MainActivity.kt

package com.example.myapplication

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.webkit.WebView
import android.widget.CheckBox
import android.widget.EditText

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val animals_input = findViewById<EditText>(R.id.animals_input)
        val webView: WebView = findViewById(R.id.webview)
        webView.loadUrl("https://github.com")

        val checkbox = findViewById<CheckBox>(R.id.animals)

        checkbox.setOnCheckedChangeListener { _, isChecked ->
            if (isChecked) {
                animals_input.visibility = View.VISIBLE
            } else {
                animals_input.visibility = View.GONE
            }
        }

    }
}