etxt_my.setOnKeyListener( new OnKeyListener(){

    public boolean onKey(View v, int keyCode, KeyEvent event) {
        if(event.getAction()==KeyEvent.ACTION_DOWN)
        {
            if(keyCode==KeyEvent.KEYCODE_DPAD_CENTER) {
                aList.add(0, etxt_my.getText().toString());
                aA.notifyDataSetChanged();
                etxt_my.setText("");
                return true;
            }
        }
        return false;
    }
});