Develop Reference

ProgressBar not showing, android

Here is my code:
automaticCountryButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
progressBar.setVisibility(View.VISIBLE);
if (ContextCompat.checkSelfPermission(HomeActivity.this,
Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED){
setUpLocationPermission();
return;
}
Log.d(TAG, String.valueOf(gps.canGetLocation()));
Log.d(TAG, String.valueOf(gps.getLocation()));
Log.d(TAG, String.valueOf(gps.getLatitude()));
Log.d(TAG, String.valueOf(gps.getLongitude()));
Geocoder myLocation = new Geocoder(HomeActivity.this);
try
{
myList = myLocation.getFromLocation(gps.getLatitude(), gps.getLongitude(), 1);
}
catch (Exception e)
{
Log.d(TAG, "unable");
e.printStackTrace();
}
if(myList != null) {
try {
String country = myList.get(0).getCountryName();
Log.d(TAG, country);
findCountryInArrayList(country);
}
catch (Exception e)
{
Toast.makeText(HomeActivity.this, "Didn't manage to automatically detect location.", Toast.LENGTH_SHORT).show();
e.printStackTrace();
}
}
}
});
}
I want that immediately after the view is clicked the progressbar will become visible. However, it donesn't become visable until all the code is finished, which is against the whole point.
WHy is this not happening right at the beginning of the click? I have put progressBar.setVisibility(View.VISIBLE) at the top, why is it only executed after all the code is done, which sometimes takes a few seconds.
Thanks very much.

This is because you are trying to do your work on the UI thread - the UI will not actually be updated at all until this method finishes.
Try changing up your call to this:
public void onClick(View view) {
progressBar.setVisibility(View.VISIBLE);
progressBar.post( new Runnable() {
public void run() {
// long running code that has UI interactions
}
});
}
This will show the view immediately, and submit the runnable - long running task - to the message queue; this task will be run on a background thread that can still manipulate the UI, but will not cause it to hang.

Android Simon sequence in UIThread

I am very new in Android, as a project, am doing a simon says game, and I'm having some problems representing the sequence to follow.
I tried to use a normal thread to make it follow a line (for example, the first button is lighten during X seconds, then turns off, then the yellow one....), but it didn't make it, because only the threads that created the view hierarchy can manipulate that view (in this case was the UI thread). So I had to load all the method in that thread with runOnUiThread, and at that point it worked almost perfect, because now the sequence is shown up but the frames don't. The Log tells me:
I/Choreographer: Skipped 116 frames! The application may be doing too much work on its main thread.
I have been looking for everywhere and I don't find alternatives for simulate the sequence. I leave here the code of the method.
public void createSequence(){
new Thread() {
public void run() {
runOnUiThread(new Runnable() {
#Override
public void run() {
sequence.clear();
for(byte i=0;i<rounds;i++){
add=r.nextInt((4 - 1) + 1) + 1;
if (add == 1) {
btn1.setBackgroundResource(R.drawable.button1_pressed);
try {
Log.i("Waiting for 1.","Waiting for 1.");
Thread.sleep(time);
btn1.setBackgroundResource(R.drawable.button1);
} catch (InterruptedException e) {
e.printStackTrace();
}
Log.i("Value:", "1.");
} else if (add == 2) {
btn2.setBackgroundResource(R.drawable.button2_pressed);
try {
Log.i("Waiting for 2.","Waiting for 2.");
Thread.sleep(time);
btn2.setBackgroundResource(R.drawable.button2);
} catch (InterruptedException e) {
e.printStackTrace();
}
Log.i("Value:", "2.");
} else if (add == 3) {
btn3.setBackgroundResource(R.color.colorpressedbutton3);
try {
Log.i("Waiting for 3.","Waiting for 3.");
Thread.sleep(time);
btn3.setBackgroundResource(R.drawable.button3);
} catch (InterruptedException e) {
e.printStackTrace();
}
Log.i("Value:", "3.");
} else {
btn4.setBackgroundResource(R.color.colorpressedbutton4);
try {
Log.i("Waiting for 4.","Waiting for 4.");
Thread.sleep(time);
btn4.setBackgroundResource(R.drawable.button4);
} catch (InterruptedException e) {
e.printStackTrace();
}
Log.i("Value:", "4.");
}
sequence.add(add);
}
}
});
}
}.start();
}

You almost got it.
You need to implement the timing logic in a separate thread, but the update (UI) logic on the UI thread.
Something like this:
void setState(final Button b, final int state) {
this.runOnUiThread(new Runnable() {
#Override
public void run() {
b.setBackgroundResource(state);
}
});
}
void runSequence() {
new Thread() {new Runnable() {
#Override
public void run() {
sequence.clear();
for(byte i=0;i<rounds;i++){
add=r.nextInt((4 - 1) + 1) + 1;
if (add == 1) {
setState(btn1,R.drawable.button1_pressed);
try {
Log.i("Waiting for 1.","Waiting for 1.");
Thread.sleep(time);
setState(btn1, R.drawable.button1);
} catch (InterruptedException e) {
e.printStackTrace();
}
Log.i("Value:", "1.");
} else if (add == 2) {
....
}
}).start();
}

Wait for thread to finish and then move to next position

i am trying to display a Toast on the screen and when Toast fades off then move to the next question. I have tried with Thread but cannot seem to manage.
My code:
next.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (getUserSelection()){
position = position + 3;
if (position < questionsArray.size()) {
curName = questionsArray.get(position).getName();
curArray = questionsArray.get(position).getAnswers();
curIscorrect = questionsArray.get(position).getIscorrect();
setupQuestionView(curName, curArray, curIscorrect);
} else {
StringGenerator.showToast(QuestionsActivity.this, "Your score : " + score + "/" + (questionsArray.size() / 3));
}
}else {
StringGenerator.showToast(QuestionsActivity.this, getString(R.string.noanswerselected));
}
}
});
and the getUserSelectionMethod:
private boolean getUserSelection() {
correct = (RadioButton)findViewById(group.getCheckedRadioButtonId());
if (correct == null){
return false;
}else {
correctAnswerText = correct.getText().toString();
if (map.get(correctAnswerText).equals(Constants.CORRECTANSWER)) {
score++;
setCorrectMessage();
return true;
} else {
setWrongMessage();
return true;
}
}
}
private void setCorrectMessage() {
correctToast = new Toast(QuestionsActivity.this);
correctToastView = getLayoutInflater().inflate(R.layout.correct, (ViewGroup) findViewById(R.id.correctRootLayout));
correctText = (TextView)correctToastView.findViewById(R.id.correctTextView);
correctText.setText(getString(R.string.correctAnswer));
correctToast.setDuration(Toast.LENGTH_SHORT);
correctToast.setView(correctToastView);
correctToast.show();
correctThread = new Thread(new Runnable() {
#Override
public void run() {
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
correctToast.cancel();
}
});
correctThread.start();
}
private void setWrongMessage() {
wrongToast = new Toast(QuestionsActivity.this);
wrongToastView = getLayoutInflater().inflate(R.layout.wrong, (ViewGroup) findViewById(R.id.wrongRootLayout));
wrongText = (TextView)wrongToastView.findViewById(R.id.wrongTextView);
wrongText.setText(getString(R.string.wrongAnswer));
wrongToast.setDuration(Toast.LENGTH_SHORT);
wrongToast.setView(wrongToastView);
wrongToast.show();
wrongThread = new Thread(new Runnable() {
#Override
public void run() {
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
wrongToast.cancel();
}
});
wrongThread.start();
}
Any suggestion on how to do this?

You can determine the toast visibility:
toast.getView().getWindowToken()
If the result is null, than your toast isn't visible anymore, and than you can run any code you want.

as stated in this answer you can start a thread that waits the duration of the Toast:
Thread thread = new Thread(){
#Override
public void run() {
try {
Thread.sleep(3500); // 3.5seconds!
// Do the stuff you want to be done after the Toast disappeared
} catch (InterruptedException e) {
e.printStackTrace();
}
}
};
Toast.LENGTH_SHORT and Toast.LENGTH_LONG are only flags so you have to either hard code the duration or keep them in a constant. The durations are 3.5s (long) and 2s (short).
If you want to manipulate some of your views, you cannot do this in another thread than the "main" UI thread. So you have to implement a kind of callback/polling mechanism to get notified when the SleepThread has finished.
Check this answer to read about a couple of ways to do this. Probably the easiest of them to understand and implement is this:
After you started your Thread you can check if it is still alive and running by calling thread.isAlive(). In this way you can do a while loop that runs while the thread is running:
// start your thread
while(thread.isAlive()){}
// continue the work. The other thread has finished.
Please note that this is NOT the most elegant way to do this! Check the other possibilities in the answer I've mentioned above for more elegant solutions (especially the last one with the listeners is very interesting and worth reading!)

That's because the Thread class is purely executed in the background and you need to manipulate the view in the Main thread. To solve your issue just replace the Thread with AsynTask.
AsyncTask<Void,Void,Void> a = new AsyncTask<Void, Void, Void>() {
#Override
protected Void doInBackground(Void... params) {
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
correctToast.cancel();
}
};
a.execute();
If you look at my code you can see my onPostExecute, this method is called in the Main Thread.

My Error was because i was trying to acess UI Elements through another Thread so modifying the code like this:
Thread thread = new Thread(new Runnable() {
#Override
public void run() {
try {
Thread.sleep(500);
QuestionsActivity.this.runOnUiThread(new Runnable() {
#Override
public void run() {
moveToNextQuestion();
}
});
} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
thread.start();
did the trick. I hope my answer helps someone!!!

how to force the AsyncTask to wait

i want the AsyncTask to wait till it finishes. so i wrote the below code and i used .get() method as follows and as shown below in the code
mATDisableBT = new ATDisableBT();
but at run time the .get() doesnt force ATDisableBT to wait, becuase in the logcat i receive mixed order of messages issued from ATDisableBT and ATEnableBT
which means .get() on ATDisableBT did not force it to wait
how to force the AsyncTask to wait
code:
//preparatory step 1
if (this.mBTAdapter.isEnabled()) {
mATDisableBT = new ATDisableBT();
try {
mATDisableBT.execute().get();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
//enable BT.
this.mATEnableBT = new ATEnableBT();
this.mATEnableBT.execute();

You can do this way:
doInBackground of AsyncTask
#Override
protected Void doInBackground(String... params) {
Log.i("doInBackground", "1");
synchronized (this) {
try {
mAsyncTask.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
Log.i("doInBackground", "2");
return null;
}
Outside this function from where you have to nstrong textotify AsyncTask to release from wait state:
new CountDownTimer(2000, 2000) {
#Override
public void onTick(long l) {
}
#Override
public void onFinish() {
synchronized (mAsyncTask) {
mAsyncTask.notify();
}
}
}.start();
Here I have notified AsyncTask by CountDownTimer after 2 seconds.
Hope this will help you.

You should execute AsyncTask on UI thread, so using get() - which will block it makes no sense - it might get you ANR error.
If you are on HONEYCOMB and up, then AsyncTasks are executed on single executor thread, serially - so your mATEnableBT should get executed after mATDisableBT. For more see here:
http://developer.android.com/reference/android/os/AsyncTask.html#execute(Params...)
You might also switch from AsyncTask to Executors. AsyncTask is implemented using executors. By creating single threaded executor you make sure tasks will get executed serially:
ExecutorService executor = Executors.newSingleThreadExecutor();
//...
executor.submit(new Runnable() {
#Override
public void run() {
// your mATDisableBT code
}
});
executor.submit(new Runnable() {
#Override
public void run() {
// your mATEnableBT code
}
});

Android Thread Join

in my code I have a code inside a thread that first tries to update something from Database and if the update is not successful then an insert is tried. My problem is that this code is called twice (it's not ok I know but let's ignore this for now) and because of this the insert is called twice because the update is not finished (at least this is what I think). I searched on google I thought to use thread.join(). My question is if it's ok to use thread.join() in my case.
Thanks
public void persistChangesToDatabase() {
final Thread backThread = new Thread(new Runnable() {
#Override
public void run() {
try {
openDataBase();
<-- SOME CODE -->
//First, an UPDATE is tried
int rowsAffected = updateTable();
// If update fails an INSERT is tried
if (rowsAffected == 0) {
//Insert
insert();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
});
backThread.start();
try {
backThread.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
}