Taking over the volume key on Android

Question

I want to take overinput over the Volume Up and Down. At the moment my code is:

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

    Log.v(TAG, event.toString());
    if (keyCode == KeyEvent.KEYCODE_VOLUME_DOWN){
        mLamp.moveBackward();

        return false;
    }
    else if(keyCode == KeyEvent.KEYCODE_VOLUME_UP){
        mLamp.moveForward();

        return false;
    }

    return true;
}
public boolean onKeyUp(int keyCode, KeyEvent event) {

    Log.v(TAG, event.toString());
    if (keyCode == KeyEvent.KEYCODE_VOLUME_DOWN){
        return false;
    }
    else if(keyCode == KeyEvent.KEYCODE_VOLUME_UP){
        return false;
    }

    return true;
}

This triggers the mLamp.moveBackward() and mLamp.moveForward() function but it still changes the volume of the ringer. What do I have to do that the ringer loudness doesn't change?

score 20 · Accepted Answer · edited Oct 26 '13 at 10:09

20

If you handled the event, return true. If you want to allow the event to be handled by the next receiver, return false.

edited Oct 26 '13 at 10:09

Adil Shaikh

44,509
17
89
111

answered Jul 10 '10 at 19:34

zed_0xff

32,417
7
53
72

simple and efficient answer. that is how it should be. thanks. – mad Jan 30 '11 at 09:26
1

The answer by vod23 is essential to keep other buttons working. – Nino van Hooff Mar 05 '13 at 12:22

score 9 · Answer 2 · answered Oct 09 '12 at 06:33

It's important to return true if you handled the event, but if you didn't handle the event, it's good to make sure that the event is still handled by the superclass. Here's some code from my app:

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_VOLUME_DOWN ||
        keyCode == KeyEvent.KEYCODE_VOLUME_UP) {
        changeColor(keyCode);

        return true;
    }

    return super.onKeyDown(keyCode, event);
}

@Override
public boolean onKeyUp(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_VOLUME_DOWN ||
        keyCode == KeyEvent.KEYCODE_VOLUME_UP) {
        // do nothing                                                       

        return true;
    }

    return super.onKeyUp(keyCode, event);
}

In my case, the superclass call was necessary so that other hardware buttons on my device continued to work.

score -2 · Answer 3 · answered May 17 '13 at 03:09

-2

public boolean dispatchKeyEvent(KeyEvent event) {

    if (event.getKeyCode() == KeyEvent.KEYCODE_VOLUME_UP) {             
            return true;
    } else if (event.getKeyCode() == KeyEvent.KEYCODE_VOLUME_DOWN) {
            return true;
    }
    return dispatchKeyEvent(event);
}

answered May 17 '13 at 03:09

rijoviany

5
2

2

Your final line will recursively call the method resulting in a stackoverflow or ANR whichever happens first. – William Jan 07 '15 at 21:47
The last line should call the super class's method, not itself. – grolschie Jan 07 '20 at 00:23

Taking over the volume key on Android

3 Answers3

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