Develop Reference

Problem syncing custom timer to system clock

I have a custom timer that I'm keeping synced to the system clock. It's working fine for one minute intervals, but I also need it to sync to 36 second intervals (for updating fields when the user wants times displayed in decimal hours). Inside the Runnable I recalculate the adjustment (accurate enough for my needs) for the next minute, but can't find a way to conveniently deal with the different offsets needed for 36 seconds.
EDIT
private static class DecimalTimer extends TimerClass {
final int[] seconds = new int[101];
private boolean keepRunning = true;
private Runnable mRunnable;
#Override
void kill() {
keepRunning = false;
}
#Override
Runnable getRunnable() {
return mRunnable;
}
DecimalTimer() {
final int[] counter = new int[1];
for (int i = 0, j = 0; i < 3600; i += 36, j++) {
seconds[j] = i;
}
mRunnable = new Runnable() {
#Override
public void run() {
if (!keepRunning)
return;
final Calendar c = Calendar.getInstance();
int hourSeconds = c.get(Calendar.MINUTE) * 60 + c.get(Calendar.SECOND);
for (counter[0] = 0; counter[0] < 100; counter[0]++) {
if (seconds[counter[0]] > hourSeconds) {
c.add(Calendar.SECOND, seconds[counter[0]]);
break;
}
}
long adjustedDelay = (c.getTimeInMillis() - System.currentTimeMillis()) % 36000;
for (IntervalTimer listener : sListeners) {
listener.updateTime();
}
sHandler.postDelayed(this, adjustedDelay);
}
};
}
}
This edit fires every 36 seconds, but I need to get it to sync to 36 seconds on the clock (ie: 12:00:00, then 12:00:36 .. 12:01:12 .. 12:01:48)

Overthinking things as usual, this is what I came up with. It's accurate enough for what I need, but if anyone has an improvement for accuracy (It's a little off when it executes with 900ms or more) it'd be appreciated.
DecimalTimer() {
mRunnable = new Runnable() {
#Override
public void run() {
if (!keepRunning)
return;
final Calendar c = Calendar.getInstance();
c.set(Calendar.MINUTE, 0);
c.set(Calendar.SECOND, 0);
do {
c.add(Calendar.SECOND, 36);
} while (c.getTimeInMillis() < System.currentTimeMillis());
long adjustedDelay = (c.getTimeInMillis() - System.currentTimeMillis()) % 36000;
for (IntervalTimer listener : sListeners) {
listener.updateTime();
}
sHandler.postDelayed(this, adjustedDelay);
}
};
}

How to set a delay in Android

I'm making a Simon game, while doing it, I created an method that called "Computer" that is activated when the game is starting and after that, every time after the player successes to repeat the sequence.
Here is the code:
private void Computer(){
rounds.setText("Round " + index);
new CountDownTimer(500, 500) {
public void onTick(long millisUntilFinished) {
}
public void onFinish()
{
ResetArray(Player);
//Pushing buttons
Red.setClickable(false);
Blue.setClickable(false);
Green.setClickable(false);
Yellow.setClickable(false);
for (int i = 0; i < index; i++)
{
final Handler handler = new Handler();
final int temp=Game[i];
if (temp == 0)
{
Red.setImageResource(R.drawable.red1);
handler.postDelayed(new Runnable() {
#Override
public void run()
{
StartSound(red);
Red.setImageResource(R.drawable.red);
}
}, 100);
}
if (temp == 1)
{
Green.setImageResource(R.drawable.green1);
handler.postDelayed(new Runnable() {
#Override
public void run() {
StartSound(green);
Green.setImageResource(R.drawable.green);
}
}, 100);
}
if (temp == 2)
{
Blue.setImageResource(R.drawable.blue1);
handler.postDelayed(new Runnable() {
#Override
public void run() {
StartSound(blue);
Blue.setImageResource(R.drawable.blue);
}
}, 100);
}
if (temp == 3)
{
Yellow.setImageResource(R.drawable.yellow1);
handler.postDelayed(new Runnable() {
#Override
public void run() {
StartSound(yellow);
Yellow.setImageResource(R.drawable.yellow);
}
}, 100);
}
}
Red.setClickable(true);
Blue.setClickable(true);
Green.setClickable(true);
Yellow.setClickable(true);
}
}.start();
}
So basically, what iv'e done here is a short delay, of 500 milliseconds, and then it is starting with the self "pushing". This is for create some space between the beginning of the game/starting a new round.
Index- round number.
Game- an array that iv'e created, where there is 50 random numbers which presents the sequence, every round i'm adding one for the index.
Red, Green, Blue, Yellow - References for ImageButtons.
The handler delay is to give some time between the button pressing (which presented by switching the image resource to a same color but brighter, that gives the effect of pressing a button) and un-press it, without it, the changing will be so fast so the player will not be able to see any graphical change.
Basically I need a way to stop the program for a while between each pushing. I need a delayer that will delay the loop every time at it's beginning. The countdowntimer and the Handler are not suitable because the program keeps "running" after the declaring and setting those, the only effect is that the buttons are pushed together but in a delay, which is not what I need.
The result now is that the buttons are seems pushed together and I need to separate their pushing in some way.
Iv'e tried everything, and I could not find nothing.
Thanks,
Ziv.

Using a Handler and postDelayed(...) IS exactly what you need but you're a approaching it wrong.
Basically what you are doing is running through your for loop almost instantly and at each loop you're calling postDelayed(...) with a delay of 100ms.
I'll explain further - suppose index is 4 and it only takes 1ms to go through each run of the for loop. When the 4 runs of the loop are complete you'll have 4 postDelayed events with times of 100ms, 99ms, 98ms & 96ms - - to all intents and purposes, when they trigger they all appear to trigger at once.
One easy way around this with your code is to increase each delay based on the loop count...
int delayTime;
for (int i = 0; i < index; i++)
{
delaytime = (i + 1) * 100;
final Handler handler = new Handler();
final int temp=Game[i];
if (temp == 0)
{
Red.setImageResource(R.drawable.red1);
handler.postDelayed(new Runnable() {
#Override
public void run()
{
StartSound(red);
Red.setImageResource(R.drawable.red);
}
}, delayTime); // NOTE USING delayTime AS THE DELAY
}
//
// REPEAT THE ABOVE CODE FOR BLUE, GREEN & YELLOW HANDLER DELAYS
}
In other words when i=0, delayTime will be 100ms, when i=1, delayTime is 200ms etc etc

probably you want to sleep the thread for 500 milliseconds, then you can do this to slept your thread.
try {
Thread.sleep(500);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

How do you change label text in java after a timer ticks a second passed?

I have a timer with a delay of 5 seconds. I am trying to change the label named lblTimer after a second passes to act as a countdown. I am having issues with it as currently it only works at 5 seconds. Do you have any suggestionsuggestions?
protected void Addition() {
//addition function
final int delay = 5000; //milliseconds
ActionListener taskPerformer = new ActionListener() {
#SuppressWarnings("unused")
public void actionPerformed(ActionEvent evt) {
//...Perform a task...
frame.getContentPane().setBackground(Color.red);
}
};
new Timer(delay, taskPerformer).start();
Random RandomNumber = new Random();
int number1 = RandomNumber.nextInt(12);
int number2 = RandomNumber.nextInt(12);
int number3 = RandomNumber.nextInt(12);
lblAnswer.setText("");
lblFirstNumber.setText(""+ number1);
lblfunction1.setText("+");
lblsecondNumber.setText(""+number2);
lblfunction2.setText("+");
lblthirdnumber.setText(""+number3);
lblequals.setText("=");
answer = number1+number2+number3;
if(delay <= 1000){
lblTimer.setText("1");
}
else if(delay == 2000){
lblTimer.setText("2");
}
else if(delay == 3000){
lblTimer.setText("3");
}
else if(delay == 4000){
lblTimer.setText("4");
}
else if (delay == 5000){
lblTimer.setText("5");
}
}

The answer to your question, that I assume is "why does this not work?", is that at no point do you recheck the elapsed time. The variable delay is always set at 5000, and never updated, also.
The stupid-ass solution:
lblTimer.setText("5");
Thread.sleep(1000)
lblTimer.setText("4");
Thread.sleep(1000)
lblTimer.setText("3");
Thread.sleep(1000)
lblTimer.setText("2");
Thread.sleep(1000)
lblTimer.setText("1");
Thread.sleep(1000)
lblTimer.setText("0");
Don't really do this, unless you need to satisfy your sick fetishes.
The four-liner
The same as above. Don't do this.
for (int i = secondsToWait; i >= 0; i--) {
lblTimer.setText(i + "");
Thread.sleep(1000);
}
The acceptable solution:
Use a Timer to schedule a task to be executed after a given period of time. You can use timers to also fire the same task multiple times at a given interval.
Timer timer = new Timer();
int secondsToWait = 5;
TimerTask task = new TimerTask() {
#Override
public void run() {
secondsToWait--;
lblTimer.setText(secondsToWait + "");
if (secondsToWait == 0) {
timer.cancel();
timer.purge();
}
}
};
lblTimer.setText(secondsToWait + "");
timer.scheduleAtFixedRate(task, 1000, 1000);
The best solution:
Instead of a timer, use a ScheduledExecutorService. This is better because of the way ScheduledExecutorService works with threads as opposed to Timer. Google it.
ScheduledExecutorService exec = Executors.newScheduledThreadPool(1);
int secondsToWait = 5;
Runnable task = new Runnable() {
#Override
public void run() {
secondsToWait--;
lblTimer.setText(secondsToWait + "");
if (secondsToWait == 0) {
exec.shutdown();
}
}
};
lblTimer.setText(secondsToWait + "");
exec.scheduleAtFixedRate(task, 1, 1, TimeUnit.SECONDS);
EDIT: As Stefan pointed out, for swing GUI applications a swing Timer would be the best pick.

It should look something like this:
1) create Timer
2) create TimerTask and implement run method (updating your count variable and check if counter is zero. if it is zero, stop the timer)
3) schedule the task to run every second
int count = [INITVALUE];
...
public void startMethod() {
final Timer timer = new Timer();
timer.shedule(new TimerTask() {
#Override
public void run() {
count--;
lblTimer.setText(count+"");
if (count == 0) {
timer.cancel();
timer.purge();
}
}
},1000);
}

Thumbs Up #Olavi Mustanoja your answer revealed an option I have never tried before now.
As he lastly suggested on his edit the javax.swing.Timer comes in very handy if you're work with GUI.
import javax.swing.Timer;
private int secondsToWait = 5000; //Time in milliseconds
private Timer timer;
....
//The following section should be inside a method member
timer = new Timer(secondsToWait, e -> {
if(secondsToWait == 0)
timer.stop();//Stop if secondsToWait is already zero
lblTimer.setText((secondsToWait/1000) + ""); //Update the label with the current sec
timer.setDelay(secondsToWait);
secondsToWait -= 1000; //Reduce time by 1sec each time
});
timer.start();
...

Java - Subtract 32 from a number in a specific amount of time

I was wondering... Is there a way that I could subtract 32 from a number in a specific amount of time? Such as 500 mils?
If you could help out, it would be great!
Thanks!
public void update() {
x += dx;
if(this.y % 32 == 0) {
this.tileY = this.y / 32;
}
if(this.x % 32 == 0) {
this.tileX = this.x / 32;
}
System.out.println(tileX);
}
public void moveLeft () {
// subtract 32 dx in 500 ms
}

Well, here is a lovely code I've developed for you. I've added the keyword static to be able to call it from main without creating any objects, but it does not use anything from a static context.
As my comments through the code try to explain, this isn't the perfect solution, it's just a start, you may face issues such as multi-threading errors (if you decide to use a separate Thread to update the position) or slight timing issues if the body of the method takes a while to execute.
If you feel the nanosecond precision is a bit too much for your purposes, remember there is also Thread.sleep(int milis).
Here is the code (try changing the values calling moveLeft(int, int) to see the results):
public class Slider {
public static void main(String[] args) {
Thread thread = new Thread() {
#Override
public void run() {
/*
* If you are going to use something like this, beware you are multi-threading
* Make sure what you do is thread-safe
*/
moveLeft(32, 500);
}
};
thread.start();
}
public static void moveLeft(int distance, int milis) {
//time_px is how many nanoseconds the Thread can sleep until it has to move 1 dx
double time_px = (100000*milis)/distance;
if (time_px >= 1) {
//Get the milis and nanos, rounding for Thread.sleep
long time_round = (long) Math.floor(time_px);
long milis_sleep = time_round/100000;
System.out.print("Waiting " + milis_sleep + "ms ");
int nano_sleep = (int) (time_round%100000);
System.out.println(nano_sleep + "ns per dx");
for (int i=0; i<distance; i++) {
try {
Thread.sleep(milis_sleep, nano_sleep);
/*
* Your code here
* A long code here might not get you the desired result since the sleeping does
* not account for the time spent processing the code. But this is a good start
*/
System.out.println("moving 1 dx");
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
}
else {
System.out.println("Cannot go that fast");
//If you are moving that fast (more than 1 dx per nanosecond) then you need to change this up a little.
}
}
}

Reasons for my drawing thread to suddenly stop?

#Override
public void run() {
super.run();
final float timePerFrame = 1000 / Options.MAX_FPS;
float timeDiff;
while(!isInterrupted() && isRunning) {
timeDiff = System.currentTimeMillis();
mController.refresh();
timeDiff = timePerFrame - (timeDiff - System.currentTimeMillis());
try {
Thread.sleep(Math.max(Math.round(timeDiff), 0));
} catch(InterruptedException e) {
// do nothing
e.printStackTrace();
}
}
Log.e("GameThread", "Thread dead.");
}
This is what my thread is basically doing.
Options.MAX_FPS = 30;
To limit the frames per second, to have some sort of sleeping time between each refresh. The refresh method looks like this:
public synchronized void refresh() {
int mRotation = Math.round((360 + ((-1)*mAccelerometer[0] * 4.5f)) % 360);
mObject.setRotation(mRotation);
// get canvas from surfaceview
if(mSurfaceHolder != null) {
// do all calculations.
if(Looper.myLooper() == Looper.getMainLooper()) {
log("on main thread!");
} else {
log("Not on main thread");
}
Canvas mCanvas = mSurfaceHolder.lockCanvas();
if (mCanvas != null) {
// shift x offset
mScreenWidth = mCanvas.getWidth();
mScreenHeight = mCanvas.getHeight();
// draw black background, clear everything.
mCanvas.drawRect(new Rect(0,0,mScreenWidth, mScreenHeight), mBlackPaint);
// shift & draw all viewobjects if still visible
for(ViewObject view: mViewObjectList.toArray(new ViewObject[mViewObjectList.size()])) {
view.shiftX(-1 * Options.Gameplay.Environment.MOVING_SPEED);
if(view.getX() + view.getWidth() < 0) {
mViewObjectList.remove(view);
}
if(view.getCurrentBitmap() != null)
mCanvas.drawBitmap(view.getCurrentBitmap(), new Rect(0,0,view.getCurrentBitmap().getWidth(), view.getCurrentBitmap().getHeight()), new Rect(view.getX(), view.getY(), view.getX()+ view.getWidth(), view.getY()+view.getHeight()), new Paint());
view.nextFrame();
}
// draw object
final Bitmap sBitmap = mObject.getCurrentBitmap();
mObject.nextFrame();
if(sBitmap != null) {
mCanvas.drawBitmap(sBitmap, new Rect(0, 0, sBitmap.getWidth(), sBitmap.getHeight()), new Rect(mObject.getX(), mObject.getY(), sBitmap.getWidth(), sBitmap.getHeight()), new Paint());
} else log("bitmap = null!");
}
mSurfaceHolder.unlockCanvasAndPost(mCanvas);
}
}
The thread keeps running for some time, background elements are being drawn (even though my rotation does not work quite yet, but that's another story..), the background "seems" to move (like a side-scroller), but at some random point in time, without any ADB LogCat messages (not limited to the App but the whole LogCat output) - the thread simply stops. No more drawing. Nothing. I am not calling interrupt or setting isRunning to false, as the "Thread dead." message is not written into LogCat as well..
I do not know what's happening.
Thanks for your help.

You have:
timeDiff = System.currentTimeMillis();
// refresh, which takes some time I guess
timeDiff = timePerFrame - (timeDiff - System.currentTimeMillis());
so System.currentTimeMillis() will be later and therefore bigger than timeDiff. The term in brackets will be negative - so you will be adding onto the timePerFrame and timeDiff will grow not reduce.