在 RecyclerView Adapter 上滑行，当我尝试将 Fragment 放入 Activity 时，应用程序崩溃了

Question

我有一个 Fragment 到一个 Activity，我在那里显示来自 RecyclerView 的数据。当我单击一个按钮时，它会将我转到 Activity。在 Adapter 中，我想尝试 Glide 获取图标，但问题是 Glide 它正在使应用程序崩溃。如果我用 setImageResource 手动添加一个图标，它不会使应用程序崩溃，但我想用 Glide 添加，因为图标取决于 url.

这是代码。

Adapter.class

    public class ReadingListAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private Context mContext;
ArrayList<ReadingList> arrayList;
ReadingListDB readingListDB;
String BASE_URL = "https://www.google.com/s2/favicons?domain=";


public ReadingListAdapter(Context mContext, ArrayList<ReadingList> arrayList) {
    this.mContext = mContext;
    this.arrayList = arrayList;

}

@NonNull
@Override
public ReadingListAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
    View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.reading_item, viewGroup, false);
    return new ViewHolder(view);
}


@Override
public void onBindViewHolder(@NonNull final RecyclerView.ViewHolder holder, final int i) {
    final ViewHolder viewHolder = (ViewHolder) holder;
    readingListDB = new ReadingListDB(mContext);

    viewHolder.readingListTitle.setText(arrayList.get(i).getPageTitle());
    viewHolder.readingListUrl.setText(arrayList.get(i).getUrl());
    String imageURL = BASE_URL + arrayList.get(i).getUrl();
    viewHolder.imgFavIcon.setImageResource(R.drawable.default_favicon); //Here is the set manually


    Glide.with(mContext)
            .load(imageURL)
            .into(viewHolder.imgFavIcon);

Activity.class

public class ActivityBookmarksFavorites extends AppCompatActivity implements View.OnClickListener {
    private static final String TAG = "ActivityBookmark";
    Button btnChangeBookmark, speedDial, readingList;
    LinearLayout addBookmarkLayout;
    ImageView addBookmark;
    BookmarkDB bookmarkDB;
    String data = null;
    Button btnClose;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_bookmarks);
        speedDial = findViewById(R.id.btnFavSites);
        readingList = findViewById(R.id.btnFavPages);

        bookmarkDB = new BookmarkDB(this);
        Intent receivedIntent = getIntent();
        String test = receivedIntent.getStringExtra("SpeedDial");
        SpeedDialFragment newFragment = new SpeedDialFragment();
        ReadingListFragment newFragment2 = new ReadingListFragment();
        if ("SpeedDial".equals(test)) {
            getSupportFragmentManager().beginTransaction().add(R.id.frameLayoutWithFragment, newFragment).commit();
            speedDial.setSelected(true);
            speedDial.setClickable(true);
        } else {
            getSupportFragmentManager().beginTransaction().add(R.id.frameLayoutWithFragment, newFragment2).commit();
            readingList.setSelected(true);
            readingList.setClickable(true);
        }

Fragment.class

public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        paramView = inflater.inflate(R.layout.fragment_reading_list, container, false);
        linLayoutEmptyLis = paramView.findViewById(R.id.linLayoutEmptyListReading);
        mRecyclerView = paramView.findViewById(R.id.lvReading);
        readingListAdapter = new ReadingListAdapter(mContext, arrayList);
        readingListDB = new ReadingListDB(getActivity());
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(mContext);
        mRecyclerView.setLayoutManager(linearLayoutManager);
        mRecyclerView.setHasFixedSize(true);
        ReadingList readingList = new ReadingList();
        DividerItemDecoration mDividerItemDecoration = new DividerItemDecoration(mRecyclerView.getContext(),
                linearLayoutManager.getOrientation());
        mRecyclerView.addItemDecoration(mDividerItemDecoration);
        new ItemTouchHelper(itemTouchHelperCallback).attachToRecyclerView(mRecyclerView);
        final Cursor data = readingListDB.getData();

单击并发送到 Activity 的按钮。
MainActivity.class

 bookmark.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this, ActivityBookmarksFavorites.class);
                startActivity(intent);
            }
        });

Glide 出错

You cannot start a load on a not yet attached View or a Fragment where getActivity() returns null (which usually occurs when getActivity() is called before the Fragment is attached or after the Fragment is destroyed)

Answer 1

您在 Fragment.class 的 onCreateView 的第 4 行中使用了未初始化的变量 (mContext)。只需在之前初始化它或调用 getActivity() 以提供有效的上下文。

在 RecyclerView Adapter 上滑行，当我尝试将 Fragment 放入 Activity 时，应用程序崩溃了

Glide at RecyclerViewAdapter it is crashing the app when I try to see a Fragment into an Activity

android

android-fragments

android-glide