SearchView in Android with RecyclerView

public class CourseModel {
    // variables for our course
    // name and description.
    private String courseName;
    private String courseDescription;

    // creating constructor for our variables.
    public CourseModel(String courseName, String courseDescription) {
        this.courseName = courseName;
        this.courseDescription = courseDescription;
    }

    // creating getter and setter methods.
    public String getCourseName() {
        return courseName;
    }

    public void setCourseName(String courseName) {
        this.courseName = courseName;
    }

    public String getCourseDescription() {
        return courseDescription;
    }

    public void setCourseDescription(String courseDescription) {
        this.courseDescription = courseDescription;
    }
}

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

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

    // creating a variable for array list and context.
    private ArrayList<CourseModel> courseModelArrayList;

    // creating a constructor for our variables.
    public CourseAdapter(ArrayList<CourseModel> courseModelArrayList, Context context) {
        this.courseModelArrayList = courseModelArrayList;
    }

    // method for filtering our recyclerview items.
    public void filterList(ArrayList<CourseModel> filterlist) {
        // below line is to add our filtered
        // list in our course array list.
        courseModelArrayList = filterlist;
        // below line is to notify our adapter 
        // as change in recycler view data.
        notifyDataSetChanged();
    }
    
    @NonNull
    @Override
    public CourseAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        // below line is to inflate our layout.
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.course_rv_item, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull CourseAdapter.ViewHolder holder, int position) {
        // setting data to our views of recycler view.
        CourseModel model = courseModelArrayList.get(position);
        holder.courseNameTV.setText(model.getCourseName());
        holder.courseDescTV.setText(model.getCourseDescription());
    }

    @Override
    public int getItemCount() {
        // returning the size of array list.
        return courseModelArrayList.size();
    }

    public static class ViewHolder extends RecyclerView.ViewHolder {
        // creating variables for our views.
        private final TextView courseNameTV;
        private final TextView courseDescTV;
        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            // initializing our views with their ids.
            courseNameTV = itemView.findViewById(R.id.idTVCourseName);
            courseDescTV = itemView.findViewById(R.id.idTVCourseDescription);
        }
    }
}

package com.geeksforgeeks.searchview_android;

import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.appcompat.widget.SearchView;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    // creating variables for UI components
    private RecyclerView courseRV;
    private Toolbar toolbar;

    // variable for our adapter class and array list
    private CourseAdapter adapter;
    private ArrayList<CourseModel> courseModelArrayList;

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

        // initializing variables
        courseRV = findViewById(R.id.idRVCourses);
        toolbar = findViewById(R.id.toolbar);

        // setting the toolbar as the ActionBar
        setSupportActionBar(toolbar);

        // calling method to build recycler view
        buildRecyclerView();
    }

    // calling onCreateOptionsMenu to inflate our menu file
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // get the MenuInflater
        MenuInflater inflater = getMenuInflater();

        // inflate the menu
        inflater.inflate(R.menu.search, menu);

        // get the search menu item
        MenuItem searchItem = menu.findItem(R.id.actionSearch);

        // get the SearchView from the menu item
        SearchView searchView = (SearchView) searchItem.getActionView();

        // set the on query text listener for the SearchView
        searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextSubmit(String query) {
                return false;
            }

            @Override
            public boolean onQueryTextChange(String newText) {
                // call a method to filter your RecyclerView
                filter(newText);
                return false;
            }
        });
        return true;
    }

    // method to filter data based on query
    private void filter(String text) {
        // creating a new array list to filter data
        ArrayList<CourseModel> filteredlist = new ArrayList<>();

        // running a for loop to compare elements
        for (CourseModel item : courseModelArrayList) {
            // checking if the entered string matches any item of our recycler view
            if (item.getCourseName().toLowerCase().contains(text.toLowerCase())) {
                // adding matched item to the filtered list
                filteredlist.add(item);
            }
        }

        if (filteredlist.isEmpty()) {
            // displaying a toast message if no data found
            Toast.makeText(this, "No Data Found..", Toast.LENGTH_SHORT).show();
        } else {
            // passing the filtered list to the adapter class
            adapter.filterList(filteredlist);
        }
    }

    // method to build RecyclerView
    private void buildRecyclerView() {
        // creating a new array list
        courseModelArrayList = new ArrayList<>();

        // adding data to the array list
        courseModelArrayList.add(new CourseModel("DSA", "DSA Self Paced Course"));
        courseModelArrayList.add(new CourseModel("JAVA", "JAVA Self Paced Course"));
        courseModelArrayList.add(new CourseModel("C++", "C++ Self Paced Course"));
        courseModelArrayList.add(new CourseModel("Python", "Python Self Paced Course"));
        courseModelArrayList.add(new CourseModel("Fork CPP", "Fork CPP Self Paced Course"));

        // initializing the adapter class
        adapter = new CourseAdapter(courseModelArrayList, MainActivity.this);

        // adding layout manager to the RecyclerView
        LinearLayoutManager manager = new LinearLayoutManager(this);
        courseRV.setHasFixedSize(true);

        // setting layout manager to the RecyclerView
        courseRV.setLayoutManager(manager);

        // setting adapter to the RecyclerView
        courseRV.setAdapter(adapter);
    }
}