Android RecyclerView in Kotlin

July 23, 2024 by
365Bloggy

In this post, you'll learn how to use Kotlin to implement RecyclerView on Android. Before we go any further, tell us about RecyclerView. A RecyclerView is a more advanced version of the ListView that has better performance. When you have a large number of objects to display, you can utilise RecyclerView. It can reuse its views.

In this article, you will learn how to create your RecyclerView Example of RecyclerView​ in Android. So let’s take example of RecyclerView  activity codes  in Android of Mobile application.  

 Example of RecyclerView 

                                                   

Step-by-Step Im​plementation

​Step 1: Create a New Project in Android ​studio (File >new  project).  


Step 2: Create an activity_main.xml file in your layout folder . path (res>layout)

Implement the same in​voke the following code inside activity_main.xml file.

 <?xml version="1.0" encoding="utf-8"?>
 <androidx.constraintlayout.widget.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="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity"
    tools:ignore="HardcodedText">
    <androidx.appcompat.widget.AppCompatButton
   
    <androidx.recyclerview.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scrollbars="vertical"
        android:id="@+id/recyclerView"
        tools:context="example.javatpoint.com.recyclerviewlist.MainActivity"/>
    
 </androidx.constraintlayout.widget.ConstraintLayout>
Step 3: Create an customAdapter.kt file in your package folder .

Implement the same invoke the fol​low​ing code inside customAdapter.kt file.

 import android.annotation.SuppressLint
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import android.widget.ImageView
 import android.widget.TextView
 import androidx.recyclerview.widget.RecyclerView

 class CustomAdapter(private val mList: List<ItemsViewModel>) :
    RecyclerView.Adapter<CustomAdapter.ViewHolder>() {
    private var lastCheckedPosition = -1
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val view = LayoutInflater.from(parent.context)
            .inflate(R.layout.list_item, parent, false)
        return ViewHolder(view)
    }

    override fun onBindViewHolder(holder: ViewHolder, @SuppressLint("RecyclerView") position: Int) {
        holder.imageView.setImageResource(ItemsViewModel.image)
        holder.textView.text = ItemsViewModel.text
    }
    
    override fun getItemCount(): Int {
        return mList.size
    }

    class ViewHolder(ItemView: View) : RecyclerView.ViewHolder(ItemView) {
        val imageView: ImageView = itemView.findViewById(R.id.imgflag)
        val textView: TextView = itemView.findViewById(R.id.txtTitle)
        val imgeenglish: ImageView = itemView.findViewById(R.id.imgeenglish)
    }
 }
Step 4: Create an ItemsViewModel.kt file in your package folder .

Implement the same invoke the fol​low​ing code inside ItemsViewModel.kt file.

 data class ItemsViewModel(val image: Int, val text: String, var ischeck:Boolean)
Step 5: Create an MainActivity.kt file in your package folder .

Implement the same invoke the fol​low​ing code inside MainActivity.kt file.

 import android.annotation.SuppressLint
 import android.os.Bundle
 import android.view.View
 import androidx.appcompat.app.AppCompatActivity
 import androidx.appcompat.widget.AppCompatButton
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView

 class MainActivity : AppCompatActivity() {
    @SuppressLint("MissingInflatedId")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val btnopen = findViewById<View>(R.id.btnopen) as AppCompatButton
        btnopen.setOnClickListener {

        }
        val recyclerview = findViewById<RecyclerView>(R.id.recyclerView)
        recyclerview.layoutManager = LinearLayoutManager(this)
        val data = ArrayList<ItemsViewModel>()
        for (i in 1..20) {
            data.add(ItemsViewModel(R.drawable.next, "Item $i", false))
        }
        val adapter = CustomAdapter(data)
        recyclerview.adapter = adapter
     }

 }

Step 6 : Output of above example.

                                                         

Happy coding!

365Bloggy July 23, 2024
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