Develop Reference

How to show an image for a specific time period?

In my application i need to decrypt the certain message format, to extract information like message id, timeout and so on.i need to show an corresponding image for the given id as well as to show it for the mentioned time period.
For that i have created one custom layout to show the image and other details. i'm using imageview for displaying the image. but dont know how to set timeiut for that?
Do anyone have idea on that?

You can easily use Handler to do that, like this
imageuser.setImageBitmap(bitmapObject);
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
imageuser.setImageBitmap(null);
}
}, 5000);
here, imageuser is your ImageView and replace 5000 with your specific time in miliseconds.

Just use it like whenever you want to show image just call your UI and start a thread for the given time you want to show the image and when the time complete just make that ui visibility gone,this is the logic try it in your own way.
thanks

After loading an activity, it sometimes works, sometimes not, why?

I have a bit of a problem I cannot solve, since it might a bug or something like that. I would like to make a chart with androidplot, and it works really good, but of course it needs some time to draw it (using hundreds of data), so I use a progress dialog to indicate the loading. But what happens is really weird.
I can define the appearance of the activity when it's loading and when it's loaded. When its loading I define a textview in the background setting its text to "loading" and if it is loaded, that textview contains lots of datas, text etc.
onCreate
{
Thread thread = new Thread(new Runnable() {
public void run() {
-------what needs to be appeared after its loaded ----
Textview -> 12,3245,456,78,789
}
----what is on the screen while the progressbar is on---
TextView -> loading..
}
But most of the time after the progress dialog disappears, nothing happens, the textview still says "loading" and rarely it loads the datas and makes the data appear and changes the textview. What I noticed that the more data I would like to appear the rarelier it stays at the loading phase. Of course everytime the loading progessbar appeers then disappears.
Any Suggestion? It is really weird because I use it in a tablayout and other tabs never do this, always make the data appear.
Thanks in advance!
UP: Okay, its always the first tab, whatever it contains, so the first tab is somehow wrong...

The Andoid UI toolkit is not thread-safe. So, you must not manipulate your UI
from a worker thread—you must do all manipulation to your user interface from
the UI thread. Thus, there are simply two rules to Android's single thread model:
1. Do not block the UI thread
2. Do not access the Android UI toolkit from outside the UI thread
read this for more information on how to access UI elements from outside.
edit::
use AsyncTask ::
onCreate
{
new myLoading().execute();
}
class myLoading extends AsyncTask<Void, Void, Void>
{
protected Void doInBackground(Void ... ) {
.......... do all the loading here .........
}
protected void onPostExecute(Void ) {
Textview -> 12,3245,456,78,789
}
}

I figured out some workaround. I dont have any clue about the solution, my only guess is the loading screen somehow overtake the arrival of all the data and so the chart cannot be drawn. or whatever...
I put a thread.sleep(1000) and now it works.

Displaying large tables without choking UI thread

I have a table with about 1k rows that I want to display. This task obviously chokes the UI thread, resulting in a black screen while the onCreate() builds the table.
I've solved this by using AsyncTask which builds the wanted TableLayout in the "doInBackground" function and display it on the "onPostExecute" function.
Question #1:
Is there any better practice that I'm not familiar with?
Question #2:
My (simplified) "doInBackground" function looks like this:
protected Void doInBackground(Void... v) {
tmpTableLayout = populateTable("");
return null;
}
And my (simplified) "onPostExecute" function looks like this:
protected void onPostExecute(Void v) {
TableLayout ct = (TableLayout)findViewById(R.id.RealTable);
ct.removeAllViews();
/* WHATS HERE? */
}
What should I write instead of the "WHATS HERE?" in the last line of code in order to display the content of "tmpTableLayout" in "ct" ?
Thanks in advance!

Are you sure you want to display it all in one go?
One approach would be to dynamically load in more lines as the user scrolls down. So have a scroll listener that checks if the user is approaching the end of the content that is displayed and therefore start an AsyncTask or a thread loading more content.
Example:
Android List Activity with dynamically loaded images form the web in android

I would probably use a ListView and CursorAdapter and let Android manage fetching the data for you. See the accepted answer here.

Weird updateViewLayout behaviour

I have a view (custom drawn) added with getWindowManager().addView() and later I'm modifiying the LayoutParameters of it (changing x & width) and call getWindowManager().updateViewLayout(). This works but I am getting two screen refreshes, first one only moves the whole thing according to the new x and later one scales it according to the new width. Any ideas about why is this happening even though I only call updateViewLayout just one time with the new layout parameters?
FYI: onDraw method of the custom drawn view mentioned here is also called only one time by the system during this process.

Try:
runOnUiThread(new Runnable() {
public void run() {
view.updateViewLayout();
}
});
http://developer.android.com/reference/android/app/Activity.html#runOnUiThread(java.lang.Runnable)
If it doesn't work, check this:
How to move a view in Android?
Are you doing this?

try to do :
view.post(new Runnable() {
public void run() {
view.updateViewLayout();
}
});

updateViewLayout is an a method that can be overriden by your custom ViewGroup and in this overrided method you can implement all what your want to change.
Maybe you do something wrong in it?
Or also maybe you have to implement this code in UiThread like in other questions. - In this case when you change your parameters asynchronously with first call of drawing function by system you method maybe can change only one parameter and on second call the second parameter will be also changed.

Android change in view depending upon a thread is over

I have created a Thread in onCreate(). It is running fine. Now I want to change something in view, when the thread is over. But if add it in the run() method, it is giving android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views. error. How to solve this problem?
Thread updateThread = new Thread() {
#Override
public void run() {
................
................
//this line is giving problem
loader.setVisibility(View.INVISIBLE);
}
};
updateThread.start();

You should use an AsyncTask http://developer.android.com/reference/android/os/AsyncTask.html instead of Thread, and do your loader.setVisibility(View.INVISIBLE) inside onPostExecute()

In Android, only the original UI-Thread can make changes to it's View. That's security policy. A solution that might be interesting for you, too is shown in this older thread.
Also have a look at Android's Handler-class (which is used in the Thread above).
But (as mentioned by zerpage), an AsyncTask might be the better way.