How to get an Android WakeLock to work?

user_41742 0
Viewed 137199

My WakeLock isn't keeping my device awake.

In OnCreate() I've got:

PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
mWakeLock = pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK | PowerManager.ON_AFTER_RELEASE, "My Tag");
mWakeLock.acquire();

then:

new CountDownTimer(1320000, 200) {

    public void onTick(long millisUntilFinished) {
        // I update a progress bar here.                                         
    }

    public void onFinish() {
        // I finish updating the progress bar.
        mWakeLock.release();
    }
}.start();

The screen turns off before the timer finishes, how can I make the screen stay visible?

mWakeLock is a field previously declared like so:

private PowerManager.WakeLock mWakeLock;

My device uses Android 1.6. I would really appreciate any help to resolve this.

android
14 Answers

Do you have the required permission set in your Manifest?

<uses-permission android:name="android.permission.WAKE_LOCK" />
user_1482390

I am having a similar problem. I can get the screen to stay on, but if I use a partial wake lock and the screen is turned off, my onFinish function isn't called until the screen is turned on.

You can check your wake lock using mWakeLock.isHeld(), first of all, to make sure you're getting it. Easiest way is to add that to the code, set a breakpoint on it in the debugger, and then check it.

In my case, I'm getting it, but the partial wake lock doesn't seem to be doing anything. Here's my working code for the screen dim lock.

protected void setScreenLock(boolean on){
        if(mWakeLock == null){
            PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
            mWakeLock = pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK |
                                        PowerManager.ON_AFTER_RELEASE, TAG);
        }
        if(on){
         mWakeLock.acquire();
        }else{
            if(mWakeLock.isHeld()){
                mWakeLock.release();
            }
         mWakeLock = null;
        }

    }

ADDENDUM:

Droid Eris and DROID users are reporting to me that this DOES NOT work on their devices, though it works fine on my G1. What device are you testing on? I think this may be an Android bug.

user_2627290

If your use-case is making the screen (activity) ON while doing an action, you shouldn't use WakeLock.

The best way to do that is by enabling the flag FLAG_KEEP_SCREEN_ON.

You can do it programmatically:

class MainActivity : Activity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        window.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
    }
}

Or in your application's layout XML file, by using the android:keepScreenOn attribute:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:keepScreenOn="true">
    ...
</RelativeLayout>

Keep the screen on

If that's not the case, check these alternative solutions according to your use-case Alternatives to using wake locks

user_22564070
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