Radio Button in Kotlin

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    tools:context=".MainActivity"
    android:orientation="vertical">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Radio Button Example"
        android:textAllCaps="true"
        android:textStyle="italic"
        android:textSize="20sp"
        android:textColor="#309"
        android:padding="5dp"
        android:layout_margin="5dp"
        android:id="@+id/tv1"/>

    <RadioGroup
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/rg"
        android:orientation="horizontal">

    <RadioButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/r1"
        android:text="Male"
        android:textAllCaps="true"
        android:textStyle="italic"
        android:textSize="20sp"
        android:textColor="#309"
        android:padding="5dp"
        android:layout_margin="5dp"></RadioButton>

    <RadioButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/r2"
        android:text="Female"
        android:textAllCaps="true"
        android:textStyle="italic"
        android:textSize="20sp"
        android:textColor="#309"
        android:padding="5dp"
        android:layout_margin="5dp"></RadioButton>

    </RadioGroup> 


</LinearLayout>

MainActivity.kt

package com.androinidan.radiobutton

import android.annotation.SuppressLint
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.ImageButton
import android.widget.ImageView
import android.widget.RadioGroup
import android.widget.RatingBar
import android.widget.TextView
import android.widget.Toast

class MainActivity : AppCompatActivity() {

    var radiogroup: RadioGroup?=null
    var tv: TextView?=null
    
    @SuppressLint("WrongConstant")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        radiogroup=findViewById(R.id.rg)
        tv=findViewById(R.id.tv1)
        
        radiogroup!!.setOnCheckedChangeListener{group, checkedId->

            if(checkedId==R.id.r1) {

                tv!!.text = ("Male")
                Toast.makeText(applicationContext, "You selected Male", Toast.LENGTH_LONG).show()
            }
            else {
                tv!!.text = ("Female")
                Toast.makeText(applicationContext, "You selected female", Toast.LENGTH_SHORT).show()
            }

        }

       
        
    }
}