android - 在 RecyclerView 中使用 Activity

Question

嗨，我希望用户asynctask在类中扩展RecyclerView在onPreExecute我应该使用一个 Activity viewDialog = new ViewDialog( )；但我不知道应该用什么我的代码是:

public class MainCatRecycleAdapter extends RecyclerView.Adapter<viewholder> {

 ArrayList<MainCatRecycleInfo> mainCatRecycleInfos = new ArrayList<>();

 public MainCatRecycleAdapter(ArrayList<MainCatRecycleInfo> mainCatRecycleInfos) {
    this.mainCatRecycleInfos = mainCatRecycleInfos;
 }

 @Override
 public viewholder onCreateViewHolder(ViewGroup parent, int i) {
    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.main_cat_recycle_product, parent, false);
    return new viewholder(view);
 }

 @Override
 public void onBindViewHolder(@NonNull viewholder holder, int position) {
    MainCatRecycleInfo mainCatRecycleInfo = mainCatRecycleInfos.get(position);
    holder.txtname.setText(mainCatRecycleInfo.name);

    Picasso.with(G.Context).load(Paramater.pic + "maincatimage/" + mainCatRecycleInfo.image).into(holder.img);
    Log.i("dsfsd", Paramater.pic + "maincatimage/" + mainCatRecycleInfo.image);

    holder.id = mainCatRecycleInfo.id;
 }

 @Override
 public int getItemCount() {
    return mainCatRecycleInfos.size();
 }
}


class viewholder extends RecyclerView.ViewHolder {
ViewDialog viewDialog;

public ImageView img;
public TextView txtname;
public String id = "";
public LinearLayout linearLayout;
Runnable r;

public viewholder(View itemView) {
    super(itemView);
    img = (ImageView) itemView.findViewById(R.id.mainimgrecycle);
    txtname = (TextView) itemView.findViewById(R.id.maintextrcycle);
    linearLayout = (LinearLayout) itemView.findViewById(R.id.linearrecycle);
    linearLayout.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            new AsyncTaskShowSubCats(Paramater.ip + "showSubCat.php",id).execute();

        }
    });
}



public class AsyncTaskShowSubCats extends AsyncTask {


    public String link = "";
    public String id="";


    public AsyncTaskShowSubCats(String link, String id) {
        this.link = link;
        this.id = id;

    }

    @Override
    protected Object doInBackground(Object[] objects) {
        try {
            String data = URLEncoder.encode("id", "utf-8") + "=" + URLEncoder.encode(id, "utf-8");


            URL url = new URL(link);
            URLConnection connection = url.openConnection();
            connection.setDoOutput(true);
            OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream());
            writer.write(data);
            writer.flush();


            BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            StringBuilder builder = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                builder.append(line);

            }
            ActivitySubCat.subcat = builder.toString();
            ActivitySerch.serch = builder.toString();

            Log.i("fdffs",builder.toString());



        } catch (Exception e) {

        }
        return "";
    }     

    @Override
    protected void onPreExecute() {

        viewDialog = new ViewDialog();

        viewDialog.showDialog();

        super.onPreExecute();
    }

    @Override
    protected void onPostExecute(Object o) {
            viewDialog.hideDialog();
            super.onPostExecute(o);
    }
  }
}

Answer 1

要获取 Activity 的上下文，您可以通过适配器的构造函数传递上下文。像这样的事情:

public class MainCatRecycleAdapter extends RecyclerView.Adapter<viewholder> {

 ArrayList<MainCatRecycleInfo> mainCatRecycleInfos = new ArrayList<>();
 private Context context;

 public MainCatRecycleAdapter(ArrayList<MainCatRecycleInfo> mainCatRecycleInfos, Context context) {
    this.mainCatRecycleInfos = mainCatRecycleInfos;
    this.context = context;
 }
}