Android: Listen for power key press

Question

I am currently trying to listen for when the power button is pressed. Ultimately I would like to have some code run when the power button is pressed twice, to check whether the screen is locked or unlocked. I currently have this:

  @Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    getWindow().addFlags(WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD);//prevent phone from being locked
}

@Override 
public boolean onKeyDown(int keyCode, KeyEvent event) {

    switch (keyCode) {
        case KeyEvent.KEYCODE_POWER:
        {
            Toast.makeText(getBaseContext(), "Power button pressed", Toast.LENGTH_LONG).show();

            return true;
        }
        case KeyEvent.KEYCODE_MENU:
            Toast.makeText(getBaseContext(), "Menu Button Pressed", Toast.LENGTH_LONG).show();

            return true;
    }
    return super.onKeyDown(keyCode, event);
}

The code works fine to toast for the menu keyevent but doesn't do anything for the power key event. Any ideas?

Debate

There is no API for this but you can achieve it using reflection. https://mcmap.net/q/82478/-how-to-capture-app-switch-key-using-onkeydown-in-android – Bruce

Answer 1

Although I couldn't capture the hardware key I ended up being able guess that the power key was pressed by using a broadcast receiver that listens for whether the screen is turned off or on. I used:

            if (intent.getAction().equals(Intent.ACTION_SCREEN_OFF)) {
                    //do something 
            }

            else if (intent.getAction().equals(Intent.ACTION_SCREEN_ON)) {
                    //do something else
            }

I was able to be more sure that the power button was being pressed by having a count that would timeout after a couple second. This way I have the user press the power button three times to ensure that proper behavior.

Debate

hey, AFAIK, this intent is broadcasted after the event has occurred, is it what you want ? – Belmonte

This intent is broadcasted ~ a second or two later, has someone experienced this? – Nye

Answer 2

AFAIK, it's not possible for Power key.

You might want to refer to this answer: http://groups.google.com/group/android-developers/browse_thread/thread/a4db4def1bdaa8d9

Membranous

Answer 3

I've used android-annotations "@Receiver" annotation.

Add this to your "@EActivity" annotated Activity:

@Receiver(actions = Intent.ACTION_SCREEN_OFF)
protected void onPowerButtonPressed() {
// add your code
}

Carline