Question

我Fragment设置了RecyclerView。在片段上按Button后，我转到下一个片段。再次onBackPressed后，我来到片段前面。这个时间全部Reycycler View中的项目是Doubled 这是在Fragment中设置Recyclerview的代码。

JsonArrayRequest req = new JsonArrayRequest(Request.Method.GET, url, null,
                new Response.Listener<JSONArray>() {
                    @Override
                    public void onResponse(JSONArray response) {
                        try
                        {
                            for( int i=0;i<response.length();i++)
                            {
                                JSONObject obj = response.getJSONObject(i);
                                final BookEntry tableEntry=new BookEntry();
                                String status=obj.getString("status");
                                if(status.equals("F"))
                                {
                                    Entry.setName(obj.getString("name"));
                                  Entry.setDescription(obj.getString("description"));
                                   Entry.setCapacity(obj.getString("capacity"));
                                    Entry.setId(obj.getString("id"));
                                    current.add(tableEntry);
                                    adapter=new BookingAdapter(current,getActivity().getApplicationContext());
                                    recyclerView.setAdapter(adapter);
                                    adapter.notifyDataSetChanged();
                                }
                            }

                        }
                        catch (JSONException e)
                        {
                            e.printStackTrace();
                        }

                    }

这是适配器

的代码

public class TableBookingAdapter extends RecyclerView.Adapter<BookingAdapter.ViewHolder> {
    private ArrayList<BookEntry> entry;
    Context context;
        String id;
    public BookingAdapter(ArrayList<BookEntry> entry, Context context) {
        this.entry = entry;
        this.context = context;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.booking_card, parent, false);
        return new ViewHolder(v);
    }

    @Override
    public void onBindViewHolder(final ViewHolder holder, final int position) {
        final BookEntry currentEntry = entry.get(position);
        holder.name.setText(currentEntry.getName());
        holder.description.setText(currentEntry.getDescription());
        holder.capacity.setText(currentEntry.getCapacity());
        holder.tableId.setText(currentEntry.getId());
    }

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

    public class ViewHolder extends RecyclerView.ViewHolder {
        TextView name, description, capacity,tableId;
    final     CheckBox check;
        public ViewHolder(final View itemView) {
            super(itemView);
            name = (TextView) itemView.findViewById(R.id.name);
            description = (TextView) itemView.findViewById(R.id.description);
            capacity = (TextView) itemView.findViewById(R.id.capacity);
            tableId=(TextView)itemView.findViewById(R.id.tableId);
            check=(CheckBox)itemView.findViewById(R.id.book);
        }
    }
}

如何防止项目重复？

Answer 1

在json解析之前清除数组列表。我正在编辑你的代码。只需添加一行。

if(current!=null && current.size()>0){
   current.clear();
}


JsonArrayRequest req = new JsonArrayRequest(Request.Method.GET, url, null,
                new Response.Listener<JSONArray>() {
                    @Override
                    public void onResponse(JSONArray response) {
                        try
                        {
                            for( int i=0;i<response.length();i++)
                            {
                                JSONObject obj = response.getJSONObject(i);
                                final BookEntry tableEntry=new BookEntry();
                                String status=obj.getString("status");
                                if(status.equals("F"))
                                {
                                    Entry.setName(obj.getString("name"));
                                  Entry.setDescription(obj.getString("description"));
                                   Entry.setCapacity(obj.getString("capacity"));
                                    Entry.setId(obj.getString("id"));
                                    current.add(tableEntry);
                                    adapter=new BookingAdapter(current,getActivity().getApplicationContext());
                                    recyclerView.setAdapter(adapter);
                                    adapter.notifyDataSetChanged();
                                }
                            }

                        }
                        catch (JSONException e)
                        {
                            e.printStackTrace();
                        }

                    }

如何防止RecyclerView项目重复onBack按下并进入Fragment设置RecyclerView

1 个答案: