Android RecyclerView in Kotlin

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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