Easy Android RecyclerView implementation with Adapter, Holder, Click Listener Example in Java and Kotlin both

With lot of efforts and writing huge code for Android RecyclerView, I ended up with this code, but for now I think it is very easy to use and handle click listener. This implementation is different from any other implementation you see on many sites.

Let's begin with coding...

Create a new project with Android Studio with empty Activity "MainActivity"

First we need to create a model (create separate package for all models is good)

models/Student.java

package com.masoomyf.recyclerviewexample.models;

public class Student {
    private int id;
    private int age;

    private String name;

    public Student(int id, int age, String name) {
        this.id = id;
        this.age = age;
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

KOTLIN
models/Student.kt

package com.masoomyf.recyclerviewexample.models;

class Student(var id: Int, var age: Int, var name: String?)

Add RecyclerView to your main_layout.xml, it will auto configure RecyclerView library for you in gradle. (Add RecyclerView in Design Tab only)

Now create layout xml file: row_layout_student.xml 

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
                                             xmlns:app="http://schemas.android.com/apk/res-auto"
                                             xmlns:tools="http://schemas.android.com/tools"
                                             android:layout_width="match_parent"
                                             android:layout_height="wrap_content">

    <TextView
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:id="@+id/tvStudentName" app:layout_constraintStart_toStartOf="parent"
            android:layout_marginStart="8dp"
            android:layout_marginTop="8dp" app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintEnd_toEndOf="parent" android:layout_marginEnd="8dp" tools:text="Student Name"
            android:textStyle="bold"/>
    <TextView
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:id="@+id/tvStudentId" app:layout_constraintStart_toStartOf="parent" android:layout_marginStart="8dp"
            android:layout_marginTop="8dp" app:layout_constraintTop_toBottomOf="@+id/tvStudentName"
            tools:text="ID: 12345"
            app:layout_constraintHorizontal_bias="0.5" app:layout_constraintEnd_toStartOf="@+id/tvStudentAge"/>
    <TextView
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:id="@+id/tvStudentAge" app:layout_constraintEnd_toEndOf="parent" android:layout_marginEnd="8dp"
            android:layout_marginTop="8dp" app:layout_constraintTop_toBottomOf="@+id/tvStudentName"
            app:layout_constraintStart_toEndOf="@+id/tvStudentId" app:layout_constraintHorizontal_bias="0.5"
            tools:text="Age: 21"/>
    <View
            android:id="@+id/divider"
            android:layout_width="0dp"
            android:layout_height="1dp"
            android:background="?android:attr/listDivider"
            app:layout_constraintEnd_toEndOf="parent"
            android:layout_marginEnd="8dp" app:layout_constraintStart_toStartOf="parent"
            android:layout_marginStart="8dp" app:layout_constraintTop_toBottomOf="@+id/tvStudentAge"/>
</android.support.constraint.ConstraintLayout>

Now create Adapter for RecyclerView: 

package com.masoomyf.recyclerviewexample.adapters;

import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import com.masoomyf.recyclerviewexample.R;
import com.masoomyf.recyclerviewexample.models.Student;

import java.util.List;

public class StudentAdapter extends RecyclerView.Adapter<StudentAdapter.StudentHolder> {
    //We don't need any context field. We can get context from viewGroup.
    private List<Student> studentList;
    private View.OnClickListener clickListener;

    public StudentAdapter(List<Student> studentList) {
        this.studentList = studentList;
    }


    @NonNull
    @Override
    public StudentHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        View view = LayoutInflater.from(viewGroup.getContext())
                .inflate(R.layout.row_layout_student,viewGroup,false);

        return new StudentHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull StudentHolder studentHolder, int i) {
        studentHolder.bind(studentList.get(i));
    }

    public void setClickListener(View.OnClickListener clickListener) {
        this.clickListener = clickListener;
    }

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

    class StudentHolder extends RecyclerView.ViewHolder{
        private TextView tvStudentId;
        private TextView tvStudentName;
        private TextView tvStudentAge;

        StudentHolder(@NonNull View itemView) {
            super(itemView);
            //Setup all views inside itemView
            tvStudentId = itemView.findViewById(R.id.tvStudentId);
            tvStudentAge = itemView.findViewById(R.id.tvStudentAge);
            tvStudentName = itemView.findViewById(R.id.tvStudentName);
            //set the itemView click listener.
            itemView.setOnClickListener(clickListener);
        }
        //It's look beautiful and become easy when we create bind method inside holder.
        void bind(Student student){
            tvStudentAge.setText(String.valueOf("Age: " + student.getAge()));
            tvStudentName.setText(student.getName());
            tvStudentId.setText(String.valueOf("Id: "+student.getId()));
            //Always set tag after binding, if there is already a tag in itemView, it get replaced.
            itemView.setTag(student);
        }
    }
}

KOTLIN

import android.support.v7.widget.RecyclerView
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import com.masoomyf.recyclerviewexample.R
import com.masoomyf.recyclerviewexample.models.Student
import kotlinx.android.synthetic.main.row_layout_student.view.*


class StudentAdapter(
    private val studentList: List<Student>
) : RecyclerView.Adapter<StudentAdapter.StudentHolder>() {

    var clickListener: View.OnClickListener? = null

    override fun onCreateViewHolder(viewGroup: ViewGroup, i: Int): StudentHolder {
        val view = LayoutInflater.from(viewGroup.context)
            .inflate(R.layout.row_layout_student, viewGroup, false)

        return StudentHolder(view)
    }

    override fun onBindViewHolder(studentHolder: StudentHolder, i: Int) = studentHolder.bind(studentList[i])


    override fun getItemCount(): Int = studentList.size
   

    inner class StudentHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {

        init {
            itemView.setOnClickListener(clickListener)
        }

        //It's look beautiful and become easy when we create bind method inside holder.
        fun bind(student: Student) {
            with(itemView) {
                tvStudentAge.text = "Age: %d".format(student.age)
                tvStudentName.text = student.name
                tvStudentId.text = "Id: %d".format(student.id)
                //Always set tag after binding, if there is already a tag in itemView, it get replaced.
                tag = student
            }
        }
    }
}

Add code in MainActivity.java to complete RecyclerView

package com.masoomyf.recyclerviewexample;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.Toast;
import com.masoomyf.recyclerviewexample.adapters.StudentAdapter;
import com.masoomyf.recyclerviewexample.models.Student;

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

public class MainActivity extends AppCompatActivity {
    //Recycler view instance holder.
    
    private RecyclerView rvStudent;
    private List<Student> studentList;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setupObject();
        setupUI();
    }
    //It's good to setup all object in seperate method
    private void setupObject() {
        studentList = new ArrayList<>();
    }
    
    //This method will setup the whole UI, it's better to setup UI in seperate method.
    private void setupUI() {
        rvStudent = findViewById(R.id.rvStudent);
        //We don't need to declare adapter variable in field.
        // We can get adapter through recycler view whenever we need.
        StudentAdapter adapter = new StudentAdapter(studentList);
        adapter.setClickListener(studentListClickListener);
        generateDummyData();
        rvStudent.setLayoutManager(new LinearLayoutManager(this));
        rvStudent.setAdapter(adapter);

    }
    //Add some dummy data to list.
    private void generateDummyData() {
        studentList.add(new Student(1,19,"Yash"));
        studentList.add(new Student(2,21,"Masoom"));
        studentList.add(new Student(3,22,"Yashika"));
        studentList.add(new Student(4,24,"Amiy"));
    }
    //A click listener object that will fire when itemView get clicked with current item tag
    private View.OnClickListener studentListClickListener = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            //Get the Student object from itemView tag.
            Student student = (Student) v.getTag();
            Toast.makeText(MainActivity.this,student.getName(), Toast.LENGTH_SHORT).show();
        }
    };
}

KOTLIN

package com.masoomyf.recyclerviewexample

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.support.v7.widget.LinearLayoutManager
import android.view.View
import android.widget.Toast
import com.masoomyf.recyclerviewexample.adapters.StudentAdapter
import com.masoomyf.recyclerviewexample.models.Student
import kotlinx.android.synthetic.main.activity_main.*



class MainActivity : AppCompatActivity() {

    private val studentList = arrayListOf<Student>()

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

    private fun setupUI() {
        val studentAdapter = StudentAdapter(studentList).apply {
            clickListener = studentClickListener
        }

        generateDummyData()

        with(rvStudent){
            layoutManager = LinearLayoutManager(this@MainActivity)
            adapter = studentAdapter
        }
    }

    private fun generateDummyData() {
        with(studentList) {
            add(Student(1, 19, "Yash"))
            add(Student(2, 21, "Masoom"))
            add(Student(3, 22, "Yashika"))
            add(Student(4, 24, "Amiy"))
        }
    }


    private val studentClickListener = View.OnClickListener {
        val student = it.tag as Student
        Toast.makeText(this,"Student Name: ${student.name}",Toast.LENGTH_LONG).show()
    }
}