Android repeatOnLifecycle in fragment inside ViewPager2

Question

If I add the following code snippet to a "normal" fragment it gets started and cancelled as expected when navigating to and from the fragment, but if I add this to fragment inside a view pager 2 it is not cancelled even though the fragmens onPause method is invoked. Is this by design or am I missing something?

lifecycleScope.launch {
    viewLifecycleOwner.repeatOnLifecycle(Lifecycle.State.STARTED) {
        try {
            while (isActive) {
                println("Fragment alive....")
                delay(1000)
            }
        } catch (ex: CancellationException) {
            println("Cancelled fragment...")
            throw ex
        }
    }
}

that depends on your `ViewPager2` adapters implementation, may be proper behavior, when some recycling is implemented — snachmsm, Dec 12 '21 at 13:59

score 1 · Accepted Answer · answered Dec 12 '21 at 15:04

1

I am no sure if I got your question right, but I can already tell that you're relaying on the wrong lifecycle event if you wish that your code gets executed when the Fragment is visible, for that you need to use repeatOnLifecycle(Lifecycle.State.RESUMED). Using this your code will start executing as soon as the Fragment is visible and gets cancelled when it gets paused. Using repeatOnLifecycle(Lifecycle.State.STARTED) your code will start executing when the Fragment is started (ready to get displayed) and gets cancelled when it gets stopped.

answered Dec 12 '21 at 15:04

Muhannad Fakhouri

1,468
11
14

Ah of course.. stupid mistake. Thanks for helping me out! – Kimble Dec 12 '21 at 15:22
happens to the best of us, you're welcome – Muhannad Fakhouri Dec 12 '21 at 15:22
@MuhannadFakhouri can you please check this [issue](https://stackoverflow.com/q/70593277/11560810) – Kotlin Learner Jan 05 '22 at 18:46

Android repeatOnLifecycle in fragment inside ViewPager2

1 Answers1