Fragment onKeyPress to listen onBackPress of attached Activity

ExitFragment.java

    private void exitFragment(View v) {
        //position click detail view in viewpager
        int position = (int) v.getTag();
        //go back to pre layout'position of this detail view(mean original view)
        runExitAnimation(v);
        ((PhotoView)v).animateTo(imageInfos.get(position), new Runnable() {
            @Override
            public void run() {
                if (!ViewPagerFragment.this.isResumed()) {//fragment be destroyed or onPaused.
                    return;
                }
                final FragmentManager fragmentManager = getFragmentManager();
                if (fragmentManager != null) {
                    fragmentManager.popBackStack();//let fragment popBackstack
                }
            }
        });
    }


    private View.OnKeyListener pressKeyListener = new View.OnKeyListener() {
        @Override
        public boolean onKey(View v, int keyCode, KeyEvent event) {
            if (keyCode == KeyEvent.KEYCODE_BACK) {//只监听返回键
                if (event.getAction() != KeyEvent.ACTION_UP) {
                    return true;
                }
                exitFragment(v);
                return true;
            }
            return false;
        }
    };

//NOTE:this is important to let the view get the focal point
                view.setFocusableInTouchMode(true);
                view.requestFocus();
                view.setOnKeyListener(pressKeyListener);//add key listener to listen back press

int position = (int) v.getTag() Why cast from object to int?