請問Fragment的ViewPager這樣的空指針該怎么結(jié)局呢?

網(wǎng)上找了其他解決方法也不行
錯誤日志:
java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.app.Activity.findViewById(int)' on a null object reference at com.dmxy.fragment.ChannelFragment.onCheckedChanged(ChannelFragment.java:226)

代碼:

  @Override
    public void onCheckedChanged(RadioGroup group, int checkedId) {
        if (json != null) {
            Gson gson = new Gson();
            ChannelGameTypeBean channelGameTypeBean = gson.fromJson(json, ChannelGameTypeBean.class);
            List<ChannelGameTypeBean.DataBean> data = channelGameTypeBean.getData();
            //TODO:三大游戲類型需改為動態(tài)加載數(shù)據(jù)
            ChannelGameTypeBean.DataBean dataBean = data.get(0);//初次獲取王者榮耀數(shù)據(jù)  1.英雄聯(lián)盟  2.王者榮耀   3.絕地求生
            List<ChannelGameTypeBean.DataBean.NavBean> nav = dataBean.getNav();
            ChannelGameTypeBean.DataBean.NavBean navBean = nav.get(checkedId);//0.比賽 1.解說   2.戰(zhàn)隊    3.專欄    4.大神
            int navId = navBean.getNavid();
            int sizes = data.size();
            String size = String.valueOf(sizes);
            //傳遞獲取分類游戲數(shù)據(jù)的POST參數(shù)
            BaseApplication.getApplication().getMap().put("navId", navId);
            BaseApplication.getApplication().getMap().put("size", size);
        }
        // TODO 臨時選中
        //TODO:首頁和頻道模塊快速切換有bug
        RadioButton tempButton = getActivity().findViewById(checkedId); // 這行空指針
        Log.d(TAG, "2222222222222");
        tempButton.setOnClickListener(this);
    }