adapter.notifyDataSetChanged();
}
};
}
}
}
The code above is working and takes no exception when progress dialog codes are commented
Without your LogCat logs, I can only guess.
m_ProgressDialog is defined after you start your thread. Why? Define it before the thread is started.
Also, I would recommend an AsyncTask for this, instead. See Painless Threading for details on that.
Related
I try to close a ProgressDialog via Callback from Thread to fragment, but I don't know which reference I need to pass.
Some where in my Fragment I do the following:
c_thread_connectToDevice = new c_Thread_ConnectToDevice(UserSelectedDevice,
sFinalDonglePassword, getActivity());
if(UserSelectedDevice != null){
c_thread_connectToDevice.start();
mProgessDialog.setTitle(R.string.ProgressDialog_Fragmentsetpassword_Title);
mProgessDialog.setMessage(getResources().getString(R.string.ProgressDialog_Fragmentsetpassword_Message));
mProgessDialog.setIndeterminate(true);
mProgessDialog.show();
The Callback is:
public void dismissProgressDialog(){
mProgessDialog.dismiss();
if(!c_thread_connectToDevice.isbConnectionState()){
tv_Fragmentsetpassword_userhint.setTextColor(getResources().getColor(R.color.Mercedes_RED, null));
tv_Fragmentsetpassword_userhint.setText(R.string.tv_Fragmentsetpassword_ConnectionFailed);
}else {
tv_Fragmentsetpassword_userhint.setText(R.string.tv_Fragmentsetpassword_ConnectionSucces);
tv_Fragmentsetpassword_userhint.setTextColor(getResources().getColor(R.color.Mercedes_GREEN, null));
}
}
In my Thread the I use the following Code:
private WeakReference<Activity> weakReference;
...
dismissProgressDialog();
...
private void dismissProgressDialog(){
Activity activity = weakReference.get();
activity.dismissProgressDialog();
}
I know this could not work. But what is the right thing to pass?
What #Zach Bublil told me, brought me to this solution.
private Handler handler = new Handler(Looper.getMainLooper());
c_thread_connectToDevice = new c_Thread_ConnectToDevice(UserSelectedDevice, sFinalDonglePassword, c_Fragment_RoutineStartConnection_setpassword.this);
if(UserSelectedDevice != null){
c_thread_connectToDevice.start();
mProgessDialog = new ProgressDialog(getContext());
mProgessDialog.setTitle(R.string.ProgressDialog_Fragmentsetpassword_Title);
mProgessDialog.setMessage(getResources().getString(R.string.ProgressDialog_Fragmentsetpassword_Message));
mProgessDialog.setIndeterminate(true);
mProgessDialog.show();
CallBack
public void dismissProgressDialog(){
mProgessDialog.dismiss();
handler.post(new Runnable() {
#Override
public void run() {
if(!c_thread_connectToDevice.isbConnectionState()){
tv_Fragmentsetpassword_userhint.setTextColor(getResources().getColor(R.color.Mercedes_RED, null));
tv_Fragmentsetpassword_userhint.setText(R.string.tv_Fragmentsetpassword_ConnectionFailed);
}else {
tv_Fragmentsetpassword_userhint.setText(R.string.tv_Fragmentsetpassword_ConnectionSucces);
tv_Fragmentsetpassword_userhint.setTextColor(getResources().getColor(R.color.Mercedes_GREEN, null));
}
}
});
InsideFragment
private c_Thread_ConnectedToBluetoothDevice c_thread_connectedToBluetoothDevice;
public c_Thread_ConnectToDevice(BluetoothDevice device, String sFinalDonglePassword, c_Fragment_RoutineStartConnection_setpassword reference) {
this.mBluetoothDevice = device;
this.sFinalDonglePassword =sFinalDonglePassword;
this.reference = reference;
}
...
dismissProgressDialog();
...
private void dismissProgressDialog(){
reference.dismissProgressDialog();
}
What is difficult for me to understand is, why I need to run the callback Text editions on mainthread. If I don't do that there is an exception to "Only the original thread creating the view..." but this is maybe caused by
tools:context=".c_RoutineStartConnection"
which I used in the Fragment layout for better usability.
I'm trying to make multithreading but I've got this stacktrace on few smartphones (SGS2) :
java.lang.ExceptionInInitializerError
at com.android.bordeaux.code.model.AnnouncersContainer.setLoudArrayFromJSON_online(AnnouncersContainer.java:68)
at com.android.bordeaux.code.SplashscreenActivity_Second$1.run(SplashscreenActivity_Second.java:55)
Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
at android.os.Handler.<init>(Handler.java:121)
at android.os.AsyncTask$InternalHandler.<init>(AsyncTask.java:421)
at android.os.AsyncTask$InternalHandler.<init>(AsyncTask.java:421)
at android.os.AsyncTask.<clinit>(AsyncTask.java:152)
... 2 more
Here is my main activity (splashscreen) wich is making wait during few seconds in order to wait my asynctask finish:
public class SplashscreenActivity_Second extends Activity
{
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.splashscreen_second);
// thread
Thread splashThread = new Thread()
{
#Override
public void run()
{
try
{
int waited = 0;
if (isInternetOn())
{
// Here I'm making my asynctask !!
AnnouncersContainer.setLoudArrayFromJSON_online(getApplicationContext());
while (waited < 5000)
{
sleep(50);
waited += 40;
}
}
else
{
AnnouncersContainer.setLoudArrayFromXML_local(getApplicationContext());
while(waited < 5000)
{
sleep(50);
waited += 60;
}
}
}
catch( InterruptedException e )
{
e.printStackTrace();
}
finally
{
Intent intent_to_tabhost = new Intent(SplashscreenActivity_Second.this, MyTabActivity.class);
startActivity(intent_to_tabhost);
finish();
}
}
};
splashThread.start();
}
}
Here is my asynctask :
public class DownloadAnnouncers extends AsyncTask<Void, Integer, Boolean>
{
public static Boolean loadFinished = false;
//JSON variables..
private static String url = null;
Context context;
public DownloadAnnouncers(Context context)
{
this.context = context;
}
#Override
protected void onPreExecute()
{
super.onPreExecute();
}
protected Boolean doInBackground(Void... params)
{
// fine retrieving all my JSON data in a global array..
}
#Override
protected void onPostExecute(Boolean downloadedArray)
{
super.onPostExecute(downloadedArray);
}
}
I know the problem is that I'm making multithreading in the UI but someone can tell me how to delete my looping thread and replacing it just with onPostExecute() method of my Asynctask ?? (it could be better to wait for asynctask finishes rather than making wait..)
Or may be help me to correct this bug with multithreading..
EDIT :
my asynctask :
public class DownloadAnnouncers extends AsyncTask<Void, Integer, Boolean>
{
public static Boolean loadFinished = false;
//JSON variables..
private static String url = null;
Context context;
public DownloadAnnouncers(Context context)
{
this.context = context;
}
#Override
protected void onPreExecute()
{
super.onPreExecute();
}
protected Boolean doInBackground(Void... params)
{
// fine retrieving all my JSON data in a global array..
}
#Override
protected void onPostExecute(Boolean downloadedArray)
{
super.onPostExecute(downloadedArray);
Intent intent_to_tabhost = new Intent(context, MyTabActivity.class);
intent_to_tabhost.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(intent_to_tabhost);
}
}
But now if I press cancel button I'm returning to my splashscreen activity.. and I cannot do ctx.finish() in onPostExecute method..
You can't create a Handler inside a Thread that has not called Looper.prepare(), just as your Error message says:
Can't create handler inside thread that has not called Looper.prepare()
The Handler is created within the AsyncTask, so it's not something you might see at first.
If you want to keep your code as it is you would fix it by moving the creation of the AsyncTask to outside your custom Thread.
However, there is no need for you to create the thread, you can just create your AsyncTask in the ui thread (It will run on it's own thread so it won't lock your phone while working), and perform any action you want after the task is complete in the onPostExecute-method.
class ExampleAsync extends AsyncTask<Void, Integer, Boolean>
{
public static Boolean loadFinished = false;
//JSON variables..
private static String url = null;
Context context;
public DownloadAnnouncers(Context context){
this.context = context;
}
protected Boolean doInBackground(Void... params){
// fine retrieving all my JSON data in a global array..
}
#Override
protected void onPostExecute(Boolean downloadedArray){
Intent intent_to_tabhost = new Intent(context, MyTabActivity.class);
startActivity(intent_to_tabhost);
}
}
And in your Activity:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.splashscreen_second);
AsyncTask myTask = new ExampleAsync(this);
myTask.execute();
}
Instead of waiting for the asyncTask , use the onPostExecute , which is called on the UI thread only after the task has finished.
You should also cancel the task if the activity was destroyed (for example if the user has pressed the back button while the splash screen is shown) .
In my Main Activity, I have a Thread that is doing alot of stuff, including adding some records to a database. In my second activity, which inherit from the Main Activity, I want to do a query to my database. But I need to check if the first thread in the Main Activity is finished, what I've done so far is:
public class History extends Main {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(!(MainThread.isAlive())) {
getFromDatabase();
}
}
}
This is my getFromDatabase() method
pd = ProgressDialog.show(this, "Please Wait",
"Getting cases from database", false);
Thread t = new Thread(this);
t.start();
which will call this run method:
#Override
public void run() {
ArrayList<Case> c = db1.getAllCases();
Message msg = handler.obtainMessage();
msg.obj = c;
handler.sendMessage(msg);
}
private Handler handler = new Handler() {
#SuppressWarnings("unchecked")
#Override
public void handleMessage(Message m) {
pd.dismiss();
list = (ArrayList<Case>) m.obj;
tempList = getCaseNumberToTempList(list);
tempCaseList = createTempList(list);
lv.setAdapter(new CustomAdapter(History.this, list));
lv.setTextFilterEnabled(true);
}
};
But if I do so, the following line of code will crash my application, it will give a NullPointerException:
if(!(MainThread.isAlive())) {
getFromDatabase();
}
How can I be sure that that the first thread is finished with all the work before I query the database from my history activity?
You can make the Thread in the getFromDatabase() method a static class level variable, write a static get method for it in your Activity, and check for isAlive() in your child Activity.
How about simply using a semaphore variable that you modify from the thread once it has reached a certain state?
During onCreate(), I'm downloading resources from the web, which takes time. I'd like to display a message on the screen to advise the user. I tried toast, but nothing shows up. Is there another way to print something to the screen?
i think onCreate() work like a constructor for a class and you can not load any visual when it is not finished yet.
so i advice you to use another activity with your message and then call your activity in it.
You have to create a splash screen , that's the way it's called.
It's a mediator Activity that is handling such actions.
Example:
public class SplashScreen extends BaseActivity {
public ProgressDialog ProgressBar = null;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
HideTitle();
setContentView(R.layout.splash);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
if (!IsConnected()) {
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
public void run() {
finish();
}
}, 4000);
} else {
ProgressBar = ProgressDialog.show(this, "", "Loading...", false, false);
SplashScreenDelay splashScreenDelay = new SplashScreenDelay(this, this);
splashScreenDelay.execute(10);
}
}
here is the class that does the loading and after that sends to the main
public class SplashScreenDelay extends AsyncTask<Integer, Integer, List<RssItem>> {
private Context _context;
private SplashScreen _activity;
public SplashScreenDelay(SplashScreen activity, Context context) {
_context = context;
_activity = activity;
}
#Override
protected List<RssItem> doInBackground(Integer... params) {
return RssParsingService.getListOfItems();
}
#Override
protected void onPostExecute(List<RssItem> result) {
Intent intent = new Intent(_context, Viewport.class);
_context.startActivity(intent);
if (_activity.ProgressBar != null) {
_activity.ProgressBar.dismiss();
}
}
}
I have spent last couple of hours searching for answers here but nothing seems to make it clear for me.
Here's my problem: I have a simple app with a main menu. One of the options retrieves a list of comments from a PHP server, updates the database and then displays a ListView.
Everything functions properly inside. Now, every time I press back and then start the activity again, a new thread is started. I managed to get to more than 50+ waiting threads. I'm using the DDMS tab from Eclipse to monitor the treads.
If I try to call Looper.getLooper().quit() or Looper.myLooper().quit() I get an error saying "main thread not allowed to quit".
What am I doing wrong and where/how should I be stopping the thread?
Here's the code:
public class RequestActivity extends Activity {
ProgressDialog pDialog;
DatabaseHelper db;
int userId;
myCursorAdapter adapter;
Thread runner = null;
ListView list;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
userId = myApplication.getInstance().getSession().getUserId();
setContentView(R.layout.request_list);
db = new myProvider.DatabaseHelper(this);
Cursor cursor = db.getRequests(userId);
startManagingCursor(cursor);
adapter = new myCursorAdapter(RequestActivity.this, cursor);
list = (ListView) findViewById(R.id.list);
list.setVisibility(View.INVISIBLE);
list.setAdapter(adapter);
pDialog = ProgressDialog.show(RequestActivity.this, "", "Loading ...", true, false);
runner = new Thread() {
Handler handler = new Handler() {
#Override
public void handleMessage(Message msg) {
adapter.getCursor().requery();
}
};
public void run() {
Looper.prepare();
// ... setup HttpGet
try {
// ... get HTTP GET response
if (response != null) {
// ... update database
handler.sendEmptyMessage(0);
}
} catch(Exception e) {
// .. log exception
}
Looper.loop();
}
};
runner.start();
}
private static class ViewHolder {
// .. view objects
}
private class myCursorAdapter extends CursorAdapter {
private LayoutInflater inflater;
public myCursorAdapter(Context context, Cursor c) {
super(context, c);
inflater = LayoutInflater.from(context);
}
#Override
public void bindView(View view, Context context, Cursor cursor) {
// .. bind data
if (cursor.isLast()) {
pDialog.dismiss();
list.setVisibility(View.VISIBLE);
}
}
#Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
View view = inflater.inflate(R.layout.request_list_item, parent, false);
ViewHolder holder = new ViewHolder();
// .. set holder View objects
view.setTag(holder);
return view;
}
}
}
You're calling quit() on your main thread's Looper. Not the thread's Looper.
You can try this. Create a separate private inner-class that extends Thread. In the run() method, do a call to Looper.myLooper() to save the thread's Looper instance in the class. Then have a quitting method that calls quit on that looper.
Example:
private class LooperThread extends Thread{
private Looper threadLooper;
#Override
public void run(){
Looper.prepare();
threadLooper = Looper.myLooper();
Looper.loop();
}
public void stopLooper(){
if(threadLooper != null)
threadLooper.quit();
}
}
On your onDestroy method do you make any calls to stop the thread?
public void onDestroy()
{
Thread moribund = runner;
runner = null
moribund.interrupt();
}
You are calling the Looper.quit() method within your main (UI) thread, which is not allowed. Try posting a Runnable to the handler inside your thread that calls Looper.quit(). This will cause the Looper within the thread context to quit.