Android RecyclerView + CursorLoader + ContentProvider + "Load More"

Question

I have created one Activity in that I am implementing CursorLoader for load data from Database.

I have done that thing for all records of that Table but I want to load 30-30 records like Load More Functionality

I have tried to create query and its loading first 30 records but I cant able to understand how can I request for new records.

My Activity Code is Like:

public class ProductListActivity extends AppCompatActivity
        implements LoaderManager.LoaderCallbacks<Cursor> {

    /**
     * Records in list
     */
    int offset = 0;

    /**
     * For Current Activity *
     */
    Context mContext;

    /**
     * Activity Binding
     */
    ActivityProductListBinding activityProductListBinding;

    /**
     * Product Adapter
     */
    ProductListAdapter productListAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        /**
         * DataBinding with XML
         */
        activityProductListBinding = DataBindingUtil.setContentView(this, R.layout.activity_product_list);

        /**
         * Getting Context
         */
        mContext = getApplicationContext();

        /***
         * TOOLBAR Settings...
         */
        setSupportActionBar(activityProductListBinding.toolbar);
        activityProductListBinding.toolbarTitleTextview.setText(R.string.string_title_products);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setDisplayShowTitleEnabled(false);

        final ActionBar ab = getSupportActionBar();
        if (ab != null)
            ab.setDisplayHomeAsUpEnabled(true);

        /**
         * RecyclerView Setup
         */
        GridLayoutManager manager = new GridLayoutManager(this, 2);
        activityProductListBinding.productListRecyclerView.setLayoutManager(manager);

        /**
         * First Time init Loader
         */
        getSupportLoaderManager().initLoader(1, null, this);
    }

    @Override
    public Loader<Cursor> onCreateLoader(int id, Bundle args) {
        final Uri CONTENT_URI = KOOPSContentProvider.CONTENT_URI_PRODUCT.buildUpon()
                .appendQueryParameter(KOOPSContentProvider.QUERY_PARAMETER_OFFSET,
                        String.valueOf(offset))
                .build();
        return new CursorLoader(this, CONTENT_URI ,null, null, null, null);
    }

    @Override
    public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
        //When the loader has loaded some data (either initially, or the
        //datasource has changed and a new cursor is being provided),
        //Then we'll swap out the cursor in our recyclerview's adapter
        // and we'll create the adapter if necessary
        Log.d(LogUtils.TAG, "Cursor : " + data.getCount());
        if (productListAdapter == null) {
            productListAdapter = new ProductListAdapter(this, data);
            activityProductListBinding.productListRecyclerView.setAdapter(productListAdapter);
        }
    }

    @Override
    public void onLoaderReset(Loader<Cursor> loader) {
        //If the loader is reset, we need to clear out the
        //current cursor from the adapter.
        productListAdapter.reQuery(null);
    }
}

UPDATE:

I have added EndlessRecyclerViewScrollListener

activityProductListBinding.productListRecyclerView.addOnScrollListener(new EndlessRecyclerViewScrollListener(manager) {
            @Override
            public void onLoadMore(int page, int totalItemsCount) {
                // Triggered only when new data needs to be appended to the list
                // Add whatever code is needed to append new items to the bottom of the list
                offset = limit * page;
                /**
                 * Adding Bundle in Loader and then Call
                 */
                getSupportLoaderManager().initLoader(LOADER_ID, productQueryData, ProductListActivity.this);
            }
        });

I have tried to MergeCursor in adapter but getting error:

FATAL EXCEPTION: main

Process: com.kevalam.koopsv3, PID: 25021

java.lang.IllegalStateException: Observer android.database.MergeCursor$1@570f82d is already registered.
    at android.database.Observable.registerObserver(Observable.java:49)
    at android.database.AbstractCursor.registerDataSetObserver(AbstractCursor.java:358)
    at android.database.CursorWrapper.registerDataSetObserver(CursorWrapper.java:222)
    at android.database.MergeCursor.<init>(MergeCursor.java:50)
    at com.kevalam.koops.adapter.ProductListAdapter.mergeCursor(ProductListAdapter.java:71)
    at com.kevalam.koops.ui.ProductListActivity.onLoadFinished(ProductListActivity.java:161)
    at com.kevalam.koops.ui.ProductListActivity.onLoadFinished(ProductListActivity.java:38)

Edited (ADAPTER Code):

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

    // Because RecyclerView.Adapter in its current form doesn't natively 
    // support cursors, we wrap a CursorAdapter that will do all the job
    // for us.
    CursorAdapter mCursorAdapter;

    Activity mContext;
    Random rnd;

    public ProductListAdapter(AppCompatActivity context, Cursor c) {

        mContext = context;
        rnd = new Random();

        mCursorAdapter = new CursorAdapter(mContext, c, 0) {

            @Override
            public View newView(Context context, Cursor cursor, ViewGroup parent) {
                // Inflate the view here
                LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                return inflater.inflate(R.layout.row_product_layout_grid, parent, false);
            }

            @Override
            public void bindView(View view, Context context, Cursor cursor) {
                String productName = cursor.getString(cursor.getColumnIndex(PRODUCT_NAME));

                // Binding operations
                ((TextView) view.findViewById(R.id.sub_product_name_text_view)).setText(productName);

                int color = Color.argb(200, rnd.nextInt(256), rnd.nextInt(256), rnd.nextInt(256));

                String url = "http://dummyimage.com/300/" + color + "/ffffff&text=" + (cursor.getPosition() + 1);

                Picasso
                        .with(context)
                        .load(url)
                        .placeholder(R.mipmap.ic_launcher) // can also be a drawable
                        .into((ImageView) view.findViewById(R.id.sub_product_image_view));
            }
        };
    }

    public void mergeCursor(Cursor c) {
        if (mCursorAdapter != null) {
            Cursor[] cursorArray = {mCursorAdapter.getCursor(), c};
            MergeCursor mergeCursor = new MergeCursor(cursorArray);
            reQuery(mergeCursor);
        }
    }

    public void reQuery(Cursor c) {
        if (mCursorAdapter != null) {
            mCursorAdapter.changeCursor(c);
            mCursorAdapter.notifyDataSetChanged();
            notifyDataSetChanged();
        }
    }

    @Override
    public int getItemCount() {
        return mCursorAdapter.getCount();
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        // Passing the binding operation to cursor loader
        mCursorAdapter.getCursor().moveToPosition(position); //EDITED: added this line as suggested in the comments below, thanks :)
        mCursorAdapter.bindView(holder.view, mContext, mCursorAdapter.getCursor());
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        // Passing the inflater job to the cursor-adapter
        View v = mCursorAdapter.newView(mContext, mCursorAdapter.getCursor(), parent);
        return new ViewHolder(v);
    }

    public static class ViewHolder extends RecyclerView.ViewHolder {
        View view;

        public ViewHolder(View itemView) {
            super(itemView);
            view = itemView.findViewById(R.id.product_row_card_view);
        }
    }
}

Anybody can help please, Thanks in advance.

You have to use pagintaion concept.Send pageno and pag size and get another data — Damini Mehra, Oct 03 '16 at 06:02
But How can I use that on previous Cursor, Is it possible to update cursor and adapter with that Loader? — Pratik Butani, Oct 03 '16 at 06:20
Plz check this so ref: http://stackoverflow.com/questions/17340850/pagination-with-sqlite-using-limit — Damini Mehra, Oct 03 '16 at 06:28
all you need is [this](https://gist.github.com/Shywim/127f207e7248fe48400b) adapter, there is absolutly no need to "paginate" the `SQLiteCursor` as it "paginates" by itself extending `AbstractWindowedCursor` — pskink, Oct 03 '16 at 06:46
@DaminiMehra Thanks for your help but I want to do that with *CursorLoader* — Pratik Butani, Oct 03 '16 at 06:53
@pskink I didn't get you, If I have 100000 records then How it will manage? — Pratik Butani, Oct 03 '16 at 06:55
Its simple: even if you have 1,000,000 or 10,000,000 rows at first a small window is used to store first lets say 1000 rows and then as you scroll down the window can be filled with next 1000 rows, all it happens under the hood so you are even not aware of this — pskink, Oct 03 '16 at 08:05
But Query for 100000 records will take more time then 100 records @pskink — Pratik Butani, Oct 03 '16 at 08:55
see [this](http://pastebin.com/6EZQSk9p) code and results: it is from my emulator, you will notice it is not linear, if 300ms is too much then call `initLoader` twice: first to read some small number of rows (100 for example) which will load in 10ms or so (and you see them right now) and the second with no row limit — pskink, Oct 03 '16 at 09:28
just call it twice: one after another, or if you like when the first loader finishes (`onLoadFinished` is called) — pskink, Oct 07 '16 at 10:55
I've updated my question with EndlessScroll but getting errors as described.@pskink — Pratik Butani, Oct 07 '16 at 10:56
if you want `onLoadMore` so wait for someone else, i already said it is pointless to use any "pagination" — pskink, Oct 07 '16 at 10:59
As you said: If i call two times initLoader then new cursor will be replaced by old. How it will be possible. I am confused. @pskink — Pratik Butani, Oct 07 '16 at 11:05
i said: `"first to read some small number of rows (100 for example) which will load in 10ms or so (and you see them right now) and the second with no row limit"` and yes, the second cursor will replace the first since the first will contain rows 0..99 and the second rows 0..max-1 — pskink, Oct 07 '16 at 11:06
1. does it have to use databinding? 2. Does Your recyclerview must store data in arraylist or cursoradapter or modified recyclerview with cursoradapter? — deadfish, Oct 10 '16 at 13:41
@deadfish Yes I have created CustomCursorAdapter using *RecylcerViewAdapter + CursorAdapter* and also I have used DataBinding excepting adapter row file. — Pratik Butani, Oct 11 '16 at 04:53

deadfish · Accepted Answer · 2017-10-01T21:56:21.103

Update 01.10.2017 Google announced new library for paging, more info here https://developer.android.com/topic/libraries/architecture/paging.html

Here is working sample with pagination based on cursoradapter+recyclerview+provider.

I give you step by step with code + bonus with gif preview.

But IMHO pagination on cursor adapter has nonsense because db is handling all heavy stuff with load more data :)

Step 1. create database:

public class CustomSqliteOpenHelper extends SQLiteOpenHelper {

    private static final String TAG = "CustomSqliteOpenHelper";

    public CustomSqliteOpenHelper(Context context) {
        super(context, "db.db", null, 1);
    }

    @Override
    public void onOpen(SQLiteDatabase db) {
        super.onOpen(db);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(TableItems.CREATE_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL(TableItems.DROP_TABLE);
        onCreate(db);
    } 
}

Step 2. create table

public class TableItems {
    public static final String NAME = TableItems.class.getSimpleName().toLowerCase();
    public static final String _ID = "_id";
    public static final String TEXT = "text";

    public static final String CREATE_TABLE =
            "CREATE TABLE " + NAME +
                    " ( " +
                    _ID + " integer primary key autoincrement, " +
                    TEXT + " text " +
                    " ); ";

    public static final String DROP_TABLE = "DROP TABLE IF EXISTS " + NAME;
    public static String[] Columns = new String[]{_ID, TEXT};
}

Step 3. create provider

import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteQueryBuilder;
import android.net.Uri;
import android.support.annotation.NonNull;
import android.util.Log;

import com.example.pagingproject.BuildConfig;

public class RequestProvider extends ContentProvider {
    private static final String TAG = "RequestProvider";

    private SQLiteOpenHelper mSqliteOpenHelper;
    private static final UriMatcher sUriMatcher;

    public static final String AUTHORITY = BuildConfig.APPLICATION_ID + ".db";

    private static final int
            TABLE_ITEMS = 0;

    static {
        sUriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        sUriMatcher.addURI(AUTHORITY, TableItems.NAME + "/offset/" + "#", TABLE_ITEMS);
    }

    public static Uri urlForItems(int limit) {
        return Uri.parse("content://" + AUTHORITY + "/" + TableItems.NAME + "/offset/" + limit);
    }

    @Override
    public boolean onCreate() {
        mSqliteOpenHelper = new CustomSqliteOpenHelper(getContext());
        return true;
    }

    @Override
    synchronized public Cursor query(@NonNull Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {

        SQLiteDatabase db = mSqliteOpenHelper.getReadableDatabase();
        SQLiteQueryBuilder sqb = new SQLiteQueryBuilder();
        Cursor c = null;
        String offset;

        switch (sUriMatcher.match(uri)) {
            case TABLE_ITEMS: {
                sqb.setTables(TableItems.NAME);
                offset = uri.getLastPathSegment();
                break;
            }

            default:
                throw new IllegalArgumentException("uri not recognized!");
        }

        int intOffset = Integer.parseInt(offset);

        String limitArg = intOffset + ", " + 30;
        Log.d(TAG, "query: " + limitArg);
        c = sqb.query(db, projection, selection, selectionArgs, null, null, sortOrder, limitArg);

        c.setNotificationUri(getContext().getContentResolver(), uri);

        return c;
    }

    @Override
    public String getType(@NonNull Uri uri) {
        return BuildConfig.APPLICATION_ID + ".item";
    }

    @Override
    public Uri insert(@NonNull Uri uri, ContentValues values) {
        String table = "";
        switch (sUriMatcher.match(uri)) {
            case TABLE_ITEMS: {
                table = TableItems.NAME;
                break;
            }
        }

        long result = mSqliteOpenHelper.getWritableDatabase().insertWithOnConflict(table, null, values, SQLiteDatabase.CONFLICT_IGNORE);

        if (result == -1) {
            throw new SQLException("insert with conflict!");
        }

        Uri retUri = ContentUris.withAppendedId(uri, result);
        return retUri;
    }

    @Override
    public int delete(@NonNull Uri uri, String selection, String[] selectionArgs) {
        return -1;
    }

    @Override
    public int update(@NonNull Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        return -1;
    }
}

Step 4. create an abstract cursor adapters, I took sample from StackOverflow custom-cursor-recyclerView-adapter

import android.content.Context;
import android.database.Cursor;
import android.database.DataSetObserver;
import android.support.v7.widget.RecyclerView;
import android.view.ViewGroup;

/**
 * Created by skyfishjy on 10/31/14.
 */

public abstract class CursorRecyclerViewAdapter<VH extends RecyclerView.ViewHolder> extends RecyclerView.Adapter<VH> {

    protected Context mContext;

    private Cursor mCursor;

    private boolean mDataValid;

    private int mRowIdColumn;

    private DataSetObserver mDataSetObserver;

    public CursorRecyclerViewAdapter(Context context, Cursor cursor) {
        mContext = context;
        mCursor = cursor;
        mDataValid = cursor != null;
        mRowIdColumn = mDataValid ? mCursor.getColumnIndex("_id") : -1;
        mDataSetObserver = new NotifyingDataSetObserver(this);
        if (mCursor != null) {
            mCursor.registerDataSetObserver(mDataSetObserver);
        }
    }

    public Cursor getCursor() {
        return mCursor;
    }

    @Override
    public int getItemCount() {
        if (mDataValid && mCursor != null) {
            return mCursor.getCount();
        }
        return 0;
    }

    @Override
    public long getItemId(int position) {
        if (mDataValid && mCursor != null && mCursor.moveToPosition(position)) {
            return mCursor.getLong(mRowIdColumn);
        }
        return 0;
    }

    @Override
    public void setHasStableIds(boolean hasStableIds) {
        super.setHasStableIds(true);
    }

    public static final String TAG = CursorRecyclerViewAdapter.class.getSimpleName();

    public abstract void onBindViewHolder(VH viewHolder, Cursor cursor);

    @Override
    public VH onCreateViewHolder(ViewGroup parent, int viewType) {
        return null;
    }

    @Override
    public void onBindViewHolder(VH viewHolder, int position) {
        if (!mDataValid) {
            throw new IllegalStateException("this should only be called when the cursor is valid");
        }
        if (!mCursor.moveToPosition(position)) {
            throw new IllegalStateException("couldn't move cursor to position " + position);
        }
        onBindViewHolder(viewHolder, mCursor);
    }

    /**
     * Change the underlying cursor to a new cursor. If there is an existing cursor it will be
     * closed.
     */
    public void changeCursor(Cursor cursor) {
        Cursor old = swapCursor(cursor);
        if (old != null) {
            old.close();
        }
    }

    /**
     * Swap in a new Cursor, returning the old Cursor.  Unlike
     * {@link #changeCursor(Cursor)}, the returned old Cursor is <em>not</em>
     * closed.
     */
    public Cursor swapCursor(Cursor newCursor) {
        if (newCursor == mCursor) {
            return null;
        }
        final Cursor oldCursor = mCursor;
        if (oldCursor != null && mDataSetObserver != null) {
            oldCursor.unregisterDataSetObserver(mDataSetObserver);
        }
        mCursor = newCursor;
        if (mCursor != null) {
            if (mDataSetObserver != null) {
                mCursor.registerDataSetObserver(mDataSetObserver);
            }
            mRowIdColumn = newCursor.getColumnIndexOrThrow("_id");
            mDataValid = true;
            notifyDataSetChanged();
        } else {
            mRowIdColumn = -1;
            mDataValid = false;
            notifyDataSetChanged();
            //There is no notifyDataSetInvalidated() method in RecyclerView.Adapter
        }
        return oldCursor;
    }

    public void setDataValid(boolean mDataValid) {
        this.mDataValid = mDataValid;
    }

    private class NotifyingDataSetObserver extends DataSetObserver {
        private RecyclerView.Adapter adapter;

        public NotifyingDataSetObserver(RecyclerView.Adapter adapter) {
            this.adapter = adapter;
        }

        @Override
        public void onChanged() {
            super.onChanged();
            ((CursorRecyclerViewAdapter) adapter).setDataValid(true);
            adapter.notifyDataSetChanged();
        }

        @Override
        public void onInvalidated() {
            super.onInvalidated();
            ((CursorRecyclerViewAdapter) adapter).setDataValid(false);
        }
    }
}

Step 5. create your own adapter with extending(inheriting) previous class

import android.content.Context;
import android.database.Cursor;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * Created by deadfish on 2016-01-28.
 */
public class CustomCursorRecyclerViewAdapter extends CursorRecyclerViewAdapter {

    public CustomCursorRecyclerViewAdapter(Context context, Cursor cursor) {
        super(context, cursor);
    }

    @Override
    public long getItemId(int position) {
        return super.getItemId(position);
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(mContext).inflate(android.R.layout.simple_list_item_1, parent, false);
        return new CustomViewHolder(v);
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, Cursor cursor) {
        CustomViewHolder holder = (CustomViewHolder) viewHolder;
        cursor.moveToPosition(cursor.getPosition());
        holder.setData(cursor);
    }

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

    @Override
    public int getItemViewType(int position) {
        return 0;
    }
}

Step 6. create custom viewHolder

import android.database.Cursor;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.TextView;

public class CustomViewHolder extends RecyclerView.ViewHolder {

    public TextView textView1;

    public CustomViewHolder(View itemView) {
        super(itemView);
        textView1 = (TextView) itemView.findViewById(android.R.id.text1);
    }

    public void setData(Cursor c) {
        textView1.setText(c.getString(c.getColumnIndex("text")));
    }
}

Step 7. write code in sample MainActivity

import android.content.ContentValues;
import android.database.Cursor;
import android.database.MatrixCursor;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.app.LoaderManager;
import android.support.v4.content.CursorLoader;
import android.support.v4.content.Loader;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.widget.Toast;

import com.example.pagingproject.adapters.CustomCursorRecyclerViewAdapter;
import com.example.pagingproject.databases.RequestProvider;
import com.example.pagingproject.databases.TableItems;

public class MainActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<Cursor> {

    public final int offset = 30;
    private int page = 0;

    private RecyclerView mRecyclerView;
    private boolean loadingMore = false;
    private Toast shortToast;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        LinearLayoutManager mLayoutManager = new LinearLayoutManager(this);
        CustomCursorRecyclerViewAdapter mAdapter = new CustomCursorRecyclerViewAdapter(this, null);

        mRecyclerView = (RecyclerView) findViewById(R.id.recyclerView);
        mRecyclerView.setLayoutManager(mLayoutManager);
        mRecyclerView.setAdapter(mAdapter);

        int itemsCountLocal = getItemsCountLocal();
        if (itemsCountLocal == 0) {
            fillTestElements();
        }

        shortToast = Toast.makeText(this, "", Toast.LENGTH_SHORT);

        mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);

                LinearLayoutManager layoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
                int lastVisibleItemPosition = layoutManager.findLastVisibleItemPosition();
                int maxPositions = layoutManager.getItemCount();

                if (lastVisibleItemPosition == maxPositions - 1) {
                    if (loadingMore)
                        return;

                    loadingMore = true;
                    page++;
                    getSupportLoaderManager().restartLoader(0, null, MainActivity.this);
                }
            }
        });

        getSupportLoaderManager().restartLoader(0, null, this);
    }

    private void fillTestElements() {
        int size = 1000;
        ContentValues[] cvArray = new ContentValues[size];
        for (int i = 0; i < cvArray.length; i++) {
            ContentValues cv = new ContentValues();
            cv.put(TableItems.TEXT, ("text " + i));
            cvArray[i] = cv;
        }

        getContentResolver().bulkInsert(RequestProvider.urlForItems(0), cvArray);
    }

    private int getItemsCountLocal() {
        int itemsCount = 0;

        Cursor query = getContentResolver().query(RequestProvider.urlForItems(0), null, null, null, null);
        if (query != null) {
            itemsCount = query.getCount();
            query.close();
        }
        return itemsCount;
    }

    /*loader*/

    @Override
    public Loader<Cursor> onCreateLoader(int id, Bundle args) {
        switch (id) {
            case 0:
                return new CursorLoader(this, RequestProvider.urlForItems(offset * page), null, null, null, null);
            default:
                throw new IllegalArgumentException("no id handled!");
        }
    }

    @Override
    public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
        switch (loader.getId()) {
            case 0:
                Log.d(TAG, "onLoadFinished: loading MORE");
                shortToast.setText("loading MORE " + page);
                shortToast.show();

                Cursor cursor = ((CustomCursorRecyclerViewAdapter) mRecyclerView.getAdapter()).getCursor();

                //fill all exisitng in adapter
                MatrixCursor mx = new MatrixCursor(TableItems.Columns);
                fillMx(cursor, mx);

                //fill with additional result
                fillMx(data, mx);

                ((CustomCursorRecyclerViewAdapter) mRecyclerView.getAdapter()).swapCursor(mx);


                handlerToWait.postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        loadingMore = false;
                    }
                }, 2000);

                break;
            default:
                throw new IllegalArgumentException("no loader id handled!");
        }
    }

    private Handler handlerToWait = new Handler();

    private void fillMx(Cursor data, MatrixCursor mx) {
        if (data == null)
            return;

        data.moveToPosition(-1);
        while (data.moveToNext()) {
            mx.addRow(new Object[]{
                    data.getString(data.getColumnIndex(TableItems._ID)),
                    data.getString(data.getColumnIndex(TableItems.TEXT))
            });
        }
    }

    @Override
    public void onLoaderReset(Loader<Cursor> loader) {
        // TODO: 2016-10-13
    }

    //

    private static final String TAG = "MainActivity";

}

Step 8. declare provider in AndroidManifest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.pagingproject">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <provider
            android:name=".databases.RequestProvider"
            android:authorities="${applicationId}.db"
            android:exported="false" />
    </application>

</manifest>

Step 9. create xml for MainActivity class

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.pagingproject.MainActivity">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</RelativeLayout>

Test it:

Trigger to load more is every 30th item element, so if index starts from 0, 29 will be the trigger.

Thank you for your answer :) :) I'm just trying to implement. I will let you know if I get any problem. — Pratik Butani, Oct 15 '16 at 04:22
Hello, Appreciated. :) Thank you. I have one question, If I want to implement two layout for recyclerview like *list* and *grid* then how can I do with this adapter. — Pratik Butani, Oct 18 '16 at 05:18
Try replace `LinearLayoutManager mLayoutManager = new LinearLayoutManager(this);` to `GridLayoutManager mLayoutManager = new GridLayoutManager(this, 2);` — deadfish, Oct 18 '16 at 07:24
I have used `StaggeredGridLayoutManager` and I have to change layout runtime from **one column to two columns**, How it will be possible in this case? — Pratik Butani, Oct 18 '16 at 07:26

score 3 · Answer 2 · answered Oct 13 '16 at 09:45

3

Recently, I created a TodoApp which contains most of the required features. link here

The app contains following relevant features:

1) Custom RecyclerView with Cursor support.

2) Content Provider to do basic CRUD operations on the SQLite database.

3) AsyncQueryHandler to easily interact with the Content Provider.

4) CursorLoader which updates the RecyclerView as soon as the underlying database changes.

The only thing that remains is implementing load more functionality. Codepath has a very good article on RecyclerView with Load More. (Let me know if any kind of help is required on this :) )

answered Oct 13 '16 at 09:45

Sarthak Mittal

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Thank for you answer, As per my requirement, How to initLoader call again for new data when load more data called? – Pratik Butani Oct 13 '16 at 09:55
Are you asking when you have to call your initLoader again once more items are loaded? AsyncQueryHandler gives callback methods whenever we do any operation. you can get a callback when you have fetched more items from your database. (or more precisely, when you have got the updated cursor with more items) – Sarthak Mittal Oct 13 '16 at 10:02
@PratikButani just checkout the AsyncQueryListener interface within the class: https://github.com/mrdevilbynature/TodoApp/blob/master/app/src/main/java/com/showcase/todoapp/database/QueryHandler.java – Sarthak Mittal Oct 13 '16 at 10:04
forgot to mention one small thing. In case you are wondering how to re-initialize your loader once you get the updated cursor callback: there is a method called restartLoader() in LoaderManager class: just call getLoaderManager().restartLoader(/*arguments*/); – Sarthak Mittal Oct 13 '16 at 11:01

Android RecyclerView + CursorLoader + ContentProvider + "Load More"

UPDATE:

Edited (ADAPTER Code):

2 Answers2

Linked