为什么我的上下文滑行返回错误在logcat中可以为空？

Question

我是使用滑翔的新手。我尝试从外部存储加载图像，但我在logcat中出错：

我的循环视图适配器类使用滑动来加载图像：

List<TourModel> mItems;
    private Context mContext;

    public class ViewHolder extends RecyclerView.ViewHolder{
        public ImageView mIvMain,mIvStar1,mIvStar2,mIvStar3,mIvStar4,mIvStar5;
        public TextView mTvTitle,mTvPrice;
        public RelativeLayout mLayoutContainer;
        public ViewHolder(View mItemView) {
            super(mItemView);
            mIvMain = (ImageView) mItemView.findViewById(R.id.listFragmentMain_IvMain);
            mIvStar1= (ImageView) mItemView.findViewById(R.id.listFragmentMain_IvStar1);
            mIvStar2= (ImageView) mItemView.findViewById(R.id.listFragmentMain_IvStar2);
            mIvStar3= (ImageView) mItemView.findViewById(R.id.listFragmentMain_IvStar3);
            mIvStar4= (ImageView) mItemView.findViewById(R.id.listFragmentMain_IvStar4);
            mIvStar5= (ImageView) mItemView.findViewById(R.id.listFragmentMain_IvStar5);
            mTvTitle = (TextView) mItemView.findViewById(R.id.listFragmentMain_TvTitle);
            mTvPrice = (TextView) mItemView.findViewById(R.id.listFragmentMain_TvPrice);
            mLayoutContainer = (RelativeLayout)mItemView.findViewById(R.id.listFragmentMain_LayoutContainer);
        }
    }

    public TourListRvAdapter(Context mContext,List<TourModel> mModel) {
        this.mItems = mModel;
        this.mContext = mContext;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup mViewGroup, int i) {
        View mView = LayoutInflater.from(mViewGroup.getContext()).inflate(R.layout.list_fragment_main, mViewGroup, false);
        ViewHolder mViewHold = new ViewHolder(mView);
        return mViewHold;
    }

    @Override
    public void onBindViewHolder(ViewHolder mViewHolder, int position) {
        final TourModel mItems=this.mItems.get(position);
        mViewHolder.mTvTitle.setText(mItems.getTitle());
        mViewHolder.mTvPrice.setText(mItems.getPrice() + "");

        Glide.with(mContext)
                .load(Utility.LoadFileImg(mItems.getImage()))
                .into(mViewHolder.mIvMain);
    }

并且我的片段活动调用了recycleview适配器并向其添加了变量上下文。

Public class TourListFragment extends Fragment {
    private static final String TAG = TourListFragment.class.getSimpleName();
    private final Context mContext = getActivity();

    private int position;
    private List<TourModel> mListItem;

    private RecyclerView mRecycleView;

    private TourListRvAdapter mTouListAdapter;

    public static TourListFragment newInstance(int position) {
        TourListFragment f = new TourListFragment();
        Bundle b = new Bundle();
        b.putInt(VariableConstants.POSITION, position);
        f.setArguments(b);
        return f;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        position = getArguments().getInt(VariableConstants.POSITION);
        TourDAO mDao = new TourDAO(getContext());
        mListItem = mDao.getAllDataReturnModel();

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        Log.e(TAG, "" + position);

            View rootView = inflater.inflate(R.layout.fragment_main, container, false);

            mRecycleView = (RecyclerView) rootView.findViewById(R.id.fragmentMain_RvTourList);
            mRecycleView .setHasFixedSize(true); // in content do not change the layout size of the RecyclerView
            RecyclerView.LayoutManager mLayoutManager= new LinearLayoutManager(mContext); // use a linear layout manager
            mRecycleView.setLayoutManager(mLayoutManager);

            mTouListAdapter = new TourListRvAdapter(mContext,mListItem);
            mRecycleView.setAdapter(mTouListAdapter);

            //iewCompat.setElevation(rootView, 50);
            return rootView;

    }
}

我不知道为什么我的变量mContext返回null，任何人都可以帮助我？请。

Answer 1

使用mViewHolder.itemView.getContext()，这是您在onCreateViewHolder中使用的相同上下文来扩充视图，而不是在适配器中保留引用。 mContext为null，因为您正在初始化成员

private final Context mContext = getActivity();

Fragment当时没有经历其生命周期，getActivity（）返回null