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Editorial Team
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Asked: 2026-06-05T04:21:59+00:00

I have a button that when you click it, it turns on a WakeLock,

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I have a button that when you click it, it turns on a WakeLock, and that works fine! But when you click it again its suppose to turn WakeLock off, but instead it just crashes the app! Any help would be appreciates, and I know its not because I’m changing images, because that part works fine! 🙂 Heres my code:

PowerManager.WakeLock wl; //This is before my oncreate
int stayAwake = 0; //This is before my oncreate

   ((Button) findViewById(R.id.sleepLock)).setOnClickListener(new View.OnClickListener() {

    @Override
    public void onClick(View v) {
    PowerManager pm = (PowerManager) getSystemService (Context.POWER_SERVICE); 
    wl = pm.newWakeLock (PowerManager.FULL_WAKE_LOCK, "My Tag"); 
        if (stayAwake == 0) {
        ((Button) findViewById(R.id.sleepLock)).setBackgroundResource(R.drawable.awake);
        stayAwake = 1;
        wl.acquire();
        }else {
            ((Button) findViewById(R.id.sleepLock)).setBackgroundResource(R.drawable.sleep);
            stayAwake = 0;
            wl.release();
        }

        // TODO Auto-generated method stub

    }
});

Logcat:

06-06 00:44:25.206: W/dalvikvm(3855): threadid=1: thread exiting with uncaught exception (group=0x40a031f8)
06-06 00:44:25.230: E/AndroidRuntime(3855): FATAL EXCEPTION: main
06-06 00:44:25.230: E/AndroidRuntime(3855): java.lang.RuntimeException: WakeLock under-locked My Tag
06-06 00:44:25.230: E/AndroidRuntime(3855):     at android.os.PowerManager$WakeLock.release(PowerManager.java:325)
06-06 00:44:25.230: E/AndroidRuntime(3855):     at android.os.PowerManager$WakeLock.release(PowerManager.java:300)
06-06 00:44:25.230: E/AndroidRuntime(3855):     at com.something.something.SavedGame$5.onClick(SavedGame.java:259)
06-06 00:44:25.230: E/AndroidRuntime(3855):     at android.view.View.performClick(View.java:3511)
06-06 00:44:25.230: E/AndroidRuntime(3855):     at android.view.View$PerformClick.run(View.java:14105)
06-06 00:44:25.230: E/AndroidRuntime(3855):     at android.os.Handler.handleCallback(Handler.java:605)
06-06 00:44:25.230: E/AndroidRuntime(3855):     at android.os.Handler.dispatchMessage(Handler.java:92)
06-06 00:44:25.230: E/AndroidRuntime(3855):     at android.os.Looper.loop(Looper.java:137)
06-06 00:44:25.230: E/AndroidRuntime(3855):     at android.app.ActivityThread.main(ActivityThread.java:4424)
06-06 00:44:25.230: E/AndroidRuntime(3855):     at java.lang.reflect.Method.invokeNative(Native Method)
06-06 00:44:25.230: E/AndroidRuntime(3855):     at java.lang.reflect.Method.invoke(Method.java:511)
06-06 00:44:25.230: E/AndroidRuntime(3855):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
06-06 00:44:25.230: E/AndroidRuntime(3855):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554)
06-06 00:44:25.230: E/AndroidRuntime(3855):     at dalvik.system.NativeStart.main(Native Method)
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1 Answer

  1. Editorial Team

    While you are releasing lock your button does not have any reference as you are again reinitialize button and does not set clickListener

    Change your code

    Button btn=(Button) findViewById(R.id.sleepLock);
PowerManager.WakeLock wl; //This is before my oncreate
int stayAwake = 0; //This is before my oncreate

btn.setOnClickListener(new View.OnClickListener() {

    @Override
    public void onClick(View v) {
        PowerManager pm = (PowerManager) getSystemService (Context.POWER_SERVICE); 
        wl = pm.newWakeLock (PowerManager.FULL_WAKE_LOCK, "My Tag"); 
        if (stayAwake == 0) {
            btn.setBackgroundResource(R.drawable.awake);
            stayAwake = 1;
            wl.acquire();
        } else {
            btn.setBackgroundResource(R.drawable.sleep);
            stayAwake = 0;
            wl.release();
        }
    }
});

    Now your code will work fine

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