Android: How to prevent а device from going to sleep?

Recongalina · March 19, 2026, 3:54pm

Hello to All!

I’m making a workout timer for Android. For such an app, it’s crucial that the screen doesn’t turn off while the counting is in progress.

So my first question is: how can I prevent the screen from turning off automatically?

And a related question: how can I keep the counting process going when the app is minimized?

phomm · March 20, 2026, 1:47am

Most probably you would need to add a new android service with specific permission

But I don’t know the exact details..

Recongalina · March 20, 2026, 2:05pm

At first glance it looks very complicated, because I don’t know either this programming language and this API at all -______-

But thanks for the tip anyway

michalis · March 21, 2026, 1:09am

Indeed, I’m afraid both tasks you ask about require Android-specific code, using Java to access Android APIs, links from @phomm answer are exactly the ones I would recommend. Mobile applications, out of the box, just don’t have such “power” by design – a regular application cannot keep your screen from turning off, and regular application may be killed at any moment by Android.

Recongalina · March 21, 2026, 5:46am

Studying this example and the CGE code, I’m starting to understand something…

What does “MyClassName::MyWakelockTag” mean on line 21?

github.com/android/snippets

misc/src/main/java/com/example/snippets/backgroundwork/WakeLockSnippetsJava.java

60ee5d9fa


      
          
          PowerManager.WakeLock wakeLock;
          final long WAKELOCK_TIMEOUT = 10*60*1000L; // 10 minutes
          
          @Override
          protected void onCreate(@Nullable Bundle savedInstanceState) {
          
              // [START android_backgroundwork_wakelock_create_java]
              PowerManager powerManager = (PowerManager) getSystemService(POWER_SERVICE);
              PowerManager.WakeLock wakeLock =
                      powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "MyClassName::MyWakelockTag");
              wakeLock.acquire(WAKELOCK_TIMEOUT);
              // [END android_backgroundwork_wakelock_create_java]
          
              super.onCreate(savedInstanceState);
          }
          
          @SuppressWarnings("unused")
          // [START android_backgroundwork_wakelock_release_java]
          void doSomethingAndRelease() throws MyException {
              try {

phomm · March 21, 2026, 9:40am

as said in the docs, it is “just” a tag, so mostly for programmer, just a convenient string for you. there is a good practice to name it based on class+methodname https://developer.android.com/develop/background-work/background-tasks/awake/wakelock/best-practices

I say “just” , bc it is somewhat used by system for logging and statistics

Recongalina · March 27, 2026, 4:35pm

Ok, I made it just a screen hold like for a video player. It doesn’t even require permission.

Here is the service I wrote:

github.com/SerufuYua/training_timer_2

android_services/keep_screen/app/src/main/java/io/castleengine/ServiceKeepScreen.java

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/* -*- tab-width: 4 -*- */

/*
  ----------------------------------------------------------------------------
*/

package io.castleengine;

import android.app.Activity;
import android.view.WindowManager;

/**
 * For this service no need special permission on Android.
 */
public class ServiceKeepScreen extends ServiceAbstract
{
    public ServiceKeepScreen(MainActivity activity)
    {
        super(activity);
    }

This file has been truncated. show original

Here is Pascal usage:

github.com/SerufuYua/training_timer_2

code/seqkeepscreenservice.pas

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          procedure KeepScreen(AEnable: Boolean);
          begin
            {$ifdef DEBUG}
            if AEnable then
              WritelnLog('keep-screen is ON')
            else
              WritelnLog('keep-screen is OFF');
            {$endif}
          
            {$if defined(ANDROID)}
            if AEnable then
              Messaging.Send(['keep-screen', 'ON'])
            else
              Messaging.Send(['keep-screen', 'OFF']);
            {$endif}
          end;
          
          end.

According to this documentation:

This functionality is already enough to make my app fully usable. And I can make the release.

PS: For Windows version added same functionality.

PS2: Background counting isn’t implemented yet, but I thinking on it.

michalis · March 27, 2026, 5:29pm

Thanks for sharing, and the service is nicely simple! I’m happy to see more people are making use of our Android services.

P.S. Ability to define Android service in a project and not need to copy it to CGE sources (to address also your notes in training_timer_2/android_services/readme.md at main · SerufuYua/training_timer_2 · GitHub ) will come. I know the current approach is not comfortable It’s part of my packages plan.