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android – How to call a function after delay in Kotlin?

Posted by: admin March 11, 2020 Leave a comment

Questions:

As the title, is there any way to call a function after delay (1 second for example) in Kotlin?

How to&Answers:

You can use Schedule

inline fun Timer.schedule(
    delay: Long, 
    crossinline action: TimerTask.() -> Unit
): TimerTask (source)

example (thanks @Nguyen Minh Binh – found it here: http://jamie.mccrindle.org/2013/02/exploring-kotlin-standard-library-part-3.html)

import java.util.Timer
import kotlin.concurrent.schedule

Timer("SettingUp", false).schedule(500) { 
   doSomething()
}

Answer:

There is also an option to use Handler -> postDelayed

 Handler().postDelayed({
                    //doSomethingHere()
                }, 1000)

Answer:

Many Ways

1. Using Handler class

Handler().postDelayed({
    TODO("Do something")
    }, 2000)

2. Using Timer class

Timer().schedule(object : TimerTask() {
    override fun run() {
        TODO("Do something")
    }
}, 2000)

Shorter

Timer().schedule(timerTask {
    TODO("Do something")
}, 2000)

Shortest

Timer().schedule(2000) {
    TODO("Do something")
}

3. Using Executors class

Executors.newSingleThreadScheduledExecutor().schedule({
    TODO("Do something")
}, 2, TimeUnit.SECONDS)

Answer:

You have to import the following two libraries:

import java.util.*
import kotlin.concurrent.schedule

and after that use it in this way:

Timer().schedule(10000){
    //do something
}

Answer:

You could launch a coroutine, delay it and then call the function:

 /*GlobalScope.*/launch {
   delay(1000)
   yourFn()
 }

If you are outside of a class or object prepend GlobalScope to let the coroutine run there, otherwise it is recommended to implement the CoroutineScope in the surrounding class, which allows to cancel all coroutines associated to that scope if necessary.

Answer:

val timer = Timer()
timer.schedule(timerTask { nextScreen() }, 3000)

Answer:

A simple example to show a toast after 3 seconds :

fun onBtnClick() {
    val handler = Handler()
    handler.postDelayed({ showToast() }, 3000)
}

fun showToast(){
    Toast.makeText(context, "Its toast!", Toast.LENGTH_SHORT).show()
}

Answer:

If you are looking for generic usage, here is my suggestion:

Create a class named as Run:

class Run {
    companion object {
        fun after(delay: Long, process: () -> Unit) {
            Handler().postDelayed({
                process()
            }, delay)
        }
    }
}

And use like this:

Run.after(1000, {
    // print something useful etc.
})

Answer:

I recommended using SingleThread because you do not have to kill it after using. Also, “stop()” method is deprecated in Kotlin language.

private fun mDoThisJob(){

    Executors.newSingleThreadScheduledExecutor().scheduleAtFixedRate({
        //TODO: You can write your periodical job here..!

    }, 1, 1, TimeUnit.SECONDS)
}

Moreover, you can use it for periodical job. It is very useful. If you would like to do job for each second, you can set because parameters of it:

Executors.newSingleThreadScheduledExecutor().scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit);

TimeUnit values are: NANOSECONDS, MICROSECONDS, MILLISECONDS, SECONDS, MINUTES, HOURS, DAYS.

@canerkaseler