I want to create a simple countdown for my game, when the game starts I want this function to be called every second:
fun minusOneSecond(){
if secondsLeft > 0{
secondsLeft -= 1
seconds_thegame.text = secondsLeft.toString()
}
}
I tried this:
var secondsLeft = 15
timer.scheduleAtFixedRate(
object : TimerTask() {
override fun run() {
minusOneSecond()
}
},0, 1000
) // 1000 Millisecond = 1 second
But the app unfortunately stops, the 2nd time the run function is called
I just started with android development and Kotlin 3 weeks ago and so far I understand the most out of it.
With swift in Xcode I use this line and I thought something similar would work with Kotlin
setTimer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(minusOneSecond), userInfo: nil, repeats: true)
Problem: Timer class uses a background thread with a queue to queue and execute all tasks sequentially. From your code, because you update UI (changing TextView content in minusOneSecond function). That why the app throws the following exception and make your app crash.
android.view.ViewRootImpl$CalledFromWrongThreadException: Only the
original thread that created a view hierarchy can touch its views.
Solution: There are many ways to achieve your task, but I prefer using post() and postDelayed() method from Handler class. Because it's simple and easy to understand.
val mainHandler = Handler(Looper.getMainLooper())
mainHandler.post(object : Runnable {
override fun run() {
minusOneSecond()
mainHandler.postDelayed(this, 1000)
}
})
Update: From author's comment about how to pause/resume the task from Handler. Here is an example.
class MainActivityKt : AppCompatActivity() {
lateinit var mainHandler: Handler
private val updateTextTask = object : Runnable {
override fun run() {
minusOneSecond()
mainHandler.postDelayed(this, 1000)
}
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// Your logic code
...
mainHandler = Handler(Looper.getMainLooper())
}
override fun onPause() {
super.onPause()
mainHandler.removeCallbacks(updateTextTask)
}
override fun onResume() {
super.onResume()
mainHandler.post(updateTextTask)
}
fun minusOneSecond() {
if secondsLeft > 0 {
secondsLeft -= 1
seconds_thegame.text = secondsLeft.toString()
}
}
}
I am using this code to update a clock every minute
fixedRateTimer("timer", false, 0L, 60 * 1000) {
this#FullscreenActivity.runOnUiThread {
tvTime.text = SimpleDateFormat("dd MMM - HH:mm", Locale.US).format(Date())
}
}
so you have to run it with paratemer 1000 instead of 60*1000
val timer = object: CountDownTimer(10000, 1000) {
override fun onTick(millisUntilFinished: Long) {
// do something
}
override fun onFinish() {
// do something
}
}
timer.start()
You can also use CountDownTimer for this purpose. As this takes two parameters (the total time and the interval time)
Plus it also provides an on finish method to perform any task when the total time is finished.
please use
inline fun Timer.schedule(
time: Date,
period: Long,
crossinline action: TimerTask.() -> Unit
): TimerTask
reference: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.concurrent/java.util.-timer/schedule.html
I am calling my function every second like this
val handler = Handler()
handler.postDelayed(object : Runnable {
override fun run() {
//Call your function here
handler.postDelayed(this, 1000)//1 sec delay
}
}, 0)
My solution
viewModelScope.launch(Dispatchers.IO) {
while(isActive) {
when(val response = repository.getApi()) {
is NetworkState.Success -> {
getAllData.postValue(response.data)
}
is NetworkState.Error -> this#MainViewModel.isActive = false
}
delay(API_CALL_DELAY)
}
}
if you use any background task or background service try this code
val timer = Executors.newSingleThreadScheduledExecutor().scheduleAtFixedRate({
Log.d("RUNNING ","Thread")
},0,10,TimeUnit.SECONDS)
if you work with UI thers like update UI layout try this code
val timer = Executors.newSingleThreadScheduledExecutor().scheduleAtFixedRate({
Log.d("RUNNING ","BACKGROUN Thread")
runOnUiThread {
Log.d("RUNNING ","Update UI Thread")
btnUpdate.setText(System.currentTimeMillis().toString())
}
},0,1,TimeUnit.SECONDS)
I'm using recursion with Coroutine its very simple
private fun loop() {
CoroutineScope(IO).launch {
delay(5000)
CoroutineScope(Main).launch {
ManagerToWorker()
loop()
}
}
}
var isActionAchieved = false
var secondsPassed = 0
fun cDTimer(){
if (!isActionAchieved && secondsPassed < 10){ // repeat check if Action NOT Achieved for max of 10 seconds
Handler(Looper.getMainLooper()).postDelayed({
repeatThisFunction()
repeater()
secondsPassed++
}, 1000) //one second till next execution
}
}
fun repeater(){
cDTimer()
}
Related
I am new to Android Development... Sorry for asking something so trivial. I don't know how to google this problem.
So let me explain:
I am doing the Android Development Course from Google and in the exercise you have a TextView that is repeatedly changed by an easy mathematical function 4 times after setContentViewis called. Between the changes Thread.sleep(1000) is called to delay the changes.
Expected behavior:
The Main Activity starts and you can see the TextView changing 4 times.
What actually happens:
The App start is delayed for as long as the calculations are set and then afterwards it will display the Main Activity with only the very last calculated result. In this case I would wait 4 seconds (with Thread.sleep(1000) being called 4 times) until the App is completely up and then you only see the result 60 because of 60 / 1.
This is the code:
private const val TAG = "MainActivity"
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
division()
}
private fun division() {
val numerator = 60
var denominator = 4
repeat(4) {
Thread.sleep(1000)
Log.v(TAG, "${numerator / denominator}")
val view: TextView = findViewById(R.id.division_textview)
view.setText("${numerator / denominator}")
denominator--
}
}
Thanks in advance. I hope someone knows why Google is suggesting this code, but it does not work on my machine.
You need to make a delay by Timer instead of Thread.sleep()
For training you can try something like this.
private val timerHandler = Handler(Looper.getMainLooper())
private val timerRunnable = Runnable {
denominator--
if(demominator != 0) {
//UI changes here
decrementTimer()
}
}
private fun decrementTimer() {
timerHandler.postDelayed(timerRunnable, DELAY_TIME)
}
If you need to start first run immediately use timerRunnable.run() in other case call decrementTimer().
Also would be helpful to control handler with removeCallbacks function when activity goes to background
You can wait in another thread so you don't block the main thread,
try this code it should work correctly, the code inside the lifecycleScope.launch will be moved to another thread so it will not block the UI:
private const val TAG = "MainActivity"
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
division()
}
private fun division() {
val numerator = 60
var denominator = 4
lifecycleScope.launch {
repeat(4) {
delay(1000)
Log.v(TAG, "${numerator / denominator}")
val view: TextView = findViewById(R.id.division_textview)
view.setText("${numerator / denominator}")
denominator--
}
}
}
Note: You need to be sure that you add the lifecycle dependency in you app gradle
dependencies {
...
implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.4.1'
...
}
Thanks for your answers everyone. Each of them helped me searching for the right topics. I liked the Handler Class the most and after some further searching, I came up with this solution:
private fun division() {
val numerator = 60
var denominator = 4
val handler = Handler(Looper.getMainLooper())
val divRunnable = object: Runnable {
override fun run() {
if (denominator != 0) {
Log.v(TAG, "${numerator / denominator}")
val view: TextView = findViewById(R.id.division_textview)
view.text = "${numerator / denominator}"
denominator--
handler.postDelayed(this, 1000)
}
}
}
handler.post(divRunnable)
}
This is working exactly as I wanted it to work.
Im trying to stop Counter when time is over. But in my situation when time is over, timer restart and counting again. I don't know why my onFinish method doesn't work good. Thanks for all support.
countDownTimer = object : CountDownTimer(timeLeftInMillis, 1000) {
override fun onTick(millisUntilFinished: Long) {
timeLeftInMillis = millisUntilFinished
updateCountDownText()
}
override fun onFinish() {
isRunning = false
isStartingAlarm = true
startPauseButton.text = "Start"
startPauseButton.visibility = View.INVISIBLE
resetButton.visibility = View.VISIBLE
alarmSound.start()
}
}.start()
I have created StopWatch function for Android app in Kotlin using Timer class. I am using activity?.runOnUiThread to display the time in the App Bar (not in View). Is there any simple way to stop timer and set it back to 0. Is the multithreading necessary?
Here is my function:
private fun stopwatch(isCanceled: Boolean) {
val timer = Timer()
val tt: TimerTask = object : TimerTask() {
override fun run() {
num += 1000L
val runnable = Runnable { setModeTitle(getString(R.string.chipper_title) + TimerUtil.timerDisplay(num)) }
activity?.runOnUiThread(runnable)
}
}
timer.schedule(tt, 0L, 1000)
if (isCanceled) {
//what to implement here, if possible?
}
}
You need to store a resulting TimerTask object and later call cancel() on it. Something like:
private var tt: TimerTask? = null
private fun stopwatch() {
val timer = Timer()
tt = object : TimerTask() {
override fun run() {
num += 1000L
val runnable = Runnable { setModeTitle(getString(R.string.chipper_title) + TimerUtil.timerDisplay(num)) }
activity?.runOnUiThread(runnable)
}
}
timer.schedule(tt, 0L, 1000)
}
private fun cancelStopwatch() {
tt?.cancel()
}
Just make sure not to call stopwatch() twice, without first cancelling an already running stopwatch.
I have a video of 10 seconds. I want to loop a segment from 2 seconds to 6 seconds. Starting the player at the right time is easy:
player?.seekTo(2000)
I don't think there is a functionality available in the ExoPlayer2 library to define an end position. So I tried to add a delay co-routine. With the method seekToPositionAndStartCounter. This works in a separate project. But used in the actual project, onPlayerStateChanged gets triggered a lot of times all of a sudden.
var elapsedTime = 0L // just for testing
private fun showVideoWhenDoneLoading() {
videoView?.player?.addListener(object : Player.EventListener {
override fun onPlayerStateChanged(playWhenReady: Boolean, playbackState: Int) {
super.onPlayerStateChanged(playWhenReady, playbackState)
if (playbackState == Player.STATE_READY) {
if (playWhenReady) {
seekToPositionAndStartCounter()
} else {
cancelCounter()
}
}
}
})
}
private fun seekToPositionAndStartCounter() {
elapsedTime = System.currentTimeMillis()
cancelCounter()
job = GlobalScope.launch(Dispatchers.IO) {
Timber.d("starting Thread name = ${Thread.currentThread().name}")
player?.seekTo(startPosition)
if (duration != 0L) {
runBlocking {
delay(duration)
}
GlobalScope.launch(Dispatchers.Main) {
Timber.d("duration = $duration elapsedTime = ${System.currentTimeMillis()-elapsedTime} Thread name = ${Thread.currentThread().name}")
seekToPositionAndStartCounter()
}
}
}
}
private fun cancelCounter() {
job?.cancel()
job = null
}
If you don't try this then think about this.
getCurrentPosition of player and if player reach end position which you want then run player.seekto(2) it loops the video in specific segment of video.
in the timer I use how to add a time when a button is pressed? for example, I want millisUntilFinished to increase by 5 seconds when I press a button. I tried with the global variable but it didn't.
object :CountDownTimer(10000,1000){
override fun onFinish() {
timeText.text = "Left : 0"
handler.removeCallbacks(runnable)
for (image in imageArray){
image.visibility = View.INVISIBLE
}
for (add in timeAdd){
add.visibility = View.INVISIBLE
}
button.visibility = View.VISIBLE
}
override fun onTick(millisUntilFinished: Long) {
timeText.text = "Left : "+millisUntilFinished/1000
}
}.start()
Here is a count down timer we use
fun message(msg:String){
object : CountDownTimer(4000, 1000) {
override fun onTick(millisUntilFinished: Long) {
tvMsg.visibility = View.VISIBLE
tvMsg.text = msg
}
override fun onFinish() {
tvMsg.visibility = View.INVISIBLE
tvMsg.text = ""
}
}.start()
}
And our use of a plain timer
if (result) {
etItemData.setText("")
message("Record Removed")
Timer().schedule(1000){
thisACTIVITY()
}
Kotlin complains about this not sure why
addition to Vector's answer I made an button that display countdown timer every 1 second. I put Vector's answer into a function then call it when my button is pressed. Hope this help someone. With this example it counts down from 4 seconds.
private fun countdown(){
object : CountDownTimer(4000, 1000) {
override fun onTick(millisUntilFinished: Long) {
otp_resend.text = (millisUntilFinished / 1000).toString()
}
override fun onFinish() {
// do something after countdown is done ie. enable button, change color
etc.
otp_resend.text = "done!"
}
}.start()
}
You can't change the remaining time on an already-created CountDownTimer.
Looking at the source, both millisInFuture and countDownInterval are assigned to final variables; you can't change them.
Now, the mStopTimeInFuture variable, the one the timer actually uses to stop, isn't final, and can be changed. But it's a private variable, meaning you'd need to use reflection, and it might not work properly.
If you want a mutable CountDownTimer, you'll need to roll your own (easiest way would probably be to copy the CountDownTimer source and make the mStopTimeInFuture variable public and add milliseconds to it when needed).
As #TheWanderer answered you can not update the millisUntilFinished as there is no such method available in CountDownTimer class.
To update the Timer you need to stop the current timer and start the new timer with updated millisInFuture value. Here is the sample code which will help you to achieve what you want.
var timer: Timer?=null
//Call this method to start timer on activity start
private fun startTimer(){
timer = Timer(10000);
timer?.start()
}
//Call this method to update the timer
private fun updateTimer(){
if(timer!=null) {
val miliis = timer?.millisUntilFinished + TimeUnit.SECONDS.toMillis(5)
//Here you need to maintain single instance for previous
timer?.cancel()
timer = Timer(miliis);
timer?.start()
}else{
startTimer()
}
}
inner class Timer(miliis:Long) : CountDownTimer(miliis,1000){
var millisUntilFinished:Long = 0
override fun onFinish() {
timeText.text = "Left : 0"
handler.removeCallbacks(runnable)
for (image in imageArray){
image.visibility = View.INVISIBLE
}
for (add in timeAdd){
add.visibility = View.INVISIBLE
}
button.visibility = View.VISIBLE
}
override fun onTick(millisUntilFinished: Long) {
this.millisUntilFinished = millisUntilFinished
timeText.text = "Left : "+millisUntilFinished/1000
}
}