Develop Reference

How to wait button clicks for a while in android

I am developing an application for blinds.
I have 4 screen sized buttons (overlapped). Every step of program one button will be clickable and every button has more than one job.
My program starts with a voice (Android TTS engine). Like "please touch screen to do x". After this step I want to wait 3 seconds for button click, if button is not clicked vocalize "please touch screen to do y" and wait 3 seconds again for job y. (x and y is first button's jobs).
Button should do one of them according to touching screen. But how can I wait 3 seconds for button click and continue to vocalize next options and wait 3 seconds again.
If first button is clicked, it will disappear-button 2 will be clickable- and TTS engine will start to vocalize second buttons options. Application will be work like this but I am stuck in waiting button clicks part.

I would advise you to use android.os.Handler instead. In your case you could do something like this:
public void onCreate() {
this.handler = new Handler()
playTheVoiceOfThingX()
viewToTap.setOnClickListener(new OnClickListener(){
#Override
public void onClick(View v) {
doThingX();
}
});
handler.postDelayed(new PrepareThingYTask(), 3000);
}
class PrepareThingYTask() implements Runnable {
viewToTap.setOnClickListener(new OnClickListener(){
#Override
public void onClick() {
doThingY();
}
});
handler.postDelayed(new PrepareThingZTask(), 3000);
}
class PrepareThingZTask() implements Runnable {
....
}
A good reminder, the runnable executed by the handler can be executed in UIThread, so no heavy work on it, or create a different looper to run it.
Regards

You could solve your problem with busy wait.
So after you first vocalized "please touch screen..." you would start a background thread which waits for a specific amount of time, like so:
new Thread(new Runnable() {
public void run() {
Thread.sleep(3000);
runOnUiThread(new Runnable() {
#Override
public void run() {
//vocalize
}
});
}
}).start();
As you can see, from within the thread a new runnable is started after 3 seconds which again runs on the UI Thread. This, because I think I remember that you should make such sound-things (depending on your method of how to play the file / sound) only from the UI Thread.
However, this is just an idea and I could not test-run my code!
But I hope I inspired you!
Regards
Me

Small android animation delay issue

I just want to call a function after every 3secs on click of a button
What is going wrong here-
galleryBtn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
final Handler handler = new Handler();
for(int i = 0;i<3;i++){
handler.postDelayed(new Runnable() {
#Override
public void run() {
// Do something after 5s = 5000ms
viewAnimator.showNext();
}
}, 3000);
}
}
});

You don't actually say what goes wrong but I'll take a wild guess that nothing happens (i.e. no animations) and the reason for that is probably that your Handler is being GC'd long before it gets to handle anything. Try keeping moving 'handlers' scope from local variable to class member.
(Also note that, even when it works, all 3 of your functions will run at more or less the same time. If you want them to run 3 seconds apart you should change the '3000' to 'i*3000'.)

Automatically start execution upon activity launch

I'm working on an app that synchronizes some graphic UI events with an audio track. Right now you need to press a button to set everything in motion, after onCreate exits. I'm trying to add functionality to make the audio/graphical interaction start 10 seconds after everything is laid out.
My first thought is, at the end of onCreate, to make the UI thread sleep for 10000 miliseconds using the solution here and then to call button.onClick(). That seems like really bad practice to me, though, and nothing came of trying it anyway. Is there a good way to implement this autostart feature?

Never ever put sleep/delay on UI-thread. Instead, use Handler and its postDelayed method to get it done inside onCreate, onStart or onResume of your Activity. For example:
#Override
protected void onResume() {
super.onResume();
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
//do whatever you want here
}
}, 10000L); //the runnable is executed on UI-thread after 10 seconds of delay
}

Handler handler=new Handler();
Runnable notification = new Runnable()
{
#Override
public void run()
{
//post your code............
}
};
handler.postDelayed(notification,10000);

Yes, putting the UI thread to sleep isnt a good idea.
Try this
private final ScheduledExecutorService worker = Executors.newSingleThreadScheduledExecutor();
worker.schedule(task, 10, TimeUnit.SECONDS);

Implementing a while loop in android

I can't understand the implementation of a while loop in android.
Whenever I implement a while loop inside the onCreate() bundle, (code shown below)
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.main);
TextView=(TextView)findViewById(R.id.TextView);
while (testByte == 0)
updateAuto();
}
nothing boots up, and the program enters a "hanging" state after a while and I can't understand why. Testbyte is as follows:
byte testByte == 0;
and updateAuto() is supposed to update the code per 1 second and display inside the textView portion. I've been using setText inside updateAuto() as shown below and everything works fine, but once i implement the while loop all i see is a black screen and then an option to force close after a few seconds due to it "not responding".
TextView.setText(updateWords);
I've changed it to a button format (meaning i have to click on the button to update itself for now), but i want it to update itself instead of manually clicking it.
Am i implementing the while loop in a wrong way?
I've also tried calling the while loop in a seperate function but it still gives me the black screen of nothingness.
I've been reading something about a Handler service... what does it do? Can the Handler service update my TextView in a safer or memory efficient way?
Many thanks if anyone would give some pointers on what i should do on this.

Brace yourself. And try to follow closely, this will be invaluable as a dev.
While loops really should only be implemented in a separate Thread. A separate thread is like a second process running in your app. The reason why it force closed is because you ran the loop in the UI thread, making the UI unable to do anything except for going through that loop. You have to place that loop into the second Thread so the UI Thread can be free to run. When threading, you can't update the GUI unless you are in the UI Thread. Here is how it would be done in this case.
First, you create a Runnable, which will contain the code that loops in it's run method. In that Runnable, you will have to make a second Runnable that posts to the UI thread. For example:
TextView myTextView = (TextView) findViewById(R.id.myTextView); //grab your tv
Runnable myRunnable = new Runnable() {
#Override
public void run() {
while (testByte == 0) {
Thread.sleep(1000); // Waits for 1 second (1000 milliseconds)
String updateWords = updateAuto(); // make updateAuto() return a string
myTextView.post(new Runnable() {
#Override
public void run() {
myTextView.setText(updateWords);
});
}
}
};
Next just create your thread using the Runnable and start it.
Thread myThread = new Thread(myRunnable);
myThread.start();
You should now see your app looping with no force closes.

You can create a new Thread for a while loop.
This code will create a new thread to wait for a boolean value to change its state.
private volatile boolean isClickable = false;
new Thread() {
#Override
public void run() {
super.run();
while (!isClickable) {
// boolean is still false, thread is still running
}
// do your stuff here after the loop is finished
}
}.start();

How can I make a imageview visible, 5 sec pause, invisible, 5 sec pause and so on

I have an imageView and want it to work like this:
ImageViewer visible
5 second pause
image view invisible
5 second pause
ImageViewer visible
and so on ...
How do I do that? I have tried sleep but it freezes the whole program in 5 seconds. I just want to affect my imageView.

I'm not an Android programmer, but, as a general advice, I'd say you should perform the sleep, better said the waiting, on another thread and execute at the end of the waiting period, on the main thread, a method that toggles the visibility of your imageview.
Getting into more specific detail, I'd say you must use a Handler object because you cannot update most UI objects while in a separate thread. When you send a message to the Handler it will get saved into a queue and get executed by the UI thread as soon as possible:
public class MyActivity extends Activity {
// Handler needed for callbacks to the UI thread
final Handler mHandler = new Handler();
// Create runnable for posting
final Runnable mUpdateUIState = new Runnable() {
public void run() {
updateUIState();
}
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
[ . . . ]
}
protected void startToggle() {
// Fire off a thread to do the waiting
Thread t = new Thread() {
public void run() {
Thread.Sleep(5000);
mHandler.post(mUpdateUIState);
}
};
t.start();
}
private void updateUiState() {
// Back in the UI thread -- toggle imageview's visibility
imageview.setVisibility(1 - imageview.getVisibility());
}
}
or, a snippet of a shorter version,
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
public void run() {
imageview.setVisibility(1 - imageview.getVisibility());
}
}, 5000);
using the postDelayed method, that incorporates the delay within the message posting logic.

Use an AlphaAnimation on the ImageView with a 10 second duration going from alpha 100 to 0 and back to 100 again.
Then use a repeact count of INFINITE.
You can use an interpolator to produce a much pleasant effect while the ImageView appears or disappears.