Simple RecyclerView example in Android

RecyclerView makes it easy to efficiently display large sets of data. You supply the data and define how each item looks, and the RecyclerView library dynamically creates the elements when they're needed.

As the name implies, RecyclerView recycles those individual elements. When an item scrolls off the screen, RecyclerView doesn't destroy its view. Instead, RecyclerView reuses the view for new items that have scrolled onscreen. This reuse vastly improves performance, improving your app's responsiveness and reducing power consumption.

Now RecyclerView is part of Android Jetpack

Example:

MainActivity.java

import android.support.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import androidx.fragment.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;

import java.util.ArrayList;
import java.util.List;


public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment())
                    .commit();
        }
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {

        RecyclerViewAdapter adapter;
        RecyclerView recyclerView;
        private static List<Model> demoData;

        public PlaceholderFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            return inflater.inflate(R.layout.fragment_main, container, false);
        }

        @Override
        public void onActivityCreated(@Nullable Bundle savedInstanceState) {
            super.onActivityCreated(savedInstanceState);
            recyclerView = (RecyclerView) getView().findViewById(R.id.myList);
            recyclerView.setHasFixedSize(true);
            LinearLayoutManager llm = new LinearLayoutManager(getActivity());
            llm.setOrientation(LinearLayoutManager.VERTICAL);
            recyclerView.setLayoutManager(llm);

            demoData = new ArrayList<Model>();
            char c = 'A';
            for (byte i = 0; i < 20; i++) {
                Model model = new Model();
                model.name = c++;
                model.age = (byte) (20 + i);
                demoData.add(model);
            }
            adapter = new RecyclerViewAdapter(demoData);
            recyclerView.setAdapter(adapter);
        }
    }
}

RecyclerViewAdapter.java

import androidx.recyclerview.widget.RecyclerView;
import android.util.SparseBooleanArray;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.List;

public class RecyclerViewAdapter
        extends RecyclerView.Adapter
        <RecyclerViewAdapter.ListItemViewHolder> {

    private List<Model> items;
    private SparseBooleanArray selectedItems;

    RecyclerViewAdapter(List<Model> modelData) {
        if (modelData == null) {
            throw new IllegalArgumentException("modelData must not be null");
        }
        items = modelData;
        selectedItems = new SparseBooleanArray();
    }

    @Override
    public ListItemViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
        View itemView = LayoutInflater.
                from(viewGroup.getContext()).
                inflate(R.layout.item_demo_01, viewGroup, false);
        return new ListItemViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(ListItemViewHolder viewHolder, int position) {
        Model model = items.get(position);
        viewHolder.name.setText(String.valueOf(model.name));
        viewHolder.age.setText(String.valueOf(model.age));
        viewHolder.itemView.setActivated(selectedItems.get(position, false));
    }

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

    public final static class ListItemViewHolder extends RecyclerView.ViewHolder {
        TextView name;
        TextView age;

        public ListItemViewHolder(View itemView) {
            super(itemView);
            name = (TextView) itemView.findViewById(R.id.txt_name);
            age = (TextView) itemView.findViewById(R.id.txt_age);
        }
    }
}

And your
fragment_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    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=".MyActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/myList"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</RelativeLayout>

Use following dependancy

implementation 'androidx.recyclerview:recyclerview:1.1.0'

Screen shot of this example

I hope this post is useful. kindly share your feedback as comment here.

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Source code on GitHub

Thank You