如何将Context从Adapter传递给Fragment？ （Android）[重复]

Question

这个问题在这里已有答案：

• How to use get getApplicationContext() in Adapter Class 3回答

美好的一天，

所以我一直试图解决这个问题几天了。问题是我正在使用片段和recyclerview + cardview +适配器。

我试图将Context从我的适配器传递给我的片段。我的Adapter类中有一个onClickMethod（），它从片段中启动一个新活动并显示一堆数据。

我得到的错误是：错误：不兼容的类型：AuthorsFragment无法转换为Context。

我知道问题是什么，我知道一个活动本身就是一个上下文。但是，片段不是。这很难。

适配器代码：

public class exampleAuthorsAdapter extends RecyclerView.Adapter<exampleAuthorsAdapter.MyViewHolder> {

public Context mContext;
private ArrayList<exampleItemAuthors> mExampleListAuthors;

public static class MyViewHolder extends RecyclerView.ViewHolder {

    TextView authorTitle;
    ImageView authorThumbnail;
    CardView cardview;

    public MyViewHolder(View itemView) {
        super(itemView);

        authorTitle = itemView.findViewById(R.id.authorCardViewTitle);
        authorThumbnail = itemView.findViewById(R.id.authorCardViewImage);
        cardview = itemView.findViewById(R.id.cardViewMainAuthors);
    }
}

public exampleAuthorsAdapter(Context mContext, ArrayList<exampleItemAuthors> exampleItemAuthors) {

    mExampleListAuthors = exampleItemAuthors;
    this.mContext = mContext;

}

@NonNull
@Override
public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

    View view;
    LayoutInflater mInflater = LayoutInflater.from(mContext);
    view = mInflater.inflate(R.layout.example_item_authors, parent, false);
    return new MyViewHolder(view);
}

@Override
public void onBindViewHolder(@NonNull MyViewHolder holder, final int position) {

    exampleItemAuthors currentItem = mExampleListAuthors.get(position);
    final Context mContext = holder.itemView.getContext();

    holder.authorTitle.setText(currentItem.getAuthorTitle());
    holder.authorThumbnail.setImageResource(currentItem.getAuthorThumbnail());
    holder.cardview.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent intent = new Intent(mContext, activityAuthorsView.class);
            intent.putExtra("Title", mExampleListAuthors.get(position).getAuthorTitle());
            intent.putExtra("Description", mExampleListAuthors.get(position).getAthorDescription());
            intent.putExtra("Thumbnail", mExampleListAuthors.get(position).getAuthorThumbnail());
            mContext.startActivity(intent);
        }
    });
}

@Override
public int getItemCount() {

    return mExampleListAuthors.size();

}

}

片段代码：

public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_authors, container, false);

    mLayoutManagerAuthor = new GridLayoutManager(getActivity(), 2);

    return view;
}

public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

    ArrayList<exampleItemAuthors> listAuthors = new ArrayList<>();
    listAuthors.add(new exampleItemAuthors("Niccolo Machiavelli", "The life 
    of a great human being.", R.drawable.machiavelli));

    mRecyclerViewAuthor = view.findViewById(R.id.recyclerViewAuthor);
    mRecyclerViewAuthor.setHasFixedSize(true);
    mAdapterAuthor = new exampleAuthorsAdapter(this, getActivity());
    mRecyclerViewAuthor.setLayoutManager(mLayoutManagerAuthor);
    mRecyclerViewAuthor.setAdapter(mAdapterAuthor);

任何和所有的帮助都会很棒!!!我在苦苦挣扎:(（（（（（（

Answer 1

这是你的适配器构造函数：

public exampleAuthorsAdapter(Context mContext, ArrayList<exampleItemAuthors> exampleItemAuthors) {

this.mExampleListAuthors = exampleItemAuthors;
this.mContext = mContext;

}

在这里，您可以在片段中创建一个新的适配器：

 mAdapterAuthor = new exampleAuthorsAdapter(this, getActivity()); //won't work

我们看到你的第一个参数必须是上下文（getActivity）而第二个参数是数据（ArrayList listAuthors），所以更改适配器初始化raw如下：

 mAdapterAuthor = new exampleAuthorsAdapter(getActivity(), listAuthors);

请享用！