Android: How to turn screen on and off programmatically?
params.flags |= LayoutParams.FLAG_KEEP_SCREEN_ON;
params.screenBrightness = 0;
getWindow().setAttributes(params);

params.flags |= LayoutParams.FLAG_KEEP_SCREEN_ON;
params.screenBrightness = -1f;
getWindow().setAttributes(params);

PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK, "tag");
    wl.acquire();

getWindow().addFlags(WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);

params.flags |= LayoutParams.FLAG_KEEP_SCREEN_ON;
params.screenBrightness = 0;
getWindow().setAttributes(params);

WindowManager.LayoutParams params = getWindow().getAttributes();
params.screenBrightness = -1;
getWindow().setAttributes(params);

WindowManager.LayoutParams params = getWindow().getAttributes();
params.screenBrightness = 1;
getWindow().setAttributes(params);

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

private void unlockScreen() {
        Window window = this.getWindow();
        window.addFlags(LayoutParams.FLAG_DISMISS_KEYGUARD);
        window.addFlags(LayoutParams.FLAG_SHOW_WHEN_LOCKED);
        window.addFlags(LayoutParams.FLAG_TURN_SCREEN_ON);
    }

Calling hidden API in android to turn screen off

PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP, "tag");
wl.acquire();