Android - Volume Buttons used in my application

I need to use volume buttons to control a variable parameter in my application. I use Activity.onKeyDown to get notified when the button is pressed but the media volume is also increased.

Android is doing somethi开发者_Go百科ng like below when I press the volume key:

1. increase media / ringtone volume
2. pass the event to my application

Is there a way to avoid increasing the system volume and use volume key only for my application?

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You need to capture all actions:

@Override
public boolean dispatchKeyEvent(KeyEvent event) {
    int action = event.getAction();
    int keyCode = event.getKeyCode();
        switch (keyCode) {
        case KeyEvent.KEYCODE_VOLUME_UP:
            if (action == KeyEvent.ACTION_DOWN) {
                //TODO
            }
            return true;
        case KeyEvent.KEYCODE_VOLUME_DOWN:
            if (action == KeyEvent.ACTION_DOWN) {
                //TODO
            }
            return true;
        default:
            return super.dispatchKeyEvent(event);
        }
    }

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The next would be better because a long click for KeyEvent.KEYCODE_VOLUME_UP does not work right in the previous answer.

@Override
public boolean dispatchKeyEvent(KeyEvent event) {
    int action = event.getAction();
    int keyCode = event.getKeyCode();
    switch (keyCode) {
        case KeyEvent.KEYCODE_VOLUME_UP:
            if (action == KeyEvent.ACTION_DOWN) {
                //TODO
            }
            return true;
        case KeyEvent.KEYCODE_VOLUME_DOWN:
            if (action == KeyEvent.ACTION_DOWN) {
                //TODO
            }
            return true;
        default:
            return super.dispatchKeyEvent(event);
    }
}

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Just to complete the previous answers, if you want long click support you should check how long the key was down using:

event.getEventTime() - event.getDownTime() > ViewConfiguration.getLongPressTimeout() 

In the end the code will look like this:

    @Override
public boolean dispatchKeyEvent(KeyEvent event) {
    int action = event.getAction();
    int keyCode = event.getKeyCode();
    switch (keyCode) {
        case KeyEvent.KEYCODE_VOLUME_UP:
            if (action == KeyEvent.ACTION_UP) {
                if (event.getEventTime() - event.getDownTime() > ViewConfiguration.getLongPressTimeout()) {
                    //TODO long click action
                } else {
                    //TODO click action
                }
            }
            return true;
        case KeyEvent.KEYCODE_VOLUME_DOWN:
            if (action == KeyEvent.ACTION_UP) {
                if (event.getEventTime() - event.getDownTime() > ViewConfiguration.getLongPressTimeout()) {
                    //TODO long click action
                } else {
                    //TODO click action
                }
            }
            return true;
        default:
            return super.dispatchKeyEvent(event);
    }
}

---

I've used this code to listen for the volume button before.

  @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if ((keyCode == KeyEvent.KEYCODE_VOLUME_DOWN)){
            //Do something
        }
        return true;
    }

---

Volume Button Usage in Fragments

If you desire to implement this in fragments bound the Activity ,you can use as:

Notice:fragment_words is just a layout name which is used arbitarly

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    View rootView = inflater.inflate(R.layout.fragment_words, container, false);
rootView.requestFocus();
    rootView.setOnKeyListener(new View.OnKeyListener() {
            @Override
            public boolean onKey(View v, int keyCode, KeyEvent event) {

                if( keyCode == KeyEvent.KEYCOD_VOLUME_DOWN ) {

                    //TODO SOMETHING
                    return true;
                } else {
                    return false;
                }
            }
        });}

---

volume with double click action

public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_VOLUME_DOWN) {
        i++;
        Handler handler= new Handler();
        Runnable runnable=new Runnable() {
            @Override
            public void run() {
                i=0;
            }
        };
        if(i==1){
            Toast.makeText(getApplicationContext(),"single click",Toast.LENGTH_SHORT).show();
            handler.postDelayed(runnable,400);
        }
        else if(i==2){
            Vibrator vb = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
            vb.vibrate(100);
        }

        return true;
    }
    if (keyCode == KeyEvent.KEYCODE_VOLUME_UP) {
        return true;
    } else {
        return super.onKeyDown(keyCode, event);
    }
}

---

i had a problem with the AB shutter (bluetooth) always launching the volume up, while i wanted to use the bluetooth keyevent for something else. but i still wanted the volume up to work when coming from the device's volume up button. the solution i found was to handle short events for my purpose - and to allow volume up change only if pressing on the device's button for over a second. see code:

boolean bVolumeUpKeyDown = false;
long StartDownMS = 0;

@Override
public boolean dispatchKeyEvent(KeyEvent event) {
    int action = event.getAction();
    int keyCode = event.getKeyCode();
    switch (keyCode) {
        case KeyEvent.KEYCODE_VOLUME_UP:
            if (action == KeyEvent.ACTION_UP) {
                // my handling of keyevent
                return true;
              }
              else if  (action == KeyEvent.ACTION_DOWN) {
                  if(bVolumeUpKeyDown == false) {
                      bVolumeUpKeyDown = true;
                      StartDownMS = System.currentTimeMillis();
                  }
                  else if(System.currentTimeMillis() - StartDownMS > 1000)
                      return super.dispatchKeyEvent(event); // normal volume up handling
            }
            return true;

       case KeyEvent.KEYCODE_ENTER:
           if (action == KeyEvent.ACTION_UP) {
           //my handling of second ab shutter button
                }
            return true;

       default:
            return super.dispatchKeyEvent(event);
    }
}