Android Webview communication between native and javascript

index.html

 <input type="button" value="Say hello" onClick="showAndroidToast('Hello Android!')" />

    <script type="text/javascript">
        function showAndroidToast(toast) {
            Android.showToast(toast);
        }
 </script>

MainActivity.kt

package com.example.greetingcard

import android.annotation.SuppressLint
import android.os.Bundle
import android.view.ViewGroup
import android.webkit.WebView
import android.webkit.WebViewClient
import android.webkit.JavascriptInterface
import android.content.Context
import android.widget.Toast
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.material.*
import androidx.compose.runtime.Composable
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.viewinterop.AndroidView
import com.example.greetingcard.ui.theme.GreetingCardTheme

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            GreetingCardTheme {
                MainContent()
            }
        }
    }
}


@Composable
fun MainContent() {
    Scaffold(
        topBar = { TopAppBar(title = { Text("GFG | WebView", color = Color.White) }, backgroundColor = Color(0xff0f9d58)) },
        content = { MyContent() }
    )
}

class WebAppInterface(private val mContext: Context) {
    /** Show a toast from the web page  */
    @JavascriptInterface
    fun showToast(toast: String) {
        Toast.makeText(mContext, toast, Toast.LENGTH_SHORT).show()
    }
}

@SuppressLint("SetJavaScriptEnabled")
@Composable
fun MyContent(){

    // Declare a string that contains a url
    val mUrl = "http://10.71.56.41:8000/"

    // Adding a WebView inside AndroidView
    // with layout as full screen
    AndroidView(factory = {
        WebView(it).apply {
            layoutParams = ViewGroup.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT,
                ViewGroup.LayoutParams.MATCH_PARENT
            )
            webViewClient = WebViewClient()
            settings.javaScriptEnabled = true
            addJavascriptInterface(WebAppInterface(context), "Android")
            loadUrl(mUrl)
        }
    }, update = {
        it.loadUrl(mUrl)
    })
}

// For displaying preview in
// the Android Studio IDE emulator
@Preview(showBackground = true)
@Composable
fun DefaultPreview() {
    MainContent()
}