How to implement a time scheduler in Kotlin

Question

So I want my app to perform an operation at certain intervals of time. After doing a little research I found the some answers on stackoverflow and it led me to this link to something called fixedRateTimer: Heres the first example in that page

    val fixedRateTimer = fixedRateTimer(name = "hello-timer",
    initialDelay = 100, period = 100) {
    println("hello world!")}

    try {
   Thread.sleep(1000)
   } 

   finally {
   fixedRateTimer.cancel();
   }

When I added that snippet of code I get an error.

"Expression 'fixedRateTimer' cannot be invoked as a function. The function 'invoke()' is not found Variable 'fixedRateTimer' must be initialized"

I did more research and imported kotlin.concurrent.schedule* and kotlin.concurrent.fixedRateTimer and added a block of code on top of the first to initilize it.

So it fixed the first block code but the one I just added gave me more errors. It stated the function needed to be abstract. So i made it abstract but then an error appeared at the bottom of crossinline stating that the function needs to be inline and not abstract.

So im going crazy because all the code blocks I took are from the documentations so im not sure why im getting these errors. As a beginner Im trying to follow the documentation but im always at a lost at every turn. There were some other answers on that Stackoverflow page I linked like Handlers and schedules but I was still getting similiar type of errors.

So how do I use schedule or fixedRateTimer ? I would appreciate a step-by-step example so I could a get fully understanding of what im typing

Thanks!

try workmanager. https://developer.android.com/topic/libraries/architecture/workmanager/basics — sadat, Oct 23 '20 at 00:15

Rishabh Ritweek · Accepted Answer · 2020-10-25T18:38:11.777

3

Option 1 : use this link :-

https://developer.android.com/topic/libraries/architecture/workmanager/basics

Now, since you want to do a periodic task, you have to use,

Periodic Work request instead of OneTimeWorkRequest and you can set the interval here.

 PeriodicWorkRequest saveRequest =
   new PeriodicWorkRequest.Builder(SaveImageToFileWorker.class, 1, TimeUnit.HOURS)
       // Constraints
       .build();

Follow this example :-

https://developer.android.com/topic/libraries/architecture/workmanager/how-to/define-work

Note :-Use of WorkManager API cannly be done if minimum API that you are targetting your app is Android 5.0

option 2 :

   new CountDownTimer(30000, 1000) {

 public void onTick(long millisUntilFinished) {
     mTextField.setText("seconds remaining: " + millisUntilFinished / 1000);
 }

 public void onFinish() {
     mTextField.setText("done!");
 }

}.start();

edited Oct 25 '20 at 18:38

answered Oct 23 '20 at 01:16

Rishabh Ritweek

550
3
10

After reading about workManager I feel like its too big for what I want to do. My app simply runs a simple calculation every hour and puts it out in the UI. However, I will still attempt implemeneting that – Crimson Space Oct 23 '20 at 02:21
It's part of Android JetPack..added advantage is that it has less chances of being deprecated in the future. You can even job Scheduler if your app is not gonna run on Android 30. – Rishabh Ritweek Oct 23 '20 at 03:08
ok after struggling to get it to work its finally working thanks for your help! marked – Crimson Space Oct 24 '20 at 06:26
adding option 2 as well . – Rishabh Ritweek Oct 25 '20 at 18:37

How to implement a time scheduler in Kotlin

1 Answers1