How can I change background with random time?

Question

I'm new on Stack Overflow and I want to learn answer this question please don't give me negative reputation.

How can I change background color with random time and everytime on Android Studio ? I'm using Kotlin language.

var counter:Int =0

        if (Random.nextBoolean())
            background.setBackgroundColor(Color.GREEN)
        else
            background.setBackgroundColor(Color.RED)

        btn_touch.setOnClickListener {

            counter += 1
            textCounter.text = counter.toString()

_When_ do you want the background to change? Every second? Every time the user visits the screen? Every time someone clicks a button? — Ben P., Feb 04 '20 at 21:20
I want to change background random time for example 5 second after green and then maybe 1 second after will change red. Can i explain ? — life4, Feb 04 '20 at 21:39

score 1 · Answer 1 · answered Feb 04 '20 at 22:50

1

Try the following code snippet

val maxDelay = 10000L
val handler = Handler()
var isRed = true;
val updateRunnable = object : Runnable {
    override fun run() {
        background.setBackgroundColor(if(isRed) Color.RED else Color.GREEN)
        isRed = !isRed
        handler.postDelayed(this, Random.nextLong(maxDelay))
    }
}
handler.post(updateRunnable)

Set maxDelay value as you need and don't forget to call handler.removeCallbacks(updateRunnable) when you don't need it anymore.

answered Feb 04 '20 at 22:50

Mir Milad Hosseiny

2,769
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19

When i import `Handler()` method android studio has 2 section one of them `android.os` and the other `java.util.logging` what is the difference – life4 Feb 05 '20 at 19:20
I choose android.os it works i understand code . This was very helpful thanks a lot :) – life4 Feb 05 '20 at 19:29

score 1 · Accepted Answer · edited Feb 08 '20 at 08:40

A fun coroutines answer:

    var loop = true
    GlobalScope.launch(Dispatchers.IO) {
        while(loop) {
            delay(TimeUnit.SECONDS.toMillis(Random.nextLong(5)))
            withContext(Dispatchers.Main) {
                when (Random.nextBoolean()) {
                    true -> background.setBackgroundColor(Color.GREEN)
                    false -> background.setBackgroundColor(Color.RED)
                }
            }
        }
    }

This will change the color randomly between the two colors, with a random interval of 1-5 seconds.

You need the dependency in your build.gradle:

dependencies {
         implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.3"
         implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.3.3'   
    }

Control the loop value to start and stop the randomisation. (perhaps in onResume & onPause.

You could make it choose random colors also using:

 background.setBackgroundColor(Random.nextInt(255))

I don't understand`GlobalScope.launch(Dispatchers.IO)` GlobalScope and Dispatchers are unresolved reference what should i do ? — life4, Feb 05 '20 at 19:08
@life4 updated it with the kotlin coroutines dependency you need to add :-) — Blundell, Feb 05 '20 at 19:27

score 0 · Answer 3 · answered Feb 04 '20 at 22:04

you can add CheckBox when checked add green Background if not add red

btn_touch.setOnCheckedChangeListener(CompoundButton.OnCheckedChangeListener
        { compoundButton, ischecked ->
            if (ischecked) {
            background.setBackgroundColor(Color.GREEN)
            } else{
            background.setBackgroundColor(Color.RED)

              }
        })

but if you want to add random every press give you Different color you can follow this question. Android: Set Random colour background on create

I hope it will help you .

sorry i don't wanna using checkbox i want to change background color random time. — life4, Feb 05 '20 at 19:22

How can I change background with random time?

3 Answers3

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