Develop Reference

Android Why does this line of code execute after the for loop?

btnSwitch2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
btnSwitch2.setImageResource(R.drawable.on);
myVib.vibrate(50);
strobeFlash();
}
});
}
private void strobeFlash(){
for(int i=0; i<10;++i){
turnOnFlash2();
turnOffFlash2();
}
}
The code above executes when a button is pressed, I would like to change the picture of the image button. However, when the button is pressed, the for loop executes first then the line above it
btnSwitch2.setImageResource(R.drawable.on);
executes. Is there something I'm doing that's causing the loop to execute completely first?

Actually for loop execution is faster the then changing the image resource. You can add a postDelay() between the UI update and the for loop execution.
It will solve the issue.
btnSwitch2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
btnSwitch2.setImageResource(R.drawable.on);
myVib.vibrate(50);
handler=new Handler();
Runnable r=new Runnable() {
public void run() {
strobeFlash();
}
};
handler.postDelayed(r, 3000);
}
});
}
private void strobeFlash(){
for(int i=0; i<10;++i){
turnOnFlash2();
turnOffFlash2();
}
}

Android Animation Lags (what's the difference between two methods)

I want to animate a movement of images.
I have two different implementations, the first involves two methods and runs smoothly, the other only needs one method and lags. I'd rather use the second one but can't figure out what causes the lags.
I don't think it's the code that calculates the new positions since it's very simple and in both methods almost the same (I removed it for better readability)
Here is the first:
public void animateCircleMovement(final long duration) {
// ...
post(new Runnable() {
#Override
public void run() {
animateStep();
}
});
}
public void animateStep() {
// ...
invalidate();
if(curTime<endTime) {
post(new Runnable() {
#Override
public void run() {
animateStep();
}
});
}
}
Here is the second
// ...
new Thread(new Runnable() {
#Override
public void run() {
while(currTime<endTime){
// ...
postInvalidate();
}
}).start();
Why does the second implementation cause lags?
Edited the postInvalidate() method

The animation runs smoothly if Thread.Sleep(10) is put into the while-loop.

How can I wait for a period of time after a button is clicked?

So I have an activity which runs a simple snakes and ladders game, and I want to allow the player to click a button and move, which would subsequently be followed by the computer moving. My problem is, that once the player moves, the computer immediately makes its move.
Instead I want the activity to wait before the computer makes its move. I've looked around a lot and found that waiting involves using a thread, but I have failed to implement it without my app crashing
My attempt at declaring a thread:
final Runnable runnable = new Runnable() {
#Override
public void run()
{
while (true)
{
try
{
Thread.sleep(5000);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
}
}
};
Thread thread= new Thread(runnable);
My onClick() method for the button:
Button rollButton = (Button) (findViewById(R.id.rollButton));
rollButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//executes only if current player is a human
if(GAME_BOARD.getCurrentPlayer().isHuman()) {
GAME_BOARD.rollDie(); // rolls the die
showDie(GAME_BOARD); // displays die on screen
GAME_BOARD.move(); // moves the player and sets next player as current player
playerTurn.setText(GAME_BOARD.getCurrentPlayer().getName() +"'s turn");// sets TextView to display who's player's turn it is
thread.start();
if(!GAME_BOARD.getCurrentPlayer().isHuman()) {
GAME_BOARD.rollDie();
showDie(GAME_BOARD);
GAME_BOARD.move();
playerTurn.setText(GAME_BOARD.getCurrentPlayer().getName() +"'s turn");
}
}
}
});
So again, my question is, how do I make it so that before the second if statement executes, the activity waits, say 4 seconds?

you can use an Handler.postDeleayed. You have to provide a Runnable to execut and the delay period in milliseconds. The Runnable will be executed on the UI Thread

You can use Handle to post your task defined in runnable after some delay
use this
Inside Activity define
Handler hand = new Handler();
and define your task in runnable like this
Runnable run = new Runnable() {
#Override
public void run() {
**your Task here.......**
}
};
In on click event
btnStartShow.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
hand.postDelayed(run,3000); // For delay three seconds
}
});
also remove all pending messages by calling following sentence at appropriate place
hand.removeCallbacksAndMessages(null);

Use a CountDownTimer:
CountDownTimer timer = new CountDownTimer(4000, 1000) {
#Override
public void onFinish() {
*function containing the second statement*
}
#Override
public void onTick(long millisLeft) {
// not ticking
}
};
and in the onClick method in the click listener use:
timer.start();

Try the following,
rollButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Runnable runnable = new Runnable() {
#Override
public void run() {
// whatever you would like to implement when or after clicking rollButton
}
};
rollButton.postDelayed(runnable, 5000); //Delay for 5 seconds to show the result
}

Android - How do I set View.GONE outside the UI thread?

I want to make a view disappear (to be gone) when the user pushes a button.
I can make it inside the onCreate() method (main UI thread) by doing:
findViewById(R.id.llLoadingGallery).setVisibility(View.GONE);
However, I want to be able to do the same thing inside another thread (out of the main UI thread). I tried to put the above live in my thread and it didn't work.
Thank you in advance!
## EDIT ####
To make myself more clear, I want to do something like this:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.teste_aba_3);
botao_tab_musica.setOnClickListener( new View.OnClickListener() {
#Override
public void onClick(View v) {
...
findViewById(R.id.llLoadingGallery).setVisibility(View.GONE);
}
});
}
However, that DOESN'T work! How can I fix this?

theres a neat method called runOnUiThread
runOnUiThread(new Runnable() {
#Override
public void run() {
findViewById(R.id.llLoadingGallery).setVisibility(View.GONE);
}
});
edit: with your code
botao_tab_musica.setOnClickListener( new View.OnClickListener() {
#Override
public void onClick(View v) {
runOnUiThread(new Runnable() {
#Override
public void run() {
findViewById(R.id.llLoadingGallery).setVisibility(View.GONE);
}
});
}
});

I'd suggest either using View.post(Runnable), View.postDelayed(Runnable, long), a Handler, or an AsyncTask to do this for you.
There are some good examples on how to post to the UI thread in these scenarios:
http://developer.android.com/resources/articles/painless-threading.html

I think one possibility is to pass a reference to your activity to that other thread so that your thread can access the findViewById method.

try this
findViewById(R.id.llLoadingGallery).post(new Runnable()
{
#Override
public void run()
{
findViewById(R.id.llLoadingGallery).setVisibility(View.GONE);
}
});
or create AsyncTask

How to create a spinner while url is looked up?

I would like the user to press a button.
When the onClickListener for the button is called, I would like to display a spinner until the webpage is fetched.
I don't want to use a AsyncTask because it can only be run once and more than likely the user will click the button more than once after the first url results are retreived.
So how would I go about doing this with this onClickListener?
findIT.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
item = game.getText().toString();
getUserPreference();
itemLookup.loadUrl(url);
}
});

You can still use AsyncTask<>, you just have to create a new one each time.
public void onClick(View v) {
new DoWhateverTask().execute();
}
Otherwise you can do it yourself using Handlers. Assuming you already have Handlers defined for the UI and a worker thread:
public void onClick(View v) {
showProgress();
workerThreadHandler.Post(new Runnable() {
public void run() {
doNetworkStuff(); // Which will post progress to the UI thread if needed.
mainThreadHandler.Post(new Runnable() {
public void run() {
hideProgress();
}
});
}
});
}
Personally, I think AsyncTask is a nicer solution.