How to load more data in recycler view from server

问题:

I have a recycler view in which I load some data from the server when user scroll to bottom I want to show a progress bar and send another request to the server for more data. I have tried below code but it not able to load more data from the server. please help

   private RecyclerView mRecyclerView;
    private List<User> mUsers = new ArrayList<>();
    private UserAdapter mUserAdapter;
    private static String sz_RecordCount;
    private static String sz_LastCount;
    private final int m_n_DefaultRecordCount = m_kDEFAULT_RECORD_COUNT;
    private static final int m_kDEFAULT_RECORD_COUNT = 5;
    private ArrayList<CDealAppDatastorage> s_oDataset;
    private String TAG = MainActivity.class.getSimpleName();
    private CDealAppDatastorage item;
    private static int arrayCount;
    private Context context;
    private PreferenceHelper m_oPreferenceHelper;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        context = MainActivity.this;
        m_oPreferenceHelper = new PreferenceHelper(context);

        sz_RecordCount = String.valueOf(m_n_DefaultRecordCount);// increment of record count
        int intialLastCount = 0;
        sz_LastCount = String.valueOf(intialLastCount);// increment of last count...

        s_oDataset = new ArrayList<>();// making object of Arraylist
        //initial request for data
        initalDealListing();


        mRecyclerView = (RecyclerView) findViewById(R.id.recycleView);

        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        mUserAdapter = new UserAdapter();


        mUserAdapter.setOnLoadMoreListener(new OnLoadMoreListener() {
            @Override
            public void onLoadMore() {
                Log.e("haint", "Load More");
                mUsers.add(null);
                mUserAdapter.notifyItemInserted(mUsers.size() - 1);

                //Load more data for reyclerview
                new Handler().postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        Log.e("haint", "Load More 2");


                        //Remove loading item
                        mUsers.remove(mUsers.size() - 1);
                        mUserAdapter.notifyItemRemoved(mUsers.size());
                        //sending request to server for more data
                        moreDealsRequest();

                        mUserAdapter.notifyDataSetChanged();
                        mUserAdapter.setLoaded();
                    }
                }, 5000);
            }
        });
    }

    private void initalDealListing() {
        String m = "9565656565";
        String p = "D55A8077E0208A5C5B25176608EF84BD";
        // 3. build jsonObject
        try {
            final JSONObject jsonObject = new JSONObject();// making object of Jsons.
            jsonObject.put("agentCode", m.trim());// put mobile number
            jsonObject.put("pin", p.trim());// put password
            jsonObject.put("recordcount", sz_RecordCount.trim());// put record count
            jsonObject.put("lastcountvalue", sz_LastCount.trim());// put last count
            Log.e("CAppList:", sz_RecordCount);
            Log.e("Capplist:", sz_LastCount);
            Log.d(TAG, "Server Request:-" + jsonObject.toString());
            final String m_DealListingURL = APIStorage.IREWARDS_URL + APIStorage.DEALLISTING_URL;
            JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.POST, m_DealListingURL, jsonObject, new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response) {
                    Log.d(TAG, "Server Response:-" + response);

                    try {
                        int nResultCodeFromServer = Integer.parseInt(response.getString(ServerResponseStorage.s_szRESULT_CODE));
                        if (nResultCodeFromServer == ConstantInt.m_kTRANSACTION_SUCCESS) {

                            JSONArray posts = response.optJSONArray(ServerResponseStorage.s_szDEAL_ARRAY);// get Deal list in array from response
                            s_oDataset.clear();
                            for (int i = 0; i < posts.length(); i++) {// loop for counting deals from server
                                try {
                                    JSONObject post = posts.getJSONObject(i);// counting deal based on index
                                    item = new CDealAppDatastorage();// creating object of DealAppdata storage
                                    item.setM_szHeaderText(post.getString(ServerResponseStorage.s_szDEAL_NAME));// get deal name from response
                                    item.setM_szsubHeaderText(post.getString(ServerResponseStorage.s_szDEAL_CODE));// get dealcode from response
                                    s_oDataset.add(item);// add all items in ArrayList
                                } catch (Exception e) {
                                    e.printStackTrace();
                                }
                            }
                            arrayCount = posts.length();
                            Log.d(TAG, "ArrayCount::" + arrayCount);
                            /*here we are storing no. of deals coming from server*/
                            // write
                            m_oPreferenceHelper.saveIntegerValue("LastCountLength", arrayCount);
                            if (!s_oDataset.isEmpty()) {// condition if data in arraylist is not empty
                                mRecyclerView.setAdapter(mUserAdapter);
                            }


                        }

                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Log.d(TAG, "Server error:-" + error);
                }
            });
            RequestQueue requestQueue = Volley.newRequestQueue(context);
            jsonObjectRequest.setRetryPolicy(new DefaultRetryPolicy(ConstantInt.INITIAL_TIMEOUT_MS, DefaultRetryPolicy.DEFAULT_MAX_RETRIES, DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
            requestQueue.add(jsonObjectRequest);
        } catch (JSONException e) {
            e.printStackTrace();
        }

    }

    /*This method send request to server for more deals*/
    private void moreDealsRequest() {
        try {
            // 3. build jsonObject
            final JSONObject jsonObject = new JSONObject();// making object of Jsons.
            jsonObject.put(ServerRequestKeyStorage.s_szAGENT_CODE, "9565656565");// put mobile number
            jsonObject.put(ServerRequestKeyStorage.s_szPASSWORD, "D55A8077E0208A5C5B25176608EF84BD");// put password
            jsonObject.put(ServerRequestKeyStorage.s_szRECORD_COUNT, sz_RecordCount.trim());// put record count
            jsonObject.put(ServerRequestKeyStorage.s_szLAST_COUNT, sz_LastCount.trim());// put last count
            Log.e("CAppList:", sz_RecordCount);
            Log.e("Capplist:", sz_LastCount);
            // 4. convert JSONObject to JSON to String

            Log.e(TAG, "Server Request:-" + jsonObject.toString());
            RequestQueue requestQueue = Volley.newRequestQueue(context);
            final String imgPath = APIStorage.IREWARDS_URL + APIStorage.DEAL_IMAGE_PATH;
            final String m_DealListingURL = APIStorage.IREWARDS_URL + APIStorage.DEALLISTING_URL;
            JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.POST, m_DealListingURL, jsonObject, new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response) {
                    Log.e(TAG, "Server Response:-" + response);
                    try {
                        int nResultCodeFromServer = Integer.parseInt(response.getString(ServerResponseStorage.s_szRESULT_CODE));

                        if (nResultCodeFromServer == ConstantInt.m_kTRANSACTION_SUCCESS) {
                            // Select the last row so it will scroll into view...
                            JSONArray posts = response.optJSONArray(ServerResponseStorage.s_szDEAL_ARRAY);// GETTING DEAL LIST
                            for (int i = 0; i < posts.length(); i++) {
                                try {
                                    JSONObject post = posts.getJSONObject(i);// GETTING DEAL AT POSITION AT I
                                    item = new CDealAppDatastorage();// object create of DealAppdatastorage
                                    item.setM_szHeaderText(post.getString(ServerResponseStorage.s_szDEAL_NAME));//getting deal name
                                    item.setM_szsubHeaderText(post.getString(ServerResponseStorage.s_szDEAL_CODE));// getting deal code
                                    s_oDataset.add(item);
                                } catch (Exception e) {
                                    e.printStackTrace();
                                }
                            }

                        }


                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Log.d(TAG, "Server Error::" + error);
                }
            });
            jsonObjectRequest.setRetryPolicy(new DefaultRetryPolicy(ConstantInt.INITIAL_TIMEOUT_MS, DefaultRetryPolicy.DEFAULT_MAX_RETRIES, DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
            requestQueue.add(jsonObjectRequest);
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    static class UserViewHolder extends RecyclerView.ViewHolder {
        public TextView tvName;
        public TextView tvEmailId;

        public UserViewHolder(View itemView) {
            super(itemView);
            tvName = (TextView) itemView.findViewById(R.id.tvName);

            tvEmailId = (TextView) itemView.findViewById(R.id.tvEmailId);
        }
    }

    static class LoadingViewHolder extends RecyclerView.ViewHolder {
        public ProgressBar progressBar;

        public LoadingViewHolder(View itemView) {
            super(itemView);
            progressBar = (ProgressBar) itemView.findViewById(R.id.progressBar1);
        }
    }

    class UserAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

        private final int VIEW_TYPE_ITEM = 0;
        private final int VIEW_TYPE_LOADING = 1;

        private OnLoadMoreListener mOnLoadMoreListener;

        private boolean isLoading;
        private int visibleThreshold = 5;
        private int lastVisibleItem, totalItemCount;

        public UserAdapter() {
            final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) mRecyclerView.getLayoutManager();
            mRecyclerView.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 (!isLoading && totalItemCount <= (lastVisibleItem + visibleThreshold)) {
                        if (mOnLoadMoreListener != null) {
                            mOnLoadMoreListener.onLoadMore();
                        }
                        isLoading = true;
                    }
                }
            });
        }

        public void setOnLoadMoreListener(OnLoadMoreListener mOnLoadMoreListener) {
            this.mOnLoadMoreListener = mOnLoadMoreListener;
        }

        @Override
        public int getItemViewType(int position) {
            return s_oDataset.get(position) == null ? VIEW_TYPE_LOADING : VIEW_TYPE_ITEM;
        }

        @Override
        public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            if (viewType == VIEW_TYPE_ITEM) {
                View view = LayoutInflater.from(MainActivity.this).inflate(R.layout.layout_user_item, parent, false);
                return new UserViewHolder(view);
            } else if (viewType == VIEW_TYPE_LOADING) {
                View view = LayoutInflater.from(MainActivity.this).inflate(R.layout.layout_loading_item, parent, false);
                return new LoadingViewHolder(view);
            }
            return null;
        }

        @Override
        public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
            if (holder instanceof UserViewHolder) {
                CDealAppDatastorage user = s_oDataset.get(position);
                UserViewHolder userViewHolder = (UserViewHolder) holder;
                userViewHolder.tvName.setText(user.getM_szHeaderText());
                userViewHolder.tvEmailId.setText(user.getM_szsubHeaderText());
            } else if (holder instanceof LoadingViewHolder) {
                LoadingViewHolder loadingViewHolder = (LoadingViewHolder) holder;
                loadingViewHolder.progressBar.setIndeterminate(true);
            }
        }

        @Override
        public int getItemCount() {
            return s_oDataset == null ? 0 : s_oDataset.size();
        }

        public void setLoaded() {
            isLoading = false;
        }
    }
}

回答1:

Use Below Code:

First Declare these global variables:

int visibleItemCount, totalItemCount = 1;
int firstVisiblesItems = 0;
int totalPages = 1; // get your total pages from web service first response
int current_page = 0;

boolean canLoadMoreData = true; // make this variable false while your web service call is going on.

LinearLayoutManager linearLayoutManager;

Assign Layout manager to your Recyclerview:

linearLayoutManager = new LinearLayoutManager(mActivity);
mRecyclerView.setLayoutManager(linearLayoutManager);

Scroll Listener of your recyclerview:

mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
            if (dy > 0) //check for scroll down
            {
                visibleItemCount = linearLayoutManager.getChildCount();
                totalItemCount = linearLayoutManager.getItemCount();
                firstVisiblesItems = linearLayoutManager.findFirstVisibleItemPosition();

                    if (canLoadMoreData) {
                        if ((visibleItemCount + firstVisiblesItems) >= totalItemCount) {
                            if (current_page < totalPages) {
                                canLoadMoreData  = false;
                                /**
                                 * .
                                 * .
                                 * .
                                 * .call your webservice with page index
                                 * .
                                 * .
                                 *
                                 */
                                //After completion of web service make 'canLoadMoreData = true'
                            }
                        }
                    }

            }
        }
    });

回答2:

Too late but i'm also refer same way check with my code it work for me

Here is API call using retrofit and get listnotifications then in this method i create one more method for loadmore getMoreNotificationListApiCall()

public void getNotification()
 {
    if (listnotifications.size() > 0) {
                                        notificationListAdapter = new NotificationListAdapter(NotificationListActivity.this, listnotifications, notificationListRecyclerview);
                                        notificationListRecyclerview.setAdapter(notificationListAdapter);

                                        notificationListAdapter.setOnLoadMoreListener(new OnLoadMoreListener() {
                                            @Override
                                            public void onLoadMore() {
                                                Log.e("ad", "Load More");

                                                listnotifications.add(null);

                                                Handler handler = new Handler();
                                                final Runnable r = new Runnable() {
                                                    public void run() {
                                                        if (listnotifications.size()>0) {
                                                            notificationListAdapter.notifyItemInserted(listnotifications.size() - 1);
                                                        }
                                                    }
                                                };
                                                handler.post(r);

                                                try {

                                                    if (CommonUtils.isConnectingToInternet(NotificationListActivity.this)) {
                                                        // Internet Connection is Present
                                                        getMoreNotificationListApiCall();

                                                    } else {
                                                        //Remove loading item
                                                        if (listnotifications.size()>0) {
                                                            listnotifications.remove(listnotifications.size() - 1);
                                                        }

                                                        notificationListAdapter.notifyItemRemoved(listnotifications.size());
                                                        CommonUtils.commonToast(NotificationListActivity.this, getResources().getString(R.string.no_internet_exist));
                                                    }

                                                } catch (Exception e) {
                                                    // TODO Auto-generated catch block
                                                    e.printStackTrace();
                                                }

                                            }
                                        });


                                    }

    }

getMoreNotificationListApiCall() method code in this method i increment startlimit means page index and remove null (i'm using retorfit for api call)

private void getMoreNotificationListApiCall() {
    try {
        if (CommonUtils.isConnectingToInternet(NotificationListActivity.this)) {

            StartLimit = StartLimit + 10;

            Call<NotificationBase> call = ApiHandler.getApiService().getNotificationListApi(notificationListJsonMap());

            call.enqueue(new Callback<NotificationBase>() {
                @Override
                public void onResponse(Call<NotificationBase> registerCall, Response<NotificationBase> response) {
                    Log.e(TAG, " Full json gson => " + "Hi i am here");
                    try {
                        Log.e(TAG, " Full json gson => " + new Gson().toJson(response));
                        JSONObject jsonObj = new JSONObject(new Gson().toJson(response).toString());
                        Log.e(TAG, " responce => " + jsonObj.getJSONObject("body").toString());

                        if (response.isSuccessful()) {
                            int success = response.body().getSuccess();
                            if (success == 1) {

                                List<NotificationBean> moreNotication = response.body().getNotificatons();

                                //Remove loading item
                                if (listnotifications.size() > 0) {
                                    listnotifications.remove(listnotifications.size() - 1);
                                }

                                notificationListAdapter.notifyItemRemoved(listnotifications.size());

                                for (int i = 0; i < moreNotication.size(); i++) {
                                    listnotifications.add(moreNotication.get(i));
                                }

                                notificationListAdapter.notifyDataSetChanged();
                                notificationListAdapter.setLoaded();


                            } else if (success == 0) {
                                if (listnotifications.size() > 0) {
                                    listnotifications.remove(listnotifications.size() - 1);
                                }
                                notificationListAdapter.notifyItemRemoved(listnotifications.size());

                            } else {
                                if (listnotifications.size() > 0) {
                                    listnotifications.remove(listnotifications.size() - 1);
                                }
                                notificationListAdapter.notifyItemRemoved(listnotifications.size());

                            }
                        } else {
                            if (listnotifications.size() > 0) {
                                listnotifications.remove(listnotifications.size() - 1);
                            }
                            notificationListAdapter.notifyItemRemoved(listnotifications.size());
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                        try {
                            Log.e(TAG, "error=" + e.toString());
                            if (listnotifications.size() > 0) {
                                listnotifications.remove(listnotifications.size() - 1);
                            }
                            notificationListAdapter.notifyItemRemoved(listnotifications.size());
                        } catch (Resources.NotFoundException e1) {
                            e1.printStackTrace();
                        }

                    }
                }

                @Override
                public void onFailure(Call<NotificationBase> call, Throwable t) {
                    try {
                        Log.e(TAG, "error" + t.toString());
                        if (listnotifications.size() > 0) {
                            listnotifications.remove(listnotifications.size() - 1);
                        }
                        notificationListAdapter.notifyItemRemoved(listnotifications.size());
                    } catch (Resources.NotFoundException e) {
                        e.printStackTrace();
                    }
                }
            });
        } else {
            CommonUtils.commonToast(NotificationListActivity.this, getResources().getString(R.string.no_internet_exist));

        }
    } catch (Resources.NotFoundException e) {
        e.printStackTrace();
    }
}

Here is my Adapter class in which i implement OnLoadMoreListener

public class NotificationListAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {


public static List<NotificationBean> mList;
private final int VIEW_TYPE_ITEM = 0;
private final int VIEW_TYPE_LOADING = 1;
FragmentActivity mFragmentActivity;

private OnLoadMoreListener mOnLoadMoreListener;
private boolean isLoading;
private int visibleThreshold = 5;
private int lastVisibleItem, totalItemCount;

public NotificationListAdapter(FragmentActivity fragmentActivity, List<NotificationBean> data, RecyclerView mRecyclerView) {
    this.mList = data;
    this.mFragmentActivity = fragmentActivity;

    final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) mRecyclerView.getLayoutManager();

    mRecyclerView.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 (!isLoading && totalItemCount <= (lastVisibleItem + visibleThreshold)) {
                if (mOnLoadMoreListener != null) {
                    mOnLoadMoreListener.onLoadMore();
                }
                isLoading = true;
            }
        }
    });
}

public void setOnLoadMoreListener(OnLoadMoreListener mOnLoadMoreListener) {
    this.mOnLoadMoreListener = mOnLoadMoreListener;
}


@Override
public int getItemViewType(int position) {
    return mList.get(position) == null ? VIEW_TYPE_LOADING : VIEW_TYPE_ITEM;
}

public void delete(int position) { //removes the row
    Log.e("Position : ", "" + position);
    mList.remove(position);
    notifyItemRemoved(position);
    notifyItemRangeChanged(position, mList.size());

}




// Return the size arraylist
@Override
public int getItemCount() {
    return mList == null ? 0 : mList.size();
}

public void setLoaded() {
    isLoading = false;
}

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    if (viewType == VIEW_TYPE_ITEM) {
        // create a new view
        View itemLayoutView = LayoutInflater.from(parent.getContext()).inflate(
                R.layout.item_notification_list, parent, false);

        return new ViewHolder(itemLayoutView);
    } else if (viewType == VIEW_TYPE_LOADING) {

        View itemLayoutView = LayoutInflater.from(parent.getContext()).inflate(
                R.layout.loading_layout, parent, false);

        return new LoadingViewHolder(itemLayoutView);
    }
    return null;
}

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, final int position) {
    if (holder instanceof ViewHolder) {

        try {

            final ViewHolder viewHolder = (ViewHolder) holder;
            viewHolder.singleBean = mList.get(position);
            viewHolder.pos = position;
            final NotificationBean list = mList.get(position);


            String notificationTitle = list.getMessage();
            String notificationTimeDate = list.getCreatedDatetime();

            String notificationIsRead = list.getIsRead();

        } catch (Exception e) {
            e.printStackTrace();
        }
    } else if (holder instanceof LoadingViewHolder) {
        LoadingViewHolder loadingViewHolder = (LoadingViewHolder) holder;
        loadingViewHolder.progressBar.setIndeterminate(true);
    }


}

static class LoadingViewHolder extends RecyclerView.ViewHolder {
    public ProgressBar progressBar;

    public LoadingViewHolder(View itemView) {
        super(itemView);
        progressBar = (ProgressBar) itemView.findViewById(R.id.progressBar1);
    }
}

public class ViewHolder extends RecyclerView.ViewHolder {


    public NotificationBean singleBean;
    int pos;

    TextView txt_notification_time_date;
    CustomTextview checkbox_notification;
    RelativeLayout rl_row_background;

    public ViewHolder(final View v) {
        super(v);

        checkbox_notification = (CustomTextview) v.findViewById(R.id.checkbox_notification);
        //checkbox_notification.setButtonDrawable(android.R.color.transparent);//custom_checkbox

        // txt_notification_title= (TextView) v.findViewById(R.id.txt_notification_title);
        txt_notification_time_date = (TextView) v.findViewById(R.id.txt_notification_time_date);
        rl_row_background = (RelativeLayout) v.findViewById(R.id.rl_row_background);


    }
}
public void refreshAdapter() {
    notifyDataSetChanged();
}



 }

here is xml file loading_layout.xml

 <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    android:gravity="center_horizontal"
    android:orientation="vertical">
    <ProgressBar
        android:id="@+id/progressBar1"
        style="@style/Widget.AppCompat.ProgressBar.Horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" android:layout_marginBottom="5dp"
        android:layout_marginTop="5dp"
        android:indeterminate="true" />

</LinearLayout>

回答3:

Fetching the data from server is a Async Task. So you need to enclose the updation code in a runOnUiThread runnable. to change UI.

runOnUiThread(new Runnable() {
   @Override
   public void run() {
      mUsers.remove(mUsers.size() - 1);
      mUserAdapter.notifyItemRemoved(mUsers.size());
      //sending request to server for more data
      moreDealsRequest();
      mUserAdapter.notifyDataSetChanged();
      mUserAdapter.setLoaded();
}});