How to code a counter which loops within an interval in Kotlin Android-CodePudding

I am trying to build a countdown view inside an Android App with Kotlin. The code that I currently have crashes the app while running.

PS: Integer timer should be altered later on the application as well.

var timer:  Int = 50  // Declared globally
private fun timer(){
        timer_text.text = timer.toString()    // Text view in UI

        while (timer > 1){
            Handler().postDelayed({
                timer--
                timer_text.text = timer.toString()   // Update the Text view in UI
            }, 1000)
        }
    }

Logcat

I/sandaru.projec: Thread[6,tid=11100,WaitingInMainSignalCatcherLoop,Thread*=0xb400007b3dcd9f50,peer=0x13280238,"Signal Catcher"]: reacting to signal 3
I/sandaru.projec: 
I/sandaru.projec: Wrote stack traces to tombstoned
D/EGL_emulation: app_time_stats: avg=5.51ms min=1.98ms max=10.47ms count=60

CodePudding user response：

Have you checked out this post? https://developer.android.com/reference/android/os/CountDownTimer

This should suffice for what you have in mind.

CodePudding user response：

Looks like there is an ANR, since you are executing the while loop on main thread, you can try with below code, doing this will suspend instead of blocking

var timer:  Int = 50  // Declared globally
private suspend fun timer(){
    withContext(Dispatchers.Main) {
        timer_text.text = timer.toString()    // Text view in UI

        while (timer > 1){               
            timer--
            timer_text.text = timer.toString()   // Update the Text view in UI
            delay(1000)
        }
    }
}

and you need to execute the code from inside a coroutine, for ex. in the activity/fragment you can execute like this

lifecycleScope.launch {
    timer()        
}