Question

I am working on a flashlight android app, which has an option for screen light(Max Brightness). How can I set an activity brightness to max with a button press?

Answer 1

This site has some information about the topic: http://www.tutorialforandroid.com/2009/01/changing-screen-brightness.html

The part what you need:

IHardwareService hardware = IHardwareService.Stub.asInterface(ServiceManager.getService("hardware"));
if (hardware != null)
        hardware.setScreenBacklight(brightness);

I didn’t test it but it should work

UPDATE:
Alternate solution:

WindowManager.LayoutParams params = getWindow().getAttributes();
params.screenBrightness = 1.0f;
getWindow().setAttributes(params);