Question

I have created some extended UI controls based on the default android widgets (Button, ProgressBar). At some point, in the custom control, I want to communicate with the view that contains the custom control. For example, I want to pass the current value of the ProgressBar or a value from the Button.
What is the best approach? Is it possible to create a custom event (like the “onClick”) and then have in the container class an handler? Or there is some better approach?
Thank you in advance! 😉

Answer 1

If the “some point” is when an event happens (like when you press the button) you can create an event listener interface.

Inside a custom view of mine I put this:

    private OnFlingListener flingListener;

    // my event listener interface
    public interface OnFlingListener {
        public abstract boolean onFling(View v, int direction);
    }

    public void setOnFlingListener(OnFlingListener l) {
        flingListener = l;
    }

    // ........my custom view code.......

    // event handling now
    private void flingRight() {
        if(flingListener != null) {
            if(flingListener.onFling(this, FLING_TO_RIGHT))
                showPrevious();
        } else {
            showPrevious();
        }
    }

this way I can implement OnFlingListener as I would do with OnClickListener.

EDIT:

my onFling returns a boolean because I wanted to decide in there if to accept or cancel the event (see flingRight()). It could also return void.