更新片段中的RecyclerView适配器项

Question

我将Recycler View放入片段活动中，其中包含许多Card View项目 但是，当我单击“刷新”按钮时，这些项目是第一次创建的

当下次加载Fragment时，不会再次获取这些项目，而这仅是第一次进行。

public class posts_fragment extends Fragment {
    private List<PostData> PostDataList = new ArrayList<>();
    PostDataAdapter adapter=new PostDataAdapter(PostDataList);
    RecyclerView recyclerView;
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View view=inflater.inflate(R.layout.posts_menu,container,false);
        recyclerView =view.findViewById(R.id.PostRecycleView);
        filldate();
        recyclerView.setAdapter(adapter);
        recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
        return view;
    }

public void filldate() {

    //Start Get And Set Json Into Card View

    final String KeyUrl="http://www.rasamdev.ir/salehin/GetPost.php";
    final String KeyUsername="Key";
    StringRequest stringRequest = new StringRequest(Request.Method.POST, KeyUrl, new Response.Listener<String>() {
        @Override
        public void onResponse(String response) {
            Toast.makeText(getContext(),response, Toast.LENGTH_SHORT).show();
            //Start Pars
            if (response != null) {
                try {
                    JSONObject jObject = new JSONObject(response);
                    JSONArray array = jObject.getJSONArray("Posts");
                    for (int i = 0; i < array.length(); i++) {
                        JSONObject object = array.getJSONObject(i);
                        String puid = object.getString("puid");
                        String Ptitr = object.getString("Ptitr");
                        String ptext = object.getString("ptext");
                        String pdate = object.getString("pdate");
                        String plike = object.getString("plike");
                        String pview = object.getString("pview");
                        String pimg = object.getString("pimg");
                        PostDataList.add(new PostData(pdate,ptext,puid,Ptitr,pimg,pview,plike));
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }

            }

            //End Pars


        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Toast.makeText(getActivity(), error + "", Toast.LENGTH_SHORT).show();
        }
    }){

        @Override
        protected Map<String, String> getParams() {
            HashMap<String, String> hashMap = new HashMap<>();
            hashMap.put(KeyUsername,"13581358r@R");
            return hashMap;
        }

    };


    RequestQueue requestQueue= Volley.newRequestQueue(this.getActivity());
    requestQueue.add(stringRequest);

    //End
}

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


}


@Override
public void onResume() {
    adapter.notifyDataSetChanged();
    super.onResume();
}

适配器类：

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

    private List<PostData> PostDataList ;
    public static class MyViewHolder extends RecyclerView.ViewHolder {
        public TextView vPostContent, vPostDate, vPostAuthor, vPostTitr,VPostLikes,VPostViews;
        public ImageView vPostPhoto;

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

            vPostContent = v.findViewById(R.id.PostContentTv);
            vPostDate = v.findViewById(R.id.PostDateTv);
            vPostAuthor = v.findViewById(R.id.PostAuthorTv);
            vPostTitr = v.findViewById(R.id.PostTitrTv);
            vPostPhoto = v.findViewById(R.id.PostPhoto);
            VPostLikes=v.findViewById(R.id.PostLikeTv);
            VPostViews=v.findViewById(R.id.PostViewTv);

        }

    }

    public PostDataAdapter(List<PostData> postDataList) {
        PostDataList = postDataList;
    }

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

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        holder.vPostDate.setText(PostDataList.get(position).getPostDate());
        holder.vPostTitr.setText(PostDataList.get(position).getPostTitr());
        holder.vPostContent.setText(PostDataList.get(position).getPostContent());
        holder.vPostAuthor.setText(PostDataList.get(position).getPostAuthor());
        holder.VPostViews.setText(PostDataList.get(position).getPostViews());
        holder.VPostLikes.setText(PostDataList.get(position).getPostLikes());
        new DownloadImageTask(holder.vPostPhoto).execute(PostDataList.get(position).getImgpost());
    }


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

数据类：

public class PostData {
    private String PostDate, PostContent, PostAuthor, PostTitr, imgpost, PostViews, PostLikes;

    public PostData(String postDate, String postContent, String postAuthor, String postTitr, String imgpost, String postViews, String postLikes) {
        PostDate = postDate;
        PostContent = postContent;
        PostAuthor = postAuthor;
        PostTitr = postTitr;
        this.imgpost = imgpost;
        PostViews = postViews;
        PostLikes = postLikes;
    }

    public String getPostDate() {
        return PostDate;
    }

    public void setPostDate(String postDate) {
        PostDate = postDate;
    }

    public String getPostContent() {
        return PostContent;
    }

    public void setPostContent(String postContent) {
        PostContent = postContent;
    }

    public String getPostAuthor() {
        return PostAuthor;
    }

    public void setPostAuthor(String postAuthor) {
        PostAuthor = postAuthor;
    }

    public String getPostTitr() {
        return PostTitr;
    }

    public void setPostTitr(String postTitr) {
        PostTitr = postTitr;
    }

    public String getImgpost() {
        return imgpost;
    }

    public void setImgpost(String imgpost) {
        this.imgpost = imgpost;
    }

    public String getPostViews() {
        return PostViews;
    }

    public void setPostViews(String postViews) {
        PostViews = postViews;
    }

    public String getPostLikes() {
        return PostLikes;
    }

    public void setPostLikes(String postLikes) {
        PostLikes = postLikes;
    }
}