We are using lots of apps that load data while we scrolling. Facebook, Instagram, and more apps using this technique. This technique helps users to wait less time.

So if you are planning to make an app like that, using RecyclerView. Then this post is for you.

In this post, You will learn how to use Load More on Scroll or pagination or endless scrolling or infinite scroll or whatever you call, with RecyclerView.

Before that, I recommend reading our RecyclerView Tutorial Guide.

• Best Android Development Ebook For Visual Learners

This post is not dealing with the pagination library.

How To Implement Pagination In Android RecyclerView

In this post, I am going to talk about two methods, that implement pagination in RecyclerView. But in both methods, we will use scroll Listener with RecyclerView to listen to scroll events. When RecyclerView scrolls, onScrolled() method gets called.

So first learn how to add OnScrollListener with Recyclerview.

How To Add OnScrollListener With RecyclerView

    //attaches scrollListener with RecyclerView
        recyclerview.addOnScrollListener(object : RecyclerView.OnScrollListener()
        {
            override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int)
            {
                super.onScrolled(recyclerView, dx, dy)

              

            }
            })

    //attaches scrollListener with RecyclerView
        recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy)
            {
                super.onScrolled(recyclerView, dx, dy);
            }
        });

Simple Android RecyclerView Load More On Scroll Example

Let’s make a linear list Using RecyclerView and add an endless scroll feature.

After the implementation of scroll listener, we should do the following

• we use findLastCompletelyVisibleItemPosition() to get the position of last visible item.
• Use a variable which checks progressbar loading or not
• If last item reached and progressbar not loading, loadmore() gets called. Using Handler, we add “load” in list.
• When adapter checks list, ProgressBar gets added.
• Next data chunks received, ProgressBar gets removed and data got added.
• For showing different View types. here
  1. Data row
  2. ProgressBar

  Make use of getViewType() method in RecyclerView.Adapter.

MainActivity.kt

class MainActivity : AppCompatActivity()
{
    //handler instance
    var handler: Handler = Handler()
    //list for holding data
    lateinit var list : ArrayList

    lateinit var adapter : RecyclerViewAdapter
    //Variable for checking progressbar loading or not
    private var isLoading: Boolean = false
    lateinit var layoutManager : LinearLayoutManager



    override fun onCreate(savedInstanceState: Bundle?)
    {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        layoutManager = LinearLayoutManager(this)
        //attaches LinearLayoutManager with RecyclerView
        recyclerview.layoutManager = layoutManager

        list = ArrayList()

        load()

        adapter = RecyclerViewAdapter(list)

        recyclerview.adapter = adapter

        addScrollerListener()

    }

    private fun addScrollerListener()
    {
        //attaches scrollListener with RecyclerView
        recyclerview.addOnScrollListener(object : RecyclerView.OnScrollListener()
        {
            override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int)
            {
                super.onScrolled(recyclerView, dx, dy)

                if (!isLoading)
                {
                    //findLastCompletelyVisibleItemPostition() returns position of last fully visible view.
                    ////It checks, fully visible view is the last one.
                    if (layoutManager.findLastCompletelyVisibleItemPosition() == list.size - 1)
                    {

                        loadMore()
                        isLoading = true

                    }
                }

            }
            })
    }

    private fun loadMore()
    {
        //notify adapter using Handler.post() or RecyclerView.post()
        handler.post(Runnable
        {
            list.add("load")
            adapter.notifyItemInserted(list.size - 1)

        })

        handler.postDelayed(Runnable {

            //removes "load".
            list.removeAt(list.size - 1)
            var listSize = list.size

            adapter.notifyItemRemoved(listSize)
            //sets next limit
            var nextLimit = listSize + 10

            for(i in listSize until nextLimit)
            {
                list.add("Item No $i")
            }

            adapter.notifyDataSetChanged()
            isLoading = false

        },2500)
    }


    private fun load()
    {
        for(i in 0..9)
        {
            list.add("Item No: $i")
        }
    }

}

public class MainActivity extends AppCompatActivity
{
    RecyclerView recyclerView;
    RecyclerViewAdapter recyclerViewAdapter;

    ArrayList dataList = new ArrayList<>();
    LinearLayoutManager layoutManager;
    //handler object
    Handler handler = new Handler();
    //variable holding state of progressbar. It loads or not
    boolean isLoading = false;

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

        recyclerView = (RecyclerView)findViewById(R.id.recyclerView);

        load();

        layoutManager = new LinearLayoutManager(this);
        recyclerView.setLayoutManager(layoutManager);

        recyclerViewAdapter = new RecyclerViewAdapter(dataList);
        recyclerView.setAdapter(recyclerViewAdapter);

        addScrollerListener();
    }

    private void addScrollerListener()
    {
        //attaches scrollListener with RecyclerView
        recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy)
            {
                super.onScrolled(recyclerView, dx, dy);

                if(!isLoading)
                {

                     //findLastCompletelyVisibleItemPostition() returns position of last fully visible view.
                    //It checks, fully visible view is the last one.
                    if(layoutManager.findLastCompletelyVisibleItemPosition() == dataList.size() - 1)
                    {
                        loadMore();
                        isLoading = true;
                    }
                }

            }
        });
    }

    private void loadMore()
    {
        //notify adapter using Handler.post() or RecyclerView.post()
        handler.post(new Runnable() {
            @Override
            public void run()
            {
                dataList.add("load");
                recyclerViewAdapter.notifyItemInserted(dataList.size() - 1);
            }
        });


        handler.postDelayed(new Runnable()
        {
            @Override
            public void run()
            {
                //removes "load".
                dataList.remove(dataList.size() - 1);
                int listSize = dataList.size();

                recyclerViewAdapter.notifyItemRemoved(listSize);
                //sets next limit
                int nextLimit = listSize + 10;

                for(int itemCount = listSize; itemCount < nextLimit;  itemCount++)
                {
                    dataList.add("Item No "+ itemCount);
                }

                recyclerViewAdapter.notifyDataSetChanged();
                isLoading = false;
            }
        },2500);
    }

    private void load()
    {
        for(int i=0; i<10; i++)
        {
            dataList.add("Item No: "+i);
        }
    }
}

• It's better to use Handler.post() or RecyclerView.post() while updating adapter when RecyclerView measures.
• findLastCompletelyVisibleItemPosition() returns only completely visible Item's position, So make sure your last view is fully visible.
• 2500 milliseconds - delay time

RecyclerViewAdapter.kt

package m.example.simplerecyclerviewloadmoreex_kotlin

import androidx.recyclerview.widget.RecyclerView
import kotlinx.android.synthetic.main.row.view.*

import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Toast
import java.lang.IllegalArgumentException

class RecyclerViewAdapter(var list: ArrayList<String>) : RecyclerView.Adapter<RecyclerView.ViewHolder>()
{
    companion object
    {
        private const val VIEW_TYPE_DATA = 0;
        private const val VIEW_TYPE_PROGRESS = 1;
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewtype: Int): RecyclerView.ViewHolder
    {
        return when (viewtype)
        {
            VIEW_TYPE_DATA ->
            {//inflates row layout
                val view = LayoutInflater.from(parent.context).inflate(R.layout.row,parent,false)
                DataViewHolder(view)
            }

            VIEW_TYPE_PROGRESS ->
            {//inflates progressbar layout
                val view = LayoutInflater.from(parent.context).inflate(R.layout.progressbar,parent,false)
                ProgressViewHolder(view)
            }
            else -> throw IllegalArgumentException("Different View type")

        }
    }

    override fun getItemCount(): Int
    {
        return list.size
    }

    override fun getItemViewType(position: Int): Int
    {
        var viewtype = list.get(position)

        return when(viewtype)
        {//if data is load, returns PROGRESSBAR viewtype.
            "load"  -> VIEW_TYPE_PROGRESS
            else -> VIEW_TYPE_DATA
        }
    }

    override fun onBindViewHolder(holder: RecyclerView.ViewHolder, p1: Int)
    {

        if (holder is DataViewHolder)
        {
            holder.textview.text = list.get(p1)
        }
    }

    inner class DataViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView)
    {
        var textview = itemView.textview

        init {
            itemView.setOnClickListener {
                Toast.makeText(itemView.context,list.get(adapterPosition),Toast.LENGTH_LONG).show()
            }
        }
    }

    inner class ProgressViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView)

}

package com.androidride;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.List;

public class RecyclerViewAdapter extends RecyclerView.Adapter
{
    public static final int VIEW_TYPE_DATA = 0;
    public static final int VIEW_TYPE_PROGRESS = 1;

    public List dataList;

    public RecyclerViewAdapter(List dataList)
    {
        this.dataList = dataList;
    }
    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewtype)
    {
        if(viewtype == VIEW_TYPE_DATA)
        {//inflates row layout.
            View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.row,viewGroup,false);
            return new DataViewHolder(view);
        }
        else
        {//inflates progressbar layout.
            View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.progressbar,viewGroup,false);
            return new ProgressViewHolder(view);
        }
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder viewHolder, int i)
    {
        if(viewHolder instanceof DataViewHolder)
        {
            ((DataViewHolder) viewHolder).textView.setText(dataList.get(i));
        }
    }

    @Override
    public int getItemViewType(int position)
    {//if data is load, returns Progressbar viewtype.
        return dataList.get(position) == "load" ? VIEW_TYPE_PROGRESS : VIEW_TYPE_DATA;
    }

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


    class DataViewHolder extends RecyclerView.ViewHolder
    {
        TextView textView;

        public DataViewHolder(@NonNull View itemView)
        {
            super(itemView);
            textView = (TextView)itemView.findViewById(R.id.textview);

            itemView.setOnClickListener(new View.OnClickListener()
            {
                @Override
                public void onClick(View view)
                {
                    Toast.makeText(view.getContext(), dataList.get(getAdapterPosition()), Toast.LENGTH_SHORT).show();
                }
            });

        }
    }

    class ProgressViewHolder extends RecyclerView.ViewHolder
    {
        ProgressBar progressBar;

        public ProgressViewHolder(@NonNull View itemView)
        {
            super(itemView);
            progressBar = (ProgressBar)itemView.findViewById(R.id.progressBar);

        }
    }
}

• getItemViewType(int position) method returns VIEW_TYPE_PROGRESS, if data is "load". Otherwise, it returns VIEW_TYPE_DATA.
• Based on ViewType, In onCreateViewHolder layout will get inflated.

Grid RecyclerView Pagination Example - Different Approach

Now we will make a Grid RecyclerView with pagination. Sometimes we need to load data before the last item loads.

For that purpose, you can make use of this approach.

Okay, what we do in this approach.

we define 3 variables, visibleThreshold, lastVisibleItem, and totalItemCount.

• visibleThreshold : limit of items that user want to see before loading next items
• lastVisibleItem : just like name, last visible item position in adapter
• totalItemCount : No.of items in adapter

after the scroll listener setup,

• When onScrolled() gets called, just checks totalItemCount <= lastVisibleItem + visibleThreshold with isLoading : variable for storing progressbar state.
• if both are true, next chunks of data get loaded

class MainActivity : AppCompatActivity()
{
    lateinit var list : ArrayList
    lateinit var adapter : RecyclerViewAdapter
    private var isLoading: Boolean = false
    lateinit var gridlayoutManager : GridLayoutManager


    private var visibleThreshold = 5
    private var lastVisibleItem = 0
    private var totalItemCount = 0

    //handler instance
    private var handler: Handler = Handler()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        //no of columns or span in the grid.
        var columns = 2

        gridlayoutManager = GridLayoutManager(this, columns)
        recyclerview.layoutManager = gridlayoutManager

        load()

        adapter = RecyclerViewAdapter(list)

        recyclerview.adapter = adapter

        addScrollerListener()

        gridlayoutManager.spanSizeLookup = object : GridLayoutManager.SpanSizeLookup()
        {
            //Each item occupies 1 span by default.
            override fun getSpanSize(p0: Int): Int
            {
                return when (adapter.getItemViewType(p0))
                {
                    //returns total no of spans, to occupy full sapce for progressbar
                    RecyclerViewAdapter.VIEW_TYPE_PROGRESS -> gridlayoutManager.spanCount
                    RecyclerViewAdapter.VIEW_TYPE_DATA -> 1
                    else -> -1
                }
            }
        }
    }

      private  fun addScrollerListener()
        {
            recyclerview.addOnScrollListener(object : RecyclerView.OnScrollListener()
            {
                override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int)
                {
                    super.onScrolled(recyclerView, dx, dy)

                    //total no. of items
                    totalItemCount = gridlayoutManager.itemCount
                    //last visible item position
                    lastVisibleItem = gridlayoutManager.findLastCompletelyVisibleItemPosition()

                    if(!isLoading && totalItemCount <= (lastVisibleItem + visibleThreshold))
                    {
                        loadMore()
                        isLoading = true
                    }
                }
            })
        }



    private fun loadMore()
    {
        handler.post(Runnable
        {
            //adds load item in list
            list.add("load")
            adapter.notifyItemInserted(list.size - 1)

        })

        recyclerview.postDelayed(Runnable {

            //removes load item in list.
            list.removeAt(list.size - 1)
            var listSize = list.size

            adapter.notifyItemRemoved(listSize)
            //next limit
            var nextLimit = listSize + 10

            for(i in listSize until nextLimit)
            {
                list.add("Item No $i")
            }

            adapter.notifyDataSetChanged()
            isLoading = false

        },7000)

    }

    private fun load()
    {
        list = ArrayList()

        for(i in 0..9)
        {
            list.add("Item $i")
        }
    }

}

public class MainActivity extends AppCompatActivity
{
    RecyclerView recyclerView;
    RecyclerViewAdapter adapter;
    boolean isLoading = false;
    private int visibleThreshold = 5;
    private int lastVisibleItem, totalItemCount;
    //handler reference
    Handler handler;
    ArrayList data;

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

        createData();
        recyclerView = (RecyclerView)findViewById(R.id.recyclerview);
        adapter = new RecyclerViewAdapter(data);


        recyclerView.setAdapter(adapter);

        //no of columns or span in the grid.
        int columns = 2;
        final GridLayoutManager gridLayoutManager = new GridLayoutManager(this,columns);

        recyclerView.setLayoutManager(gridLayoutManager);


        gridLayoutManager.setSpanSizeLookup(
                new GridLayoutManager.SpanSizeLookup()
                {
                    //Each item occupies 1 span by default. You can change it using setSpanSizeLookUp
                    @Override
                    public int getSpanSize(int i)
                    {
                        switch (adapter.getItemViewType(i))
                        {
                            //returns total no of spans, to occupy full sapce for progressbar
                            case RecyclerViewAdapter.VIEW_TYPE_PROGRESS: return gridLayoutManager.getSpanCount();
                            case  RecyclerViewAdapter.VIEW_TYPE_ITEM: return  1;
                            default: return -1;
                        }
                    }
                });


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

                //total no. of items
                totalItemCount = gridLayoutManager.getItemCount();
                //last visible item position
                lastVisibleItem = gridLayoutManager.findLastCompletelyVisibleItemPosition();

                if (!isLoading&& totalItemCount <= (lastVisibleItem + visibleThreshold))
                {
                    loadMore();
                    isLoading = true;
                }
            }
        });

    }





    private void loadMore()
    {
        Handler handler = new Handler();
        handler.post(new Runnable() {
            @Override
            public void run()
            {
                //adds load item in list
                data.add("load");
                adapter.notifyItemInserted(data.size() - 1);
            }
        });



        handler.postDelayed(new Runnable()
        {
            @Override
            public void run()
            {
                //removes load item in list.
                data.remove(data.size() - 1);
                int listSize = data.size();
                adapter.notifyItemRemoved(listSize);
                //next limit
                int nextLimit = listSize + 10;

                while(listSize < nextLimit)
                {
                    data.add("Item " + (listSize + 1));
                    listSize++;
                }

                adapter.notifyDataSetChanged();
                isLoading = false;

            }
        },7000);


    }

    private void createData()
    {
        data = new ArrayList<>();

        for (int i=0; i<10;i++)
        {
            data.add(" item "+i);
        }
    }


}

• Make ProgressBar width to maximum using setSpanSizeLookup() method

RecyclerViewAdapter.kt

class RecyclerViewAdapter(var list: ArrayList<String>) : RecyclerView.Adapter<RecyclerView.ViewHolder>()
{
    companion object
    {
        const val VIEW_TYPE_DATA = 0;
        const val VIEW_TYPE_PROGRESS = 1;
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewtype: Int): RecyclerView.ViewHolder
    {
        return when (viewtype)
        {
            VIEW_TYPE_DATA ->
            {
                val view = LayoutInflater.from(parent.context).inflate(R.layout.row,parent,false)
                DataViewHolder(view)
            }

            VIEW_TYPE_PROGRESS ->
            {
                val view = LayoutInflater.from(parent.context).inflate(R.layout.progressbar,parent,false)
                ProgressViewHolder(view)
            }
            else -> throw IllegalArgumentException("Different View type")

        }
    }

    override fun getItemCount(): Int
    {
        return list.size
    }

    override fun getItemViewType(position: Int): Int
    {
        var viewtype = list.get(position)
        return when(viewtype)
        {
            "load"  -> VIEW_TYPE_PROGRESS
            else -> VIEW_TYPE_DATA
        }
    }

    override fun onBindViewHolder(p0: RecyclerView.ViewHolder, p1: Int)
    {

        if (p0 is DataViewHolder)
        {
            p0.textview.text = list.get(p1)
        }
    }

    inner class DataViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView)
    {
        var textview = itemView.textview

        init {
            itemView.setOnClickListener {
                Toast.makeText(itemView.context,list.get(adapterPosition),Toast.LENGTH_LONG).show()
            }
        }
    }

    inner class ProgressViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView)
    
}

class RecyclerViewAdapter(var list: ArrayList) : RecyclerView.Adapter()
{
    companion object
    {
        const val VIEW_TYPE_DATA = 0;
        const val VIEW_TYPE_PROGRESS = 1;
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewtype: Int): RecyclerView.ViewHolder
    {
        return when (viewtype)
        {
            VIEW_TYPE_DATA ->
            {
                val view = LayoutInflater.from(parent.context).inflate(R.layout.row,parent,false)
                DataViewHolder(view)
            }

            VIEW_TYPE_PROGRESS ->
            {
                val view = LayoutInflater.from(parent.context).inflate(R.layout.progressbar,parent,false)
                ProgressViewHolder(view)
            }
            else -> throw IllegalArgumentException("Different View type")

        }
    }

    override fun getItemCount(): Int
    {
        return list.size
    }

    override fun getItemViewType(position: Int): Int
    {
        var viewtype = list.get(position)
        return when(viewtype)
        {
            "load"  -> VIEW_TYPE_PROGRESS
            else -> VIEW_TYPE_DATA
        }
    }

    override fun onBindViewHolder(p0: RecyclerView.ViewHolder, p1: Int)
    {

        if (p0 is DataViewHolder)
        {
            p0.textview.text = list.get(p1)
        }
    }

    inner class DataViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView)
    {
        var textview = itemView.textview

        init {
            itemView.setOnClickListener {
                Toast.makeText(itemView.context,list.get(adapterPosition),Toast.LENGTH_LONG).show()
            }
        }
    }

    inner class ProgressViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView)

}

Retrofit Android RecyclerView Infinite Scroll Example

In this example, we will load data from the internet using Retrofit2. You can download PHP(data.php) code from the Source Code link shown at the top.

I am using Android Studio 3.5.

Let's create a project.

In choosing your project window, click on "Empty Activity" and click Next.

Name: RetrofitRecyclerViewLoadMoreEx

Package name: androidride.com

Select language Kotlin

I am going to use AndroidX library, so make sure you tick on the androidx.* artifacts.
That's your choice, but I recommend to use this one.

Click "Finish".

add below dependencies

implementation 'com.squareup.retrofit2:retrofit:2.0.2'
implementation 'com.squareup.retrofit2:converter-gson:2.0.2'

implementation 'androidx.cardview:cardview:1.0.0'
implementation 'androidx.recyclerview:recyclerview:1.1.0'

• Gson converter : It helps to serialize and deserialize JSON data.

build.gradle(Module:App)

apply plugin: 'com.android.application'

apply plugin: 'kotlin-android'

apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion 28
    buildToolsVersion "29.0.2"
    defaultConfig {
        applicationId "com.androidride.retrofitrecyclerviewloadmoreex"
        minSdkVersion 15
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'androidx.core:core-ktx:1.2.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test:runner:1.2.0'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'


    implementation 'com.squareup.retrofit2:retrofit:2.0.2'
    implementation 'com.squareup.retrofit2:converter-gson:2.0.2'

    implementation 'androidx.cardview:cardview:1.0.0'
    implementation 'androidx.recyclerview:recyclerview:1.1.0'

}

colors.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="colorPrimary">#008577</color>
    <color name="colorPrimaryDark">#00574B</color>
    <color name="colorAccent">#D81B60</color>
</resources>

strings.xml

<resources>
    <string name="app_name">Retrofit RecyclerView LoadMore Ex - Kotlin</string>
</resources>

styles.xml

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>

</resources>

• Don't forget to add INTERNET permission in AndroidManifest.xml like below

AndroidManifest.xml

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

    <uses-permission android:name="android.permission.INTERNET"/>

    <application
            android:allowBackup="true"
            android:icon="@mipmap/ic_launcher"
            android:label="@string/app_name"
            android:roundIcon="@mipmap/ic_launcher_round"
            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>
    </application>

</manifest>

Data.kt

package com.androidride.retrofitrecyclerviewloadmoreex

data class Data(var category: String)
{
    var title: String? = null
    var subtitle: String? = null

    init {
        this.category = category
    }
}

package com.androidride.retrofitrecyclerviewloadmoreex;

public class Data
{
 String title, subtitle, category;

  Data(String category)
  {
   this.category = category;
  }
}

DataApi.kt

package com.androidride.retrofitrecyclerviewloadmoreex

import retrofit2.Call
import retrofit2.http.GET
import retrofit2.http.Query

interface DataApi
{
@GET("data.php")
fun getData(@Query("index") index : Int): Call<List<Data>>
}

package com.androidride.retrofitrecyclerviewloadmoreex;

import java.util.List;

import retrofit2.Call;
import retrofit2.http.GET;
import retrofit2.http.Query;

public interface DataApi
{
    @GET("data.php")
    Call> getData(@Query("index") int index);
}

• In Retrofit2, endpoints defined in Interface with special annotations.
• This endpoint returns List.

MainActivity.kt

package com.androidride.retrofitrecyclerviewloadmoreex

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Toast
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import kotlinx.android.synthetic.main.activity_main.*
import retrofit2.Call
import retrofit2.Callback
import retrofit2.Response
import retrofit2.Retrofit


class MainActivity : AppCompatActivity()
{
    lateinit var list: ArrayList
    lateinit var adapter: RecyclerViewAdapter

    var notLoading = true
    lateinit var layoutManager: LinearLayoutManager
    lateinit var api: DataApi
    lateinit var retrofit: Retrofit


    override fun onCreate(savedInstanceState: Bundle?)
    {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)


        list = ArrayList()
        adapter = RecyclerViewAdapter(list)
        recyclerview.setHasFixedSize(true)

        layoutManager = LinearLayoutManager(this)
        recyclerview.layoutManager = layoutManager
        recyclerview.adapter = adapter

        retrofit = RetrofitInstance.getRetrofitInstance()
        api = retrofit.create(DataApi::class.java)

        load(0)

        addscrolllistener()
    }

    private fun addscrolllistener()
    {
        recyclerview.addOnScrollListener(object : RecyclerView.OnScrollListener()
        {
            override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int)
            {
                if(notLoading &&  layoutManager.findLastCompletelyVisibleItemPosition() == list.size -1 )
                {
                    list.add(Data("progress"))
                    adapter.notifyItemInserted(list.size - 1)
                    notLoading = false

                    val call: Call<List> = api.getData(list.size - 1)

                    call.enqueue( object :  Callback<List>
                    {
                        override fun onResponse(call: Call<List>?, response: Response<List>?)
                        {
                        list.removeAt(list.size - 1)
                        adapter.notifyItemRemoved(list.size)

                                if(response!!.body().isNotEmpty())
                                {
                                    list.addAll(response.body())
                                    adapter.notifyDataSetChanged()
                                    notLoading = true
                                }
                                else
                                {
                                    Toast.makeText(applicationContext,"End of data reached", Toast.LENGTH_LONG).show()
                                }

                        }

                        override fun onFailure(call: Call<List>?, t: Throwable?) {
                            TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
                        }
                    })
                }
            }
        })
    }

    private fun load(i: Int)
    {
        val call: Call<List> = api.getData(0)

        call.enqueue(object : Callback<List>
        {
            override fun onResponse(call: Call<List>?, response: Response<List>?)
            {
                if(response!!.isSuccessful)
                {
                    list.addAll(response!!.body())
                    adapter.notifyDataSetChanged()
                }

            }

            override fun onFailure(call: Call<List>?, t: Throwable?)
            {

            }
        })

    }
}

package com.androidride.retrofitrecyclerviewloadmoreex

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Toast
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import kotlinx.android.synthetic.main.activity_main.*
import retrofit2.Call
import retrofit2.Callback
import retrofit2.Response
import retrofit2.Retrofit


class MainActivity : AppCompatActivity()
{
    lateinit var list: ArrayList
    lateinit var adapter: RecyclerViewAdapter

    var notLoading = true
    lateinit var layoutManager: LinearLayoutManager
    lateinit var api: DataApi
    lateinit var retrofit: Retrofit


    override fun onCreate(savedInstanceState: Bundle?)
    {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)


        list = ArrayList()
        adapter = RecyclerViewAdapter(list)
        recyclerview.setHasFixedSize(true)

        layoutManager = LinearLayoutManager(this)
        recyclerview.layoutManager = layoutManager
        recyclerview.adapter = adapter

        retrofit = RetrofitInstance.getRetrofitInstance()
        api = retrofit.create(DataApi::class.java)

        load(0)

        addscrolllistener()
    }

    private fun addscrolllistener()
    {
        recyclerview.addOnScrollListener(object : RecyclerView.OnScrollListener()
        {
            override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int)
            {
                if(notLoading &&  layoutManager.findLastCompletelyVisibleItemPosition() == list.size -1 )
                {
                    list.add(Data("progress"))
                    adapter.notifyItemInserted(list.size - 1)
                    notLoading = false

                    val call: Call<List> = api.getData(list.size - 1)

                    call.enqueue( object :  Callback<List>
                    {
                        override fun onResponse(call: Call<List>?, response: Response<List>?)
                        {
                        list.removeAt(list.size - 1)
                        adapter.notifyItemRemoved(list.size)

                                if(response!!.body().isNotEmpty())
                                {
                                    list.addAll(response.body())
                                    adapter.notifyDataSetChanged()
                                    notLoading = true
                                }
                                else
                                {
                                    Toast.makeText(applicationContext,"End of data reached", Toast.LENGTH_LONG).show()
                                }

                        }

                        override fun onFailure(call: Call<List>?, t: Throwable?) {
                            TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
                        }
                    })
                }
            }
        })
    }

    private fun load(i: Int)
    {
        val call: Call<List> = api.getData(0)

        call.enqueue(object : Callback<List>
        {
            override fun onResponse(call: Call<List>?, response: Response<List>?)
            {
                if(response!!.isSuccessful)
                {
                    list.addAll(response!!.body())
                    adapter.notifyDataSetChanged()
                }

            }

            override fun onFailure(call: Call<List>?, t: Throwable?)
            {

            }
        })

    }
}

RetrofitInstance.kt

package com.androidride.retrofitrecyclerviewloadmoreex

import retrofit2.Retrofit
import retrofit2.converter.gson.GsonConverterFactory

class RetrofitInstance
{
    companion object
    {
        fun getRetrofitInstance(): Retrofit
        {
            val retrofit = Retrofit.Builder().baseUrl("https://www.androidride.com/").addConverterFactory(
                GsonConverterFactory.create()).build()

            return retrofit

        }
    }
}

package com.androidride.retrofitrecyclerviewloadmoreex;

import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;

public class RetrofitInstance
{
    private static Retrofit retrofit;
    private static final String BASE_URL = "https://www.androidride.com/";

    public static Retrofit getRetrofitInstance()
    {
        if (retrofit == null)
        {
            retrofit = new retrofit2.Retrofit.Builder()
                    .baseUrl(BASE_URL)
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();
        }
        return retrofit;
    }
}

• For performing network requests, we need to create Retrofit Instance using Retrofit.Builder() using Base Url

RecyclerViewAdapter.kt

package com.androidride.retrofitrecyclerviewloadmoreex;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import org.w3c.dom.Text;

import java.util.ArrayList;

public class RecyclerViewAdapter extends RecyclerView.Adapter
{

    public static final int TYPE_DATA = 0;
    public static final int TYPE_PROGRESS = 1;

    ArrayList list;

        public RecyclerViewAdapter(Context context,ArrayList list)
        {
            this.list = list;
        }


    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType)
    {
        LayoutInflater inflater = LayoutInflater.from(parent.getContext());

            if(viewType == TYPE_DATA)
            {
                return new DataHolder(inflater.inflate(R.layout.row,parent,false));
            }
            else
            {
                return new ProgressHolder(inflater.inflate(R.layout.progressbar,parent,false));
            }

    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position)
    {
            if(holder instanceof  DataHolder)
            {
                ((DataHolder) holder).textTitle.setText(list.get(position).title);
                ((DataHolder) holder).textSubtitle.setText(list.get(position).subtitle);
            }
    }

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

    @Override
    public int getItemViewType(int position)
    {
        if(list.get(position).category.equals("data"))
        {
            return TYPE_DATA;
        }
        else
         {
            return TYPE_PROGRESS;
         }
    }

    class DataHolder extends RecyclerView.ViewHolder
    {
        TextView textTitle,textSubtitle;

        public DataHolder(@NonNull final View itemView)
        {
            super(itemView);

            textTitle =(TextView)itemView.findViewById(R.id.title);
            textSubtitle = (TextView)itemView.findViewById(R.id.subtitle);

            itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view)
                {
                    Toast.makeText(itemView.getContext(),"Clicked Item: "+list.get(getAdapterPosition()).subtitle,Toast.LENGTH_SHORT).show();
                }
            });
        }
    }

    class ProgressHolder extends RecyclerView.ViewHolder
    {
        public ProgressHolder(@NonNull View itemView)
        {
            super(itemView);
        }
    }
}

package com.androidride.retrofitrecyclerviewloadmoreex;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import org.w3c.dom.Text;

import java.util.ArrayList;

public class RecyclerViewAdapter extends RecyclerView.Adapter
{

    public static final int TYPE_DATA = 0;
    public static final int TYPE_PROGRESS = 1;

    ArrayList list;

        public RecyclerViewAdapter(Context context,ArrayList list)
        {
            this.list = list;
        }


    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType)
    {
        LayoutInflater inflater = LayoutInflater.from(parent.getContext());

            if(viewType == TYPE_DATA)
            {
                return new DataHolder(inflater.inflate(R.layout.row,parent,false));
            }
            else
            {
                return new ProgressHolder(inflater.inflate(R.layout.progressbar,parent,false));
            }

    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position)
    {
            if(holder instanceof  DataHolder)
            {
                ((DataHolder) holder).textTitle.setText(list.get(position).title);
                ((DataHolder) holder).textSubtitle.setText(list.get(position).subtitle);
            }
    }

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

    @Override
    public int getItemViewType(int position)
    {
        if(list.get(position).category.equals("data"))
        {
            return TYPE_DATA;
        }
        else
         {
            return TYPE_PROGRESS;
         }
    }

    class DataHolder extends RecyclerView.ViewHolder
    {
        TextView textTitle,textSubtitle;

        public DataHolder(@NonNull final View itemView)
        {
            super(itemView);

            textTitle =(TextView)itemView.findViewById(R.id.title);
            textSubtitle = (TextView)itemView.findViewById(R.id.subtitle);

            itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view)
                {
                    Toast.makeText(itemView.getContext(),"Clicked Item: "+list.get(getAdapterPosition()).subtitle,Toast.LENGTH_SHORT).show();
                }
            });
        }
    }

    class ProgressHolder extends RecyclerView.ViewHolder
    {
        public ProgressHolder(@NonNull View itemView)
        {
            super(itemView);
        }
    }
}

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Do you want to make Horizontal RecyclerView?

Before jumping into tutorial, I would recommend reading RecyclerView In Android : The Ultimate Guide.

In this post, I will teach you how to make Horizontal RecyclerView In Android with 4 ideas. In the end, we will create a Horizontal RecyclerView project too.

Okay… Let’s start.

RecyclerView uses LayoutManager class to arrange its items, so below we are going to use the LayoutManager class to make it work.

1. Horizontal RecyclerView Using LinearLayoutManager

This is the first and most commonly used option to make Horizontal RecyclerView. LinearLayoutManager provides a constructor that we can change the orientation of RecyclerView.

LinearLayoutManager(Context context, int orientation, boolean reverseLayout)

val layoutManager = LinearLayoutManager(this@MainActivity,LinearLayoutManager.HORIZONTAL,false)
recyclerview.layoutManager = layoutManager

 LinearLayoutManager layoutManager = new LinearLayoutManager(this,LinearLayoutManager.HORIZONTAL,false);
 recyclerview.setLayoutManager(layoutManager);

• Here, we use “this” because RecyclerView uses in MainActivity. If you are using RecyclerView in fragment, you can use getActivity()
• false : Do not reverse the layout.

2.Horizontal RecyclerView Using app:LayoutManager attribute

• app:layoutManager=”androidx.recyclerview.widget.LinearLayoutManager”: sets LayoutManger for RecyclerView.
• android:orientation=”horizontal” : Render RecyclerView in Horizontal.
• For support library users, Use this app:layoutManager=”android.support.v7.widget.LinearLayoutManager”.

3. Horizontal RecyclerView Using GridLayoutManager

In this part, we use GridLayoutManager for creating horizontal RecyclerView. Use the below one.

GridLayoutManager(Context context, int spanCount, int orientation, boolean reverseLayout)

spanCount: Number of rows or columns based on orientation.

  val gridLayoutManager = GridLayoutManager(this@MainActivity,1,GridLayoutManager.HORIZONTAL,false)
        recyclerview.layoutManager = gridLayoutManager

        GridLayoutManager gridLayoutManager = new GridLayoutManager(this,1,GridLayoutManager.HORIZONTAL,false);
        recyclerview.setLayoutManager(gridLayoutManager);

    app:layoutManager="androidx.recyclerview.widget.GridLayoutManager"
    android:orientation="horizontal"
    app:spanCount="1"

• For support library users, app:layoutManager=”android.support.v7.widget.GridLayoutManager”

4. Horizontal Recyclerview Using StaggeredGridLayoutManager

In this section we can use StaggeredGridLayoutManager constructor, shown below:

StaggeredGridLayoutManager(int spanCount, int orientation)

 val staggeredGridLayoutManager = StaggeredGridLayoutManager(1,StaggeredGridLayoutManager.HORIZONTAL)
        recyclerview.layoutManager = staggeredGridLayoutManager

        StaggeredGridLayoutManager staggeredGridLayoutManager = new StaggeredGridLayoutManager(1,StaggeredGridLayoutManager.HORIZONTAL);
        recyclerview.setLayoutManager(staggeredGridLayoutManager);

app:layoutManager="androidx.recyclerview.widget.StaggeredGridLayoutManager"
android:orientation="horizontal"
app:spanCount="1"

• For support library users, Use app:layoutManager=”android.support.v7.widget.StaggeredGridLayoutManager”/li>

.

Horizontal RecyclerView In Android – Main Example

Let’s create a horizontal RecyclerView…

Just like below

Open Android Studio and start a new Android Studio project.

Application name : Horizontal RecyclerView Android Example.

Company domain: androidride.com

Check to include Kotlin support.

Select minimum SDK:API 15 – Android 4.0.3 (Ice Cream Sandwich) and click Next.

Next dialog, Select Empty Activity and click Next.

Activity Name: MainActivity
Check Generate layout file

Layout Name: activity_main

If you are using the latest Android Studio versions, there will be a CheckBox with the text “Use androidx.* artifacts”. Make sure that’s checked, which creates our project with androidx library.
Click Finish.

build.gradle

apply plugin: 'com.android.application'

apply plugin: 'kotlin-android'

apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion 28
    buildToolsVersion "29.0.0"
    defaultConfig {
        applicationId "com.androidride.horizontalrecyclerviewandroidexample"
        minSdkVersion 15
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'androidx.core:core-ktx:1.1.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test:runner:1.2.0'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
    implementation 'androidx.recyclerview:recyclerview:1.1.0'


}

colors.xml

    #008577
    #00574B
    #D81B60

strings.xml

    Horizontal RecyclerView Android Example

styles.xml

activity_main.xml

MainActivity.kt

class MainActivity : AppCompatActivity()
{
    val dataList = ArrayList()

    lateinit var adapter : RecyclerViewAdapter

    override fun onCreate(savedInstanceState: Bundle?)
    {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        setupdata()

        adapter = RecyclerViewAdapter(dataList)


        //Using LinearLayoutManager

        val layoutManager = LinearLayoutManager(this@MainActivity,LinearLayoutManager.HORIZONTAL,false)
        recyclerview.layoutManager = layoutManager



        /*Horizontal RecyclerView using GridLayoutManager

        val gridLayoutManager = GridLayoutManager(this@MainActivity,1,GridLayoutManager.HORIZONTAL,false)
        recyclerview.layoutManager = gridLayoutManager

        */


        /*
            Horizontal RecyclerView using StaggeredGridLayoutManager

        val staggeredGridLayoutManager = StaggeredGridLayoutManager(1,StaggeredGridLayoutManager.HORIZONTAL)
        recyclerview.layoutManager = staggeredGridLayoutManager

         */

        recyclerview.adapter = adapter
    }


    private fun setupdata()
    {
        dataList.add("ONE")
        dataList.add("TWO")
        dataList.add("THREE")
        dataList.add("FOUR")
        dataList.add("FIVE")
        dataList.add("SIX")
        dataList.add("SEVEN")
        dataList.add("EIGHT")
        dataList.add("NINE")
        dataList.add("TEN")
    }
}

public class MainActivity extends AppCompatActivity
{

    private ArrayList dataList= new ArrayList<>();

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

        setupdata();

        recyclerview = (RecyclerView)findViewById(R.id.recyclerview);

        RecyclerViewAdapter adapter = new RecyclerViewAdapter(dataList);


        //Horizontal RecyclerView using LinearLayoutManager

       // LinearLayoutManager layoutManager = new LinearLayoutManager(this,LinearLayoutManager.HORIZONTAL,false);
        //recyclerview.setLayoutManager(layoutManager);

        /*
        Horizontal RecyclerView using GridLayoutManager

        GridLayoutManager gridLayoutManager = new GridLayoutManager(this,1,GridLayoutManager.HORIZONTAL,false);
        recyclerview.setLayoutManager(gridLayoutManager);

        */


        /*
        Horizontal RecyclerView using StaggeredGridLayoutManager

        StaggeredGridLayoutManager staggeredGridLayoutManager = new StaggeredGridLayoutManager(1,StaggeredGridLayoutManager.HORIZONTAL);
        recyclerview.setLayoutManager(staggeredGridLayoutManager);

        */
        recyclerview.setAdapter(adapter);
        }

    private void setupdata()
    {
        dataList.add("ONE");
        dataList.add("TWO");
        dataList.add("THREE");
        dataList.add("FOUR");
        dataList.add("FIVE");
        dataList.add("SIX");
        dataList.add("SEVEN");
        dataList.add("EIGHT");
        dataList.add("NINE");
        dataList.add("TEN");

    }


}

item.xml

RecyclerViewAdapter.kt

class RecyclerViewAdapter(val dataList: ArrayList):RecyclerView.Adapter()
{

        inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView)
        {
            val textview = itemView.textview
        }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder
    {
            val inflater = LayoutInflater.from(parent.context)
            val view = inflater.inflate(R.layout.item,parent,false)

            return ViewHolder(view)
    }

    override fun getItemCount(): Int
    {
        return dataList.size
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int)
    {
        holder.textview.text = dataList.get(position)
    }
}

public class RecyclerViewAdapter extends RecyclerView.Adapter
{
    ArrayList dataList = new ArrayList<>();

    public RecyclerViewAdapter(ArrayList dataList)
    {
        this.dataList = dataList;
    }

    class ViewHolder extends  RecyclerView.ViewHolder
    {
        TextView textview;
        public ViewHolder(@NonNull View itemView)
        {
            super(itemView);
            textview = (TextView)itemView.findViewById(R.id.textview);
        }
    }
    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType)
    {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item,parent,false);
        return  new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position)
    {
        holder.textview.setText(dataList.get(position));
    }

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

}

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• Easiest Way To Make ListView In Android

RecyclerView??? Is that a View? What does it do?

How to use this one?

are these thoughts running through your head? then Go on.
Or
you know something about RecyclerView then Refresh your knowledge by reading this post.

In this article, you will learn about RecyclerView, RecyclerView Adapter, and a simple example that helps you to create your one.
At last, I will teach you how to use Checkbox with RecyclerView. Yes, you can scroll fearlessly without thinking about losing the selected states in CheckBox.

So fasten your seatbelts, let’s take-off now.

• 3 Android RecyclerView Load More On Scroll Examples

What Is RecyclerView In Android?

From the name, we can understand that it’s an Android View. Actually, It is a ViewGroup with scroll ability which works based on adapter principles.

In simple words, It helps us to show a large no. of data collections just like ListView and GridView.

If RecyclerView wants to show large no.of items, it does not create the same amount of views. It just creates the viewholders which hold the inflated view needed to fill the screen and some more.

After that when the user scrolls, it makes use of cached views. Yes, It recycles views, again and again, that’s why it got the name “RecyclerView”.

As a successor, It is far away from ancestors(ListView, GridView) by performances and abilities. By more features, it becomes a little bit complex too.

Let’s look up the history, ListView has been part of Android since 1.0, but each os releases, new features got added. Not in the case of ListView.

ListView simply defeated by developer’s needs such as different types of layouts and animation support. That’s where RecyclerView was born.

Finally in 2014 Android Lolipop introduced RecyclerView as a standalone support library.

After the arrival of the AndroidX library (after API level 28.0.0), RecyclerView changed its package name android.support.v7.widget.RecyclerView to androidx.recyclerview.widget.RecyclerView.

If you are using Android Studio, just add it to gradle and use.

8 Differences Between ListView And RecyclerView In Android

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1. ViewHolder pattern
ViewHolder pattern is a strategy used to store view references in memory.

It reduces the number of calls to complicated and tedious findViewById(), which makes scrolling smooth.
,
In the case of ListView, it was optional, you can build your favorite list without any use of ViewHolder.

But when it comes to RecyclerView side, google developers make it as default for RecyclerView.

2. Re-Using views
Both ListView and RecyclerView support Reusing views. On the ListView side, it gives the option to reuse.

It’s the developer, who needs to take the action.

@Override
    public View getView(int position, View convertView, ViewGroup parent) 
{
     if(convertView == null)
     {
      //inflate your layout
     }
     //reuse convertView

}

Using the above example code, we can check the convertView is null or not. If it is null, that means there is no recycled view. Then we can inflate the layout.

If it is not null, means that not the first time, so we can use convertView and avoid layout inflation.

3. Layout Types

With ListView, you can easily make a list with simple and less code.

Code is a bit complex with RecyclerView, but it provides more options: horizontal, vertical list, grid, and staggered grid

You can also create your custom layout manager using RecyclerView.LayoutManager.

4.Animation Support

In the animation section, RecyclerView is far ahead from ListView. It’s not easy for beginners to make animations in ListView.

But RecyclerView shows Fade in, Fade out, translate and crossfade animations when you add, delete, move and update an item in RecyclerView.

This is default in RecyclerView because it internally uses the DefaultItemAnimator class. That’s why they gave that name.

If you don’t like these animations and want to make your animations make use of RecyclerView.ItemAnimator class.

5. Divider

ListView has divider by default.

The android:divider and android:dividerHeight attributes or setDivider(),setDividerHeight() helps you to make custom divider in ListView.

But RecyclerView doesn’t give these options.

But you can use the DividerItemDecoration class to make a simple divider or Make use of RecyclerView.OnItemDecoration class to decorate the view.

6. Click Events

One of the main disadvantages we face with RecyclerView is that it lacks OnItemClickListener. Because it’s not a subclass of AdapterView like ListView.

It provides RecyclerView.OnItemTouchListener to capture click events. It gives more control to the developer.

You can also use OnClickListener with views on the item.

7.Notify Methods
When notifying adapter, while data change occurs we can call notifyDatasetChanged() with ListView.

But ListView doesn’t know what had happened? It can be the addition, deletion or change of items in the dataset but don’t know what was happened.

For RecyclerView there are lots of notify* methods to inform, including notifyDatasetChanged().

Using the appropriate notify* method can invoke better animation in RecyclerView.

8. Header and Footer
It is easy to add Header and Footer in ListView using addHeaderView() and addFooterView().

But RecyclerView doesn’t have these methods instead it supports different types of view.

Finally, RecyclerView supports Nested Scrolling.

I think that’s enough for the comparison. So use them based on your needs. If you are a beginner in Android App Development, Learn ListView first then go with RecyclerView.

How To Use RecyclerView In Android?

RecyclerView is one of the most valuable widgets in Android development. Out of the box, RecyclerView is lazy. Because it has given responsibilities to different classes.

So before Using RecyclerView, you should know about these classes.

1)RecyclerView.Adapter

This is the most important class in RecyclerView. Same as other AdapterView, It connects the View(RecyclerView) and data.

RecyclerView has no default adapters, So you need to create a custom class by extending Recyclerview.Adapter.

It is responsible for

• Creating ViewHolders
• Binds data to ViewHolders.
• Informs Recyclerview about dataset changes.

Most of the important methods in this class are:
i)OnCreateViewHolder() : This method is called when RecyclerView needed to create a viewholder.
ii)OnBindViewHolder(): Calls whenever needed to bind data with view in viewholder.
iii)getItemCount() : Used to return total number of items in the dataset (ArrayList, array etc).
iv)getItemViewType(): it returns the viewtype based on the position.

2) RecyclerView.LayoutManager

As the name says, it helps RecyclerView to manage layout by positioning each item.

Unlike ListView, RecyclerView shows child items in Horizontal, Vertical list, grid, and staggered grid because of LayoutManager.

Scrolling responsibility is also own by LayoutManager. When you scroll up in RecyclerView, LayoutManager moves your items up.

It provides different classes for arranging items:

i)LinearLayoutManager: Creates vertical and horizontal lists.
ii)GridLayoutManager: Creates grid layouts.
iii)StaggeredGridLayoutManager: Creates StaggeredGrid layouts.
iv)WearableLinearLayoutManager: This class is for wearable devices.

3) RecyclerView.ItemDecoration

The name implies, it decorates RecyclerView’s item or view. It provides not only a divider, Using this abstract class you can draw four sides of the item. When using the divider as a view in XML, it decreases performance. That’s where the importance of this class comes through.

Version 25.1.0 Support library introduces the DividerItemDecoration class, to make a simple divider. Use addItemDecoration() method to add with RecyclerView. This class supports both horizontal and vertical orientations, so you can use it with any of your lists without any worries.

4) RecyclerView.ItemAnimator

Google developers gave more importance to animations in RecyclerView, So RecyclerView provides RecyclerView.ItemAnimator class for handling animations.

You can make custom animations using this class.

Just I said in ListView vs RecyclerView comparison, RecyclerView animates items when item adds, delete or any other move event happens because it internally uses DefaultItemAnimator.

But you can not see these animations when RecyclerView loading for the first time.

5) RecyclerView.ViewHolder

You can consider ViewHolder as something which holds View.

Unlike ListView, we need to make custom ViewHolder class by extending RecyclerView.ViewHolder class.

In this subclass, we must store the item view’s references. This ViewHolder class contains additional information like its position in the layout.

Simple RecyclerView Example With CardView In Android Studio – OnClickListener Included

In this example, I will explain how to create RecyclerView in Android Studio in 10 simple steps with a detailed explanation. The final output will look like below.

I assume that you have created a Project in Android Studio, then add these

STEP 1 – Add Dependencies In build.gradle

RecyclerView and CardView are support libraries, so you must add dependencies in your build.gradle file, If your app needs to support above API 28.0.0, you must use AndroidX libraries. otherwise, you can continue with the support library.

 
/* androidx library*/

    implementation 'androidx.recyclerview:recyclerview:1.1.0'
    implementation 'androidx.cardview:cardview:1.0.0'

/*
support library
 
    implementation 'com.android.support:cardview-v7:28.0.0'
    implementation 'com.android.support:recyclerview-v7:28.0.0'
*/

STEP 2 – Import RecyclerView In Android Studio

Just like ListView, just add it to your layout. here activity_main.xml

This code creates a RecyclerView widget with id “recyclerview”.

• android:scrollbars=”vertical” – It creates vertical scrollbar to the RecyclerView. Otherwise user never get to know how long the RecyclerView is.
• Use android.support.v7.widget.RecyclerView as root widget if you are using the support library, attributes are same as above.

STEP 3 – Create Row Layout For RecyclerView

In this step, we will create a layout and RecyclerView will show it as child items. Right-click on the layout folder in res directory. New->Layout Resource File-> put file name as row_layout.xml and put below code.

• This code creates TextView inside CardView. You can use app: namespace to specify support library attributes.
• if you are using support library, Use android.support.v7.widget.CardView.

STEP 4 – Create An Array And Pass It To RecyclerView Adapter

RecyclerView adapter needs data and layout. So here, we will create an array of months and pass it to the adapter class, which you are going to make in the next step.

class MainActivity : AppCompatActivity()
{

    var months_array = arrayOf("JANUARY","FEBRUARY","MARCH","APRIL","MAY","JUNE","JULY","AUGUST","SEPTEMBER","OCTOBER","NOVEMBER","DECEMBER")

    lateinit var adapter :RecyclerViewAdapter

    override fun onCreate(savedInstanceState: Bundle?)
    {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        adapter = RecyclerViewAdapter(months_array)
        
    }
}

public class MainActivity extends AppCompatActivity
{
    String months_array[] =  {"JANUARY","FEBRUARY","MARCH","APRIL","MAY","JUNE","JULY","AUGUST","SEPTEMBER","OCTOBER","NOVEMBER","DECEMBER"};

    private RecyclerView recyclerview;

    private RecyclerViewAdapter adapter;

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

        recyclerview = (RecyclerView)findViewById(R.id.recyclerview);

        adapter = new RecyclerViewAdapter(months_array);
     }
}

• Creates an array of months
• lateinit: It is used to create properties that can not initialized at first. It says to the compiler that, it will initialize later.
• Creates adapter reference and passed the array to adapter class that you haven’t create. Don’t worry, if it shows in red color

STEP 5 – Create RecyclerViewAdapter Class

We are going to create RecyclerViewAdapter class which extends RecyclerView.Adapter.

Right-click on Java->New->Kotlin File/Class-> Put the class name as RecyclerViewAdapter and make it the same as the below code.

class RecyclerViewAdapter(var months_array: Array)
{

}

public class RecyclerViewAdapter extends RecyclerView.Adapter
{

String[] months_array;

    public RecyclerViewAdapter(String[] months_array)
    {
        this.months_array = months_array;
    }

}

STEP 6 – Create A Custom ViewHolder Class And Extend Adapter Class With RecyclerView.Adapter

In this step, You will create an inner ViewHolder class by extending RecyclerView.ViewHolder. After initializing views in ViewHolder, makes RecyclerViewAdapter extends RecyclerView.Adapter with ViewHolder as the generic parameter. Just like below

class RecyclerViewAdapter(var months_array: Array) : RecyclerView.Adapter()
{

    inner class ViewHolder(itemView : View) : RecyclerView.ViewHolder(itemView)
  {
      var textview = itemView.textview
  }
}

public class RecyclerViewAdapter extends RecyclerView.Adapter
{
    String[] months_array;

    public RecyclerViewAdapter(String[] months_array)
    {
        months_array = months_array;
    }

    class ViewHolder extends RecyclerView.ViewHolder
    {
        TextView textview;

        public ViewHolder(@NonNull  View itemView)
        {
            super(itemView);

            textview=(TextView)itemView.findViewById(R.id.textview);

        }
    }

}

• Creates Inner class ViewHolder which extends RecyclerView.ViewHolder
• Inside viewholder class, initialize row_layout elements. here, TextView.
• If there is red wavy underline below the RecyclerViewAdapter, then click ALT + ENTER. select implement members
• select onCreateViewHolder(),onBindViewHolder() and getItemCount() and click OK

class RecyclerViewAdapter(var months_array: Array) : RecyclerView.Adapter()
{
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder 
    {  }

    override fun getItemCount(): Int 
    {   }

    override fun onBindViewHolder(holder: ViewHolder, p1: Int) 
     { }

    inner class ViewHolder(itemView : View) : RecyclerView.ViewHolder(itemView)
  {
      var textview = itemView.textview
  }
}

public class RecyclerViewAdapter extends RecyclerView.Adapter
{
    String[] months_array;

    public RecyclerViewAdapter(String[] months_array)
    {
        months_array = months_array;
    }

    class ViewHolder extends RecyclerView.ViewHolder
    {
        TextView textview;

        public ViewHolder(@NonNull  View itemView)
        {
            super(itemView);

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

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType) 
    {
        return null;
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder viewHolder, int position) 
    {
    }

    @Override
    public int getItemCount() 
    {
        return 0;
    }

STEP 7 – Specify Total Items Using getItemCount() Method

In this step, we will return the array size in getItemCount() method.

    override fun getItemCount(): Int 
    { 
     return months_array.size
    }

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

• months_array.length returns 12, JAN to DEC.
  

  STEP 8 – Create ViewHolder Using onCreateViewHolder() method

  In this step, I will do two important things.
  1. Layout Inflation
  2. Pass it to ViewHolder.

  This is called whenever RecyclerView needs a ViewHolder.

  override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder
      {
          val inflater = LayoutInflater.from(parent.context)
          val view = inflater.inflate(R.layout.row_layout,parent,false)
          return ViewHolder(view)
      }
  
  

  Click here to view Java code

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

  • parent: RecyclerView, viewType: 0, You can have different types of view. Here is only one viewtype, contain value zero.
  • Creates inflater object using context
  • row_layout inflated and become view object
  • Return ViewHolder with view for reference storage purpose

  STEP 9 – Bind ViewHolder With Data In onBindViewHolder()

  Here we will bind our TextView with array item. Access TextView using viewholder. This method calls when the item wants to show, so here we attach data with the view in ViewHolder.

  
  override fun onBindViewHolder(holder: ViewHolder, position: Int)
      {
          holder.textview.text = months_array[position]
      }
  
  
  

  Click here to view Java code

  
      @Override
      public void onBindViewHolder(@NonNull ViewHolder holder, int position)
      {
          holder.textview.setText(months_array[position]);
      }
  
  

  • You can access each element that initialized in ViewHolder class.
  • Here we access textview and set month from string array

  STEP 10 – Set LayoutManager and Adapter

  In this step, You will set LayoutManager and divider, at last, you will attach an adapter too.
  Let’s back to MainActivity. Put the below code in onCreate() and Run.

  
          //sets layoutmanager
          val layoutManager = LinearLayoutManager(this)
          recyclerview.layoutManager = layoutManager
          //sets divider in the list
          val dividerItemDecoration = DividerItemDecoration(this, LinearLayoutManager.VERTICAL)
          recyclerview.addItemDecoration(dividerItemDecoration)
          //Attaches adapter with RecyclerView.
          recyclerview.adapter = adapter
  
  

  Click here to view Java code

  
          LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
          recyclerview.setLayoutManager(linearLayoutManager);
  
          DividerItemDecoration dividerItemDecoration  = new DividerItemDecoration(this,LinearLayoutManager.VERTICAL);
          recyclerview.addItemDecoration(dividerItemDecoration);
  
          recyclerview.setAdapter(adapter);
  
  

  • • Unlike ListView, We need to implement LayoutManager for RecyclerView. Here we need a Vertical list. Use
    • Make sure you have attached LayoutManger and adapter is not empty, otherwise that may leads to error message
      “e recyclerview no adapter attached skipping layout”

  So use above code and Run

  RecyclerView is ready now.

  STEP 11 – Attach An OnClickListener with Root Element Inside ViewHolder Class

  In this step, you will learn how to get click events and react based on that. Here you will attach OnClickListener with itemView.

              inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView)
              {
               var textview = itemView.textview
  
                 init 
                 {
                 itemView.setOnClickListener {
                   Toast.makeText(itemView.context, months_array[adapterPosition],Toast.LENGTH_SHORT).show()
                        }
                 }
  
               }
          
  

  Click here to view Java code

  class ViewHolder extends RecyclerView.ViewHolder
      {
          TextView textview;
  
          public ViewHolder(@NonNull  View itemView)
          {
              super(itemView);
  
              textview=(TextView)itemView.findViewById(R.id.textview);
  
              itemView.setOnClickListener(new View.OnClickListener()
              {
                  @Override
                  public void onClick(View view)
                  {
                      //getAdapterPosition() method returns clicked item position.  
                      Toast.makeText(view.getContext(), months_array[getAdapterPosition()], Toast.LENGTH_SHORT).show();
                  }
              });
          }
      }
  

  • init block is called after the constructor
  • Using lambda, Create OnClickListener
  • When item clicks, a toast will appear with Month.
  • getAdapterPosition() method returns the clicked item position, Using Kotlin synthetic property we can use “adapterPositon”here.

  Run again.
  Finally, you have made a simple RecyclerView. Congrats!

  How above RecyclerView Adapter Works?

  

  Okay. let’s clear it out… How RecyclerView adapter works based on the above example?

  • At first, getItemCount() method gets called and that will return 12.
  • After that, for creating ViewHolder, onCreateViewHolder() gets called. It inflates the XML layout and makes View and passes it to ViewHolder for storing references.
  • After that onBindViewHolder() gets called, here we use ViewHolder to access the TextView and attaches text. The 0th row is created.
  • The above process repeats and creates as many ViewHolders to fill the screen and even more. It depends on the screen size and layout size.
  • After that RecyclerView stops calling onCreateViewHolder but onBindViewHolder still repeats its job.

  RecyclerView With CheckBox Example In Android Studio

  

  In this example, we will create an app that holds CheckBox and its state. While scrolling too.

  Let’s create a project.
  
  Open your Android Studio.

  Step 1

  Start a new Android Studio project.

  Application Name: RecyclerView With CheckBox In Android Example
  Company Domain: androidride.com

  Check Include Kotlin Support.

  ---

  Step 2

  Select form factors and minimum SDK

  Select API 15: IceCreamSandwich and Click Next.

  ---

  Step 3

  Add Empty activity to Project.

  ---

  After creating the project

  build.gradle(Module.app)

  Add the below code to the dependencies section.

  
  
  //androidx library users
  
      implementation 'androidx.cardview:cardview:1.0.0'
      implementation 'androidx.recyclerview:recyclerview:1.1.0'
  
  /*
  *If you are using the support library
      *implementation 'com.android.support:recyclerview-v7:28.0.0'
      * implementation 'com.android.support:cardview-v7:28.0.0'
      * 
      * */
  
  

  • For Kotlin users, Make sure that you have using kotlin-android-extensions

  activity_main.xml

  • It creates a RecyclerView with Vertical scrollbars and assigns id “recyclerview”.
  • If you are using the support library, replace androidx.recyclerview.widget.RecyclerView with android.support.v7.widget.RecyclerView.

  checkbox_row.xml

  • Creates a CheckBox inside a CardView.
  • Support library users – replace androidx.cardview.widget.CardView with android.support.v7.widget.CardView.

  Data.kt

  
  package com.androidride.recyclerviewwithcheckboxinandroidexample
  
  data class Data(var position: Int)
  
  

  • Only one property : position – We can pass it through constructor
  click here for Java code

  
  
  package com.androidride.recyclerviewwithcheckboxinandroidexample;
  
  public class Data
  {
      int position;
  
      public int getPosition()
      {
          return position;
      }
  
      public void setPosition(int position)
      {
          this.position = position;
      }
  }
  
  
  

  MainActivity.kt

  
  
  class MainActivity : AppCompatActivity()
  {
  
      var list = ArrayList()
  
      lateinit var  adapter : RecyclerViewAdapter
  
      override fun onCreate(savedInstanceState: Bundle?)
      {
          super.onCreate(savedInstanceState)
          setContentView(R.layout.activity_main)
  
          setupdata()
  
          adapter = RecyclerViewAdapter(list)
          //sets layoutmanager
          recyclerview.layoutManager = LinearLayoutManager(this)
          //sets adapter
          recyclerview.adapter = adapter
  
      }
  
      private fun setupdata()
      {
          for(i in 1..30)
          {//creates data object and add it to list.
              var data = Data(i)
  
              list.add(data)
          }
      }
  }
  
  
  

  Click here for java code

  
  
  public class MainActivity extends AppCompatActivity
  {
      ArrayList dataList = new ArrayList<>();
  
      RecyclerView recyclerview;
  
      @Override
      protected void onCreate(Bundle savedInstanceState)
      {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
  
          setupdata();
  
          recyclerview = (RecyclerView)findViewById(R.id.recyclerview);
          //pass list to adapter
          RecyclerViewAdapter adapter = new RecyclerViewAdapter(dataList);
          //sets LinearLayoutManager
          recyclerview.setLayoutManager(new LinearLayoutManager(this));
          //attach adapter with RecyclerView
          recyclerview.setAdapter(adapter);
  
      }
  
      private void setupdata()
      {
          for(int i=1;i<=30;i++)
          {
              //creates a Data object and add the position to it.
              Data data = new Data();
              data.setPosition(i);
              dataList.add(data);
          }
      }
  }
  

  RecyclerViewAdapter.kt

  
  
  class RecyclerViewAdapter(var list: ArrayList) : RecyclerView.Adapter()
  {
  
      var checkBoxStateArray = SparseBooleanArray()
  
      override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder
      {
          val context = parent.context
  //creates inflater
          val inflater = LayoutInflater.from(context)
  //inflates checkbox_row
          val view = inflater.inflate(R.layout.checkbox_row,parent,false)
  //returns ViewHolder with view.
          return ViewHolder(view)
      }
  //returns no of elements, 30
      override fun getItemCount(): Int = list.size
  
      override fun onBindViewHolder(holder: ViewHolder, position: Int)
      {
  
          if(!checkBoxStateArray.get(position,false))
          {//checkbox unchecked.
              holder.checkbox.isChecked = false
          }
          else
          {//checkbox checked
              holder.checkbox.isChecked = true
          }
  //gets position from data object
          var data_position = list.get(position).position
  //sets text with checkbox
          holder.checkbox.text = "CheckBox $data_position"
  
      }
  
      inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView)
      {//Using Kotlin Android Extensions, access checkbox
          var checkbox = itemView.checkbox
  
          init
          {//called after the constructor.
  
              checkbox.setOnClickListener {
  
              if(!checkBoxStateArray.get(adapterPosition,false))
              {//checkbox checked
                  checkbox.isChecked = true
               //stores checkbox states and position
                  checkBoxStateArray.put(adapterPosition,true)
              }
              else
              {//checkbox unchecked
                  checkbox.isChecked = false
  //stores checkbox states and position.
                  checkBoxStateArray.put(adapterPosition,false)
              }
  
              }
          }
  
  
      }
  }
  

  Click here for Java code

  
  
  class RecyclerViewAdapter extends RecyclerView.Adapter
  {
      ArrayList dataList = new ArrayList<>();
  
      SparseBooleanArray checkBoxStateArray = new SparseBooleanArray();
  
      RecyclerViewAdapter(ArrayList dataList)
      {//initializes datalist
          this.dataList = dataList;
      }
  
      @NonNull
      @Override
      public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
          //checkbox_row inflated to view
          View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.checkbox_row,parent,false);
          //returns ViewHolder with view
          return new ViewHolder(view);
      }
  
      @Override
      public void onBindViewHolder(@NonNull ViewHolder holder, int position)
      {
          if(!checkBoxStateArray.get(position,false))
          {
              //checkbox unchecked
              holder.checkBox.setChecked(false);
          }
          else
          {
              //checkbox checked.
              holder.checkBox.setChecked(true);
          }
          //sets checkbox text
          holder.checkBox.setText("CheckBox " + String.valueOf(dataList.get(position).getPosition()));
      }
  
      @Override
      public int getItemCount()
      {//returns no of elements
          return dataList.size();
      }
  
      class ViewHolder extends  RecyclerView.ViewHolder
      {
          CheckBox checkBox;
          public ViewHolder(@NonNull View itemView)
          {
              super(itemView);
              checkBox = (CheckBox)itemView.findViewById(R.id.checkbox);
  
              checkBox.setOnClickListener(new View.OnClickListener()
              {
                  @Override
                  public void onClick(View view)
                  {
                      //getAdapterPosition returns clicked item position
                      int position = getAdapterPosition();
                      if(!checkBoxStateArray.get(position,false))
                      {
                          //checkbox checked
                          checkBox.setChecked(true);
                          //checkbox state stored.
                          checkBoxStateArray.put(position,true);
                      }
                      else
                      {
                          //checkbox unchecked.
                          checkBox.setChecked(false);
                          //checkbox state stored
                          checkBoxStateArray.put(position,false);
                      }
                  }
              });
          }
  
      }
  }
  

  • Using Kotlin synthetic properties, we can use adapterPosition for getAdapterPosition()
  • Using SparseBooleanArray, we stores position and boolean value

  Now run the project.

  

  oh, that’s a long tutorial.

  Finally, We are here.

  Guys, Shares really encourage me to create more rich content. Please share this post with your colleagues, family, and friends.