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我試圖用RecyclerView實現無盡的無限滾動，但是我只能獲取所有記錄，甚至在嘗試滾動底部時沒有取得任何進展。RecyclerViewPagination無盡的無限滾動問題
這是News_Fragment
public class News_Fragment extends Fragment {
private List<News> newsList = new ArrayList<>();
private TextView textView;
private RecyclerView recyclerView;
private NewsAdapter newAdapter;
private ProgressBar mProgressBar;
protected Handler handler;
public News news;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_news_, container, false);
loadData();
handler = new Handler();
recyclerView = (RecyclerView) rootView.findViewById(R.id.News_recycler_view);
textView = (TextView)rootView.findViewById(R.id.empty_view);
mProgressBar = (ProgressBar) rootView.findViewById(R.id.progressBar);
//recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
recyclerView.setHasFixedSize(true);
final LinearLayoutManager mLayoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(mLayoutManager);
recyclerView.addItemDecoration(new DividerItemDecoration(getActivity(), DividerItemDecoration.VERTICAL_LIST));
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setAdapter(newAdapter);
newAdapter = new NewsAdapter(newsList,recyclerView);
if(newsList.isEmpty()){
recyclerView.setVisibility(View.GONE);
textView.setVisibility(View.VISIBLE);
}else {
recyclerView.setVisibility(View.VISIBLE);
textView.setVisibility(View.GONE);
}
newAdapter.setOnLoadMoreListener(new OnLoadMoreListener() {
@Override
public void onLoadMore() {
//add null , so the adapter will check view_type and show progress bar at bottom
newsList.add(null);
newAdapter.notifyItemInserted(newsList.size() - 1);
handler.postDelayed(new Runnable(){
@Override
public void run() {
//remove progress item
newsList.remove(newsList.size() - 1);
newAdapter.notifyItemRemoved(newsList.size());
//add items one bye one
int start = newsList.size();
int end = start + 5;
for (int i = start + 1;i <= end ; i++) {
newsList.add(new News("skip"+start,"limit"+end));
newAdapter.notifyItemInserted(newsList.size());
}
newAdapter.setLoaded();
}
},2000);
}
});
JSONObject jsonObject = new JSONObject();
try {
jsonObject.put("skip",0);
jsonObject.put("limit",50);
} catch (JSONException e) {
e.printStackTrace();
}
new NewsTask() {
@Override
protected void onPostExecute(APIResponse apiResponse) {
if (apiResponse != null && apiResponse.data != null & apiResponse.data.size() > 0) {
newsList = apiResponse.data;
//newAdapter.notifyDataSetChanged();
newAdapter = new NewsAdapter(newsList,recyclerView);
recyclerView.setAdapter(newAdapter);
}
Log.i("resp", "onPostExecute");
//Hide progressbar
mProgressBar.setVisibility(View.GONE);
}
}.execute(jsonObject);
mProgressBar.setVisibility(View.VISIBLE);
return rootView;
}
//load initial data
private void loadData(){
int start = newsList.size();
int end = start + 5;
for (int i = 1;i<=10;i++){
News news = new News("skip"+i,"limit"+i);
newsList.add(0,news);
}
}
這是NewsTask
public class NewsTask extends AsyncTask<JSONObject, Integer, APIResponse>{
ProgressDialog dialog;
OkHttpClient client = new OkHttpClient();
Gson gson = new Gson();
private ProgressBar mProgressBar;
Context context;
@Override
protected APIResponse doInBackground(JSONObject... params) {
// http://bitstobyte.in/api/news
// strat 0
// end 10
JSONObject jsonObject = params[0];
try {
String skip = jsonObject.getString("skip");
String limit = jsonObject.getString("limit");
String url = "http://bitstobyte.in/api/news?query={%22skip%22:"+skip+",%22limit%22:"+limit+"}";
Request request = new Request.Builder().url(url).build();
Response response = client.newCall(request).execute();
if(!response.isSuccessful()){
Log.v("answer","failed"+response.code());
throw new IOException("UnExpected code"+response);
}
String strResponse = response.body().string();
Log.d("News_Response",strResponse);
MainResponse mainResponse = gson.fromJson(strResponse,MainResponse.class);
// deserialze and return.
return mainResponse.msg;
}catch (IOException e) {
Log.e("searchTask",e.toString());
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
}
這是NewsAdapter
public class NewsAdapter extends RecyclerView.Adapter {
private final int VIEW_ITEM = 1;
private final int VIEW_PROG = 0;
private List<News> newsList;
private Context context;
// The minimum amount of items to have below your current scroll position
// before loading more.
private int visibleThreshold = 5;
private int lastVisibleItem, totalItemCount;
private boolean loading;
private OnLoadMoreListener onLoadMoreListener;
public NewsAdapter(List<News> newsList , RecyclerView recyclerView){
this.newsList = newsList;
this.context = context;
if(recyclerView.getLayoutManager() instanceof LinearLayoutManager) {
final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
totalItemCount = linearLayoutManager.getItemCount();
lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();
if (!loading && totalItemCount <= (lastVisibleItem + visibleThreshold)) {
// End has been reached
// Do something
if (onLoadMoreListener != null) {
onLoadMoreListener.onLoadMore();
}
loading = true;
}
}
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
// When went to the end of the list, load more posts
if (newState == RecyclerView.SCROLL_STATE_IDLE) {
if (linearLayoutManager.findLastVisibleItemPosition() >= linearLayoutManager.getItemCount() - 1) {
// Grow List
}
}
}
});
}
}
@Override
public int getItemViewType(int position){
return newsList.get(position) instanceof News ? VIEW_ITEM : VIEW_PROG;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent,int viewType) {
RecyclerView.ViewHolder vh;
if (viewType == VIEW_ITEM) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.news_list_row, parent, false);
vh = new MyViewHolder(v);
} else {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.progress_item, parent, false);
vh = new ProgressViewHolder(v);
}
return vh;
}
public class MyViewHolder extends RecyclerView.ViewHolder {
public TextView title;
public ImageView image,nextArrowimage;
public TextView desc;
private News news;
public MyViewHolder(View view) {
super(view);
title = (TextView) view.findViewById(R.id.News_title);
image = (ImageView) view.findViewById(R.id.News_imageView);
nextArrowimage = (ImageView)view.findViewById(R.id.news_NextArrow);
desc = (TextView) view.findViewById(R.id.News_desc);
view.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String title = news.getTitle();
String desc = news.getDesc();
String image = "http://bitstobyte.in/upload/"+news.getImage();
Intent intent = new Intent(context, News_Activity.class);
intent.putExtra("title", title);
intent.putExtra("desc",desc);
intent.putExtra("imageUrl", image);
context.startActivity(intent);
Toast.makeText(v.getContext(), "OnClick :" + news.getTitle() + " \n "+news.getImage(),Toast.LENGTH_SHORT).show();
}
});
}
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder,int position){
if (holder instanceof MyViewHolder) {
final News single_news= (News) newsList.get(position);
((MyViewHolder) holder).title.setText(single_news.getTitle());
((MyViewHolder) holder).desc.setText(single_news.getDesc());
((MyViewHolder) holder).nextArrowimage.setImageResource(R.drawable.nextblackbutton);
context = ((MyViewHolder) holder).image.getContext();
Picasso.with(context).load("http://bitstobyte.in/upload/"+single_news.getImage()).placeholder(R.drawable.ic_favorite_white_24dp).error(R.drawable.ic_map_24dp).resize(100,100).into(((MyViewHolder) holder).image);
((MyViewHolder) holder).news= single_news;
} else {
((ProgressViewHolder) holder).progressBar.setIndeterminate(true);
}
}
public void setLoaded() {
loading = false;
}
@Override
public int getItemCount() {
return newsList.size();
}
public void setOnLoadMoreListener(OnLoadMoreListener onLoadMoreListener) {
this.onLoadMoreListener = onLoadMoreListener;
}
public static class ProgressViewHolder extends RecyclerView.ViewHolder {
public ProgressBar progressBar;
public ProgressViewHolder(View v) {
super(v);
progressBar = (ProgressBar) v.findViewById(R.id.progressBar1);
}
}
}
這是JSON數據
{
"status": "ok",
"msg": {
"current": 58,
"total": 58,
"data": [{
"title": "dfdsfsdf",
"machineId": "1bc99f0a-f138-428b-9b54-5531e4c8fc3f",
"image": "55a88fbfbc54f41570840e11.jpg",
"partnerId": "558be1a2e1d33656b06ddbd7",
"_id": "55a88fbfbc54f41570840e11",
"desc": "fsfsdfdsfdsf"
}, {
"title": "one more test",
"machineId": "1bc99f0a-f138-428b-9b54-5531e4c8fc3f",
"image": "55a8901abc54f41570840e12.jpg",
"partnerId": "558be1a2e1d33656b06ddbd7",
"_id": "55a8901abc54f41570840e12",
"desc": "good.."
},
我改變了代碼....但不工作 –
我已經編輯onBindViewHolder getItemType @kranthikumar –
我得到這個錯誤：java.lang.NullPointerException：試圖調用虛擬方法'java.lang.String com.example.shilpa.churchcms.models.News.getTitle（）'對空引用 –